Air conditioning runs warm sometimes at stop light

[mytc05]

Hey all,

Wanted to see if anyone else has had this problem, and if so, knows what might be causing it. Sometimes (especially in the first few minutes of driving) my air conditioning will run hot when I'm driving slow or sitting at a stop light. Sometimes it has started cooling down fine after a minute or so of driving, but then when I pull up to a stop light, it goes to full hot air again. Putting it in neutral at the stop light and revving it up doesn't seem to make any difference. Has anyone else had this problem? It never used to do this. Could this be an alternator problem? I only ask that because I've had another thing or two make me wonder if my alternator might be slowly going bad. It almost seems like maybe the compressor shuts off when this happens or something and stops the air conditioner from running. If the car has been running for a few minutes or so and cooled the air down to cold, then it doesn't do it anymore. Any suggestions?

[Nile]

I don't think an alternator issue would affect whether or not the compressor is working.  It could be as simple as not having enough freon in the system.  Make sure you have the freon pressure checked before adding any and if the pressure is too low, make sure you use the correct freon (eg: has your car been converted to 134a or is it still R12).  It's also possible there may be some electrical connection somewhere that needs to be cleaned - not that our TC's ever experience this.

[Reaper1]

I agree. It's either low on freon or the blend door is sticking/stuck either due to a mechanical issue or a loss of vacuum. There's 2 hard vacuum lines that go to the HVAC system from the engine. I believe the grey one is the one that feeds the door actuators. It's common for one or both of these to get brittle and break under the hood. Just something to check...

[mytc05]

Hey guys. Thanks for the responses. It's good on Freon. It had a leak a year or so ago, and we fixed the leak and refilled it (we had already converted it to 134a). I checked it again a couple weeks ago, and it's still full. Realized this week my TC does indeed have an alternator that is going bad. Going to have to replace it, and I'll see how it does after this. If it still happens after that, I'll take a look at the blend door. Thanks again guys!

[mytc05]

On 8/15/2018 at 12:57 PM, Reaper1 said:

I agree. It's either low on freon or the blend door is sticking/stuck either due to a mechanical issue or a loss of vacuum. There's 2 hard vacuum lines that go to the HVAC system from the engine. I believe the grey one is the one that feeds the door actuators. It's common for one or both of these to get brittle and break under the hood. Just something to check...

 

Hi Reaper1,

Picking up on this as it's still been a nagging issue on a hot day. We did end up replacing the alternator shortly after my last post, but that hasn't made any difference for this. I did take a look at the hard lines, and they seem to be in good shape. No visible tears or dry rotting on the hoses or holes in the metal portions. Any other suggestions you might have? Is there another easy way to troubleshoot the blend door or another issue that might be causing this problem in the system? Again, as long as I seem to be driving, it seems to be fine, but when I idle at a stop light or in traffic, it seems like the compressor shuts off or something and the air gets warm until I start to drive again. 

Edited May 19, 2020 by mytc05 (see edit history)

[Hemi Dude]

If the radiator cooling fan is not working, remember the fan relay? Well, anyway, if the condenser begins to get too hot, the A/C system cannot function properly.

Have you checked to see that the fan comes on every time the compressor clutch is engaged?

[mytc05]

Thanks for the recommendation Hemi! Next time I've got it out on a hot day, I'm going to check this out. If the fan isn't kicking on when it should when the compressor runs, then I guess I'll take a look at the relay first and see if that fixes it. Fingers crossed I can get this pinned down soon!