Climate control panel overheating
08-30-2007 | 06:45 PM
#1
Guest
Posts: n/a
Climate control panel overheating
I've searched the group and can't find a thread for this particular
problem.
I have a 1991 Cherokee Lorado. Recently, the heater blower switch
heated up and melted the plastic wire loom. The switch got so hot
that the plastic parts inside the switch melted and fused. I also
noticed that one of the connections on the plug that goes to the
heater/ac control panel (NOT the blower switch) also melted (only one
of the six connectors on that plug).
The first thing I suspected was the heater resister. I know that
usually, when the resistor starts to go the blower will only work at
high speed. That never happened in this case. Until the switch
melted, the blower, heater and a/c worked fine. I replaced the switch
and the heater resistor but the panel and the blower switch still get
too hot to touch. The blower seems to work fine on all speeds, the ac
works (it never got super cold but it does cool things off) and so do
the other controls. BTW all fuses seem to be fine.
There seems to be resistance in the system somewhere but I can't
figure out where.
Can anyone tell me how to trouble shoot the system to check for a bad
ground or something? How can I check the blower to see if it is
causing a problem. I can put a VoltMeter on it but I don't know what
readings I should be getting.
Any help or ideas would be great.
Thanks, Jim
problem.
I have a 1991 Cherokee Lorado. Recently, the heater blower switch
heated up and melted the plastic wire loom. The switch got so hot
that the plastic parts inside the switch melted and fused. I also
noticed that one of the connections on the plug that goes to the
heater/ac control panel (NOT the blower switch) also melted (only one
of the six connectors on that plug).
The first thing I suspected was the heater resister. I know that
usually, when the resistor starts to go the blower will only work at
high speed. That never happened in this case. Until the switch
melted, the blower, heater and a/c worked fine. I replaced the switch
and the heater resistor but the panel and the blower switch still get
too hot to touch. The blower seems to work fine on all speeds, the ac
works (it never got super cold but it does cool things off) and so do
the other controls. BTW all fuses seem to be fine.
There seems to be resistance in the system somewhere but I can't
figure out where.
Can anyone tell me how to trouble shoot the system to check for a bad
ground or something? How can I check the blower to see if it is
causing a problem. I can put a VoltMeter on it but I don't know what
readings I should be getting.
Any help or ideas would be great.
Thanks, Jim
08-31-2007 | 12:07 AM
#2
Guest
Posts: n/a
Re: Climate control panel overheating
On Aug 30, 2:45 pm, Jim <jb-ha...@pacbell.net> wrote:
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
08-31-2007 | 12:07 AM
#3
Guest
Posts: n/a
Re: Climate control panel overheating
On Aug 30, 2:45 pm, Jim <jb-ha...@pacbell.net> wrote:
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
08-31-2007 | 12:07 AM
#4
Guest
Posts: n/a
Re: Climate control panel overheating
On Aug 30, 2:45 pm, Jim <jb-ha...@pacbell.net> wrote:
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
08-31-2007 | 12:07 AM
#5
Guest
Posts: n/a
Re: Climate control panel overheating
On Aug 30, 2:45 pm, Jim <jb-ha...@pacbell.net> wrote:
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
> I've searched the group and can't find a thread for this particular
> problem.
> I have a 1991 Cherokee Lorado. Recently, the heater blower switch
> heated up and melted the plastic wire loom. The switch got so hot
> that the plastic parts inside the switch melted and fused. I also
> noticed that one of the connections on the plug that goes to the
> heater/ac control panel (NOT the blower switch) also melted (only one
> of the six connectors on that plug).
> The first thing I suspected was the heater resister. I know that
> usually, when the resistor starts to go the blower will only work at
> high speed. That never happened in this case. Until the switch
> melted, the blower, heater and a/c worked fine. I replaced the switch
> and the heater resistor but the panel and the blower switch still get
> too hot to touch. The blower seems to work fine on all speeds, the ac
> works (it never got super cold but it does cool things off) and so do
> the other controls. BTW all fuses seem to be fine.
> There seems to be resistance in the system somewhere but I can't
> figure out where.
> Can anyone tell me how to trouble shoot the system to check for a bad
> ground or something? How can I check the blower to see if it is
> causing a problem. I can put a VoltMeter on it but I don't know what
> readings I should be getting.
>
> Any help or ideas would be great.
> Thanks, Jim
Well the same thing happened on my 93 Cherokee. I smelled something
and then the fan quit. I took the dash apart and found the melted
mess. I went to the junk yard and found two others melted before I
found a good one. I cut the wires with the switch and installed it in
mine. I gave the Jeep to my sister and 5 years later it is still
fine. Maybe it is a switch and load issue.
