Really? A/C Compressor Stumble Is Normal?

[quicksilverdon]

My vote - ignition wires - replace plugs also.
Agree w/Mean Green - the stock wires are crap, and added load on engine is when the spark falters at idle. On both my PTs the stock wires started to go before 20,000 miles - I replaced w/Crane wires - www.RaceAndStreet.Com and was set.

Not a big investment and you should do it anyway....

[NewPTCruiserInPA]

Would wires & plugs cause problems with the A/C, in addition to the shudder?

[cleverklutz]

Plug wires shouldn't make it blow warm air. I would say call up the dealer again. Sounds like you have the rare find of a good dealer.

Good luck,
Ben

[NewPTCruiserInPA]

I called the dealer and we're bringing it in again on Monday. They said they've never had one with this problem before, yet I've found a bunch of threads on the internet with this same problem (and I'm printing them out for them to look at, lol).

Unfortunately, it seems like no one ever updates with the final outcome on how they fixed it (or IF they fixed it). Hopefully my dealer will be able to fix it, and I will be sure to update. They know it's not the compressor, at any rate!

[NewPTCruiserInPA]

Another thing we noticed: when in idle the RPMs is about 800. when it does it's shudder/shake with the A/C on, it will do a short jump up, like 200 RPM and then fall down just as quick to 500 RPMs before bouncing back to the normal 800. It does this every time it does that. Does this mean anything?

[sawdust123]

I had the same problem. It turns out the answer was a fouled spark plug caused by a leaking valve cover gasket.

The stumbling was more prominent with the AC on but as the problem got worse it happened with the AC off too. I replaced the wires but that didn't help. Then I pulled the plugs. The original plugs looked good but one was covered in oil. It turned out the oil was dripping into the spark plug well and down the plug threads until it fouled.

[NewPTCruiserInPA]

If I tell them I would like the wires and plugs changed, are they just automatically going to replace with the same kind? Will I need to supply them, or do they have better options if I ask for one? I guess you can tell I know zero about cars, lol!

As for the blowing warm air in idle, I am wondering if something is stuck somewhere. If you get in the car and turn it on it will blow warm air until you are driving (when it does the shudder/shake, but when it isn't it blows cold). Once you are driving around for a while, it will still do it's shudder/shake at stops, but the air will stay cold during it. Maybe if you sat for a longer period of time than the couple seconds/minute at a stop sign it would start to blow warm again, but it doesn't get the chance.

[Camaron32]

Please post when you find out what the problem was. It sounds exactly like what is happening in my 2006.

[ptlvr]

When the dealer replaces plugs and wires he will use the same factory junk as what is in there unless you supply them yourself.I live in Northeast Philly and replaceds my stuff with bosch double platinum plugs and high performance wires from Autozone and havent had a problem since.

[Cal Cruzer]

Originally Posted by NewPTCruiserInPA

And now, to top it all off, when the car is in idle it blows hot air! When you are driving it blows cold. At least BEFORE we took it in to get looked at it blew cold air in idle! So every time you come to a stop sign it blows hot, then cold in drive, then hot when you stop again.

It could be a couple of things.
1. It may be idling to low to spin the compressor fast