I have a 2007 Chrysler PT Cruiser. AC works when driving but not when idle. When idle and AC is on, the car rumbles about every 10 seconds but doesn't when AC is off.

It sounds like the engine speed is too low to run the compressor.

Compressor is weak. If you increase engine speed and it blows cold its a little low on charge or your ac comprssor is at fault.

the rumble cycling is engine torsion mounts upper and lower and possibly engine mount front.

If you didn't yet get your problem solved, it is the fan. My daughter had same problem, as did her friends mother with pt cruiser. The fan or the fan relay switch isn't working, so when the a/c tries to turn it on, it pulls power and idles very rough. New fan, problem fixed.

Lisa hit the nail on the head. The problem here is that your radiator fan unit needs replaced as the OEM fans in these vehicles are known to be problematic. The issue is that the low speed on the fan has died but the high speed is still ok, which prevents the engine from overheating. Since the low should ALWAYS be engaged when the A/C is running, there's a simple check to see if your fan is the culprit. With your engine cool, turn the car on and turn on the A/C. If the fan is NOT spinning, it needs replaced. (It’s important to do this check on a cool engine, otherwise the fans high speed may kick on causing you to think that the fan is working properly). This check should also be performed fairly quickly as I don't recommend running the A/C without the fan for prolonged periods. The reason for this is because when the fan isn't spinning, there is not adequate air flowing over the cooling fins to remove the heat from the refrigerant. When this happens, the A/C system builds up excessive pressure and socks the compressor which makes it hard to start. The reason the engine idles rough is because it's being bogged down while trying to run the compressor in this state. You should also know that when excessive pressure builds up in the system, it will vent some R134 (the refrigerant) to relieve the built up pressure and prevent damage to the system. So obviously, if you continue to run the A/C in this state you'll eventually need to add refrigerant. If you’re wondering why the A/C works when the vehicle is in motion, it’s because the air entering the grill from the highway is passing over the cooling fins and thereby doing the work of the fan and cooling the refrigerant. Replacing the fan yourself should take somewhere around 90 to 120 minutes. The actual part costs around $100 and there's a decent YouTube video out there that shows how to do it. (http://www.youtube.com/watch?v=EwquTLC2Ink). This DIY repair is well worth it as I've heard some people say they were quoted around $800-900 for the repair at the dealership.

This is exactly what my car is doing. Can I tell if the fan is spinning without removing any parts? Where do I look?

Thanks bill you submission has been a tremendous help

Thank you Bill

I got the same problem. Replaced the fan. It ran ok for a couple days. Now same thing again. The fans not coming on and rough idle. Help please

Bill and Lisa, Don't be so sure it's the fan. You might make an expensive repair that was not needed. I had the exact same problem with my 2007 PT cruiser and it turned out to be the low speed relay switch. We pulled the top of the relay switch and engaged the solinoid with a screw driver and the low speed fan came on, so we knew t hat the fan was okay. Replaced the Fan Relay switch for about $14.00 and everything works fine.

Had the same problem plus engine light every now and then. Changed spark plugs. They were very bad. Works great now

Fan a problem yes, after much testing, car side fan connector was bad, PCM ground signal was not getting through it! (Black wire)...2 Blue wires are Hi speed and Lo speed power lines...Connector looked fine....but would not pass the ground signal... $58 from Chrysler for new 3-pin connector !!! AHHH no, I just hard cut the fan side connector off also and hard wired the fan...been that way 4+ years no problemo...Well. until recently when a new fan was actually required!!! hardwired it again, no problemo...

If it does it only with the A/C on it’s the fan. The refrigerant building too much head pressure and will put a hell of a load on the engine after a cycle or two.

Dealing whit the same problem, first I changed the fan ( it came whit its relays) and today I put a new OEM low pressure swicht and still the same. Today is being a realy hot day and as soon I turn on the ac it turned my car off, any suggestion? No overheating, no check engine light, runs ok w/o ac. Cooling air when the car is could and ac works ok for about 10 min and them idle star coming and go untill car turn off, so that meke me thing that the ac compressor is working.

I've taken my car to the shop 3 times to correct this problem and the 1st time it was some hose, the 2nd time it was the brake booster, the 3rd time was the idle control valve. $700 later I still have the same problem only worse because now the water pump is leaking. Will somebody PLEASE HELP ME???