JK Heater Controls

J

jdruid

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Joined
Nov 15, 2021
Messages
3
Location
Newtown CT
I know this has been discussed at length in this forum and others but I am at a loss for what else could be causing the heater/ac controls to only work 50% of the time.

What works:
- Blower works
- Speed works
- Vent selection works
- Heat / AC works 50% of the time...meaning it is a crap shoot if it will work when I start the jeep. When it works it is great.
- Heater core is hot

What I replaced:
- Coolant flushed
- Blend door on drivers side
- HVAC control unit
- disconnected battery each time

Is there something else? No matter when I start the Jeep, the defroster light blinks, the blend doors do its gyrations (all 3 of them).

I am ordering another blend door just to see if the one I got is bad but it opens and closes, just wont open for heat at times.
 
Have you checked the wiring? When it does not work keep it on and check wiring connections for power. Grounding issue, sounds intermittent which sounds like a connection.
 
jdruid said:
I know this has been discussed at length in this forum and others but I am at a loss for what else could be causing the heater/ac controls to only work 50% of the time.

What works:
- Blower works
- Speed works
- Vent selection works
- Heat / AC works 50% of the time...meaning it is a crap shoot if it will work when I start the jeep. When it works it is great.
- Heater core is hot

What I replaced:
- Coolant flushed
- Blend door on drivers side
- HVAC control unit
- disconnected battery each time

Is there something else? No matter when I start the Jeep, the defroster light blinks, the blend doors do its gyrations (all 3 of them).

I am ordering another blend door just to see if the one I got is bad but it opens and closes, just wont open for heat at times.
Click to expand...

I believe its the HVAC controls. Im in a similar situation:

What works:
- Blower works
- Speed works
**Vent selection does NOT always work
- AC works 100% of the time
- Heater core is hot
 
I had a 2008 that did the same thing. It worked when it felt like it. Removed the glove box and located a red wire and a black wire going into the blower motor. When it stopped running, I found that the red wire was dead and used a jumper wire from the battery to the red wire and away it went. The next step was to wire in a relay near the battery to power the fan. Located a fuse in the fuse box that was hot only with the engine running to activate the relay. Worked great and never had it quit again. Also FYI, the dash controls for the blower supply the ground for fan speeds and off like normal. I was told that some of the early JKs had a bad contact under the fuses but I said No way am I tearing that thing apart.
 
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Reactions: MacGuyver and Threepointsix
Barry said:
I had a 2008 that did the same thing.
Click to expand...
First, at least for me, the red made it hard to read, good info though.

It did however bring up the thought of year of jeep that you have @jdruid. 2007 - 2010 had completely different controls than 2011 and later. So, please leave some specs on your rig so we don't give bad advice because we don't know.
 
MacGuyver said:
First, at least for me, the red made it hard to read, good info though.

It did however bring up the thought of year of jeep that you have @jdruid. 2007 - 2010 had completely different controls than 2011 and later. So, please leave some specs on your rig so we don't give bad advice because we don't know.
Click to expand...
The 2008 I had was a 2 door 6 speed with the 3.8 engine.
My current one is a 2014 with no blower problems. leastwise not yet.
 
jdruid said:
I know this has been discussed at length in this forum and others but I am at a loss for what else could be causing the heater/ac controls to only work 50% of the time.

What works:
- Blower works
- Speed works
- Vent selection works
- Heat / AC works 50% of the time...meaning it is a crap shoot if it will work when I start the jeep. When it works it is great.
- Heater core is hot

What I replaced:
- Coolant flushed
- Blend door on drivers side
- HVAC control unit
- disconnected battery each time

Is there something else? No matter when I start the Jeep, the defroster light blinks, the blend doors do its gyrations (all 3 of them).

I am ordering another blend
Click to expand...

jdruid said:
I know this has been discussed at length in this forum and others but I am at a loss for what else could be causing the heater/ac controls to only work 50% of the time.

What works:
- Blower works
- Speed works
- Vent selection works
- Heat / AC works 50% of the time...meaning it is a crap shoot if it will work when I start the jeep. When it works it is great.
- Heater core is hot

What I replaced:
- Coolant flushed
- Blend door on drivers side
- HVAC control unit
- disconnected battery each time

Is there something else? No matter when I start the Jeep, the defroster light blinks, the blend doors do its gyrations (all 3 of them).

I am ordering another blend door just to see if the one I got is bad but it opens and closes, just wont open for heat at times.
Click to expand...
Check the gears behind the temperature control knob and make sure they are pushed in the way they are supposed to be. Mine had backed out causing me the same problem as yours
 
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