09-01-2007 | 12:44 PM
#6
Guest
Posts: n/a
Re: Climate control panel overheating
On Thu, 30 Aug 2007 14:45:58 -0700, Jim <jb-hammo@pacbell.net> wrote:
>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
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>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
---
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 000770-2, 09/01/2007
Tested on: 9/1/2007 11:44:30 AM
avast! - copyright (c) 1988-2007 ALWIL Software.
http://www.avast.com
09-01-2007 | 12:44 PM
#7
Guest
Posts: n/a
Re: Climate control panel overheating
On Thu, 30 Aug 2007 14:45:58 -0700, Jim <jb-hammo@pacbell.net> wrote:
>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
---
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 000770-2, 09/01/2007
Tested on: 9/1/2007 11:44:30 AM
avast! - copyright (c) 1988-2007 ALWIL Software.
http://www.avast.com
>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
---
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 000770-2, 09/01/2007
Tested on: 9/1/2007 11:44:30 AM
avast! - copyright (c) 1988-2007 ALWIL Software.
http://www.avast.com
09-01-2007 | 12:44 PM
#8
Guest
Posts: n/a
Re: Climate control panel overheating
On Thu, 30 Aug 2007 14:45:58 -0700, Jim <jb-hammo@pacbell.net> wrote:
>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
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>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
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Tested on: 9/1/2007 11:44:30 AM
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09-01-2007 | 12:44 PM
#9
Guest
Posts: n/a
Re: Climate control panel overheating
On Thu, 30 Aug 2007 14:45:58 -0700, Jim <jb-hammo@pacbell.net> wrote:
>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
---
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Virus Database (VPS): 000770-2, 09/01/2007
Tested on: 9/1/2007 11:44:30 AM
avast! - copyright (c) 1988-2007 ALWIL Software.
http://www.avast.com
>I've searched the group and can't find a thread for this particular
>problem.
>I have a 1991 Cherokee Lorado. Recently, the heater blower switch
>heated up and melted the plastic wire loom. The switch got so hot
>that the plastic parts inside the switch melted and fused. I also
>noticed that one of the connections on the plug that goes to the
>heater/ac control panel (NOT the blower switch) also melted (only one
>of the six connectors on that plug).
>The first thing I suspected was the heater resister. I know that
>usually, when the resistor starts to go the blower will only work at
>high speed. That never happened in this case. Until the switch
>melted, the blower, heater and a/c worked fine. I replaced the switch
>and the heater resistor but the panel and the blower switch still get
>too hot to touch. The blower seems to work fine on all speeds, the ac
>works (it never got super cold but it does cool things off) and so do
>the other controls. BTW all fuses seem to be fine.
>There seems to be resistance in the system somewhere but I can't
>figure out where.
>Can anyone tell me how to trouble shoot the system to check for a bad
>ground or something? How can I check the blower to see if it is
>causing a problem. I can put a VoltMeter on it but I don't know what
>readings I should be getting.
>
>Any help or ideas would be great.
>Thanks, Jim
Your initial switch failure was probably a combination of two or more
things.
- A blower which is drawing high current, the bushings might be
getting worn out or the blower wheel might be lightly rubbing. This
creates a lot of extra current in the circuit.
- A switch which was getting old with dirty contacts or terminals
Together these probably caused the switch and connector / terminals to
overheat.
You replaced the switch (did you replace the connector and terminals
too?) which fixed part of the problem. Check out the blower and if
it is rubbing lightly or a little slow it should probably be replaced
as well.
Things like bad grounds or corroded terminals add resistance into the
circuit and decrease the current. But they can be the cause of local
overheating if there is high current in the circuit.
reboot
---
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Tested on: 9/1/2007 11:44:30 AM
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09-02-2007 | 02:20 AM
#10
Guest
Posts: n/a
Re: Climate control panel overheating
I do not know about the rest of you? But replacing the blower sounds
like it but be a pain in the neck to do. I know with my 99 wrangler TJ
I have to take the whole dash up and out just to get to the blower
motor. I think you may need to take dash out of yours to get to your
blower motor. But I can be worng very easy. What I would do is replace
the heater/AC control and if it happins again take a look at taking
your rig to the shop But if you got the tools the skills and the time.
Take a look at the heater control box under the dash and see if any of
the motors are running hot or slow. Replace them if they are running
hot or slow. I hope this is of any help. Jamie
like it but be a pain in the neck to do. I know with my 99 wrangler TJ
I have to take the whole dash up and out just to get to the blower
motor. I think you may need to take dash out of yours to get to your
blower motor. But I can be worng very easy. What I would do is replace
the heater/AC control and if it happins again take a look at taking
your rig to the shop But if you got the tools the skills and the time.
Take a look at the heater control box under the dash and see if any of
the motors are running hot or slow. Replace them if they are running
hot or slow. I hope this is of any help. Jamie