QuestionThe intial startup of car.
1. AC and blower fan work fine in highway or city driving.
2. While driving for hours AC and blower fan work fine.
3. Upon entering slower city driving AC may turn off and blower fan blows hot air.
4.) Upon shutdown of car, and restart after several minutes, AC & blower fan both do noy work.
5. Upon subsequent highway driving AC and blower fan will turn on and work fine.
Thx, Jon
AnswerJon,
What may be happening is two different things.
The A/C working onthe highway but shutting down in the city. I will touch this first.
You have 2 safety switches in your system. One is a low pressure switch, one is a high pressure switch. I am going to concentrate on the high pressure switch in your case. The high pressure switch is designed to cut off the compressor in the event of high pressure. High pressure can be caused by many things. The most common of which is a dirty condensor preventing airflow from moving through it. On the highway You may be moving fast enough to forcefeed air over the condensor, so your pressure never builds high enough to shut it down. In the city, less forced air, pressure builds= switch trips and shuts down the compressor. Your condensor fan may also not be coming on. But look at your condensor (located in front of your radiator) is it covered in road grime/leaves/mud etc.? Or are more than 25% of the fins bent to a point that they block airflow? If so we have found one of your problems. Take a normal garden hose and clean it off. Force water through all of the fins to make sure they are clean. (A shop would charge you about 30 bucks to do this) If the fins are bent, you can pick up a tool called a fin comb for less than 10 bucks at most auto part stores. This will straighten the fins as you "comb" it through them.
As for your blower motor not coming back on after the car has been turned off for a few minutes, this could be many, many things. My first guess is that your fan control relay is heating up while it is in use. After you allow it to cool back down, the contacts reconnect and the fan works. Locate your fan control relay, (generally in the engine compartment relay box) and next time it does not come on, feel it. You should not feel any difference in temperature between it and the relays surrounding it. If you do, replace it. If you do not, I recommend you taking it to a reputable shop or even, dare I say it, your local Dodge dealer *shiver*, and have them troubleshoot your electrical control system.
I hope I helped you out a bit. Thanks for the question and good luck.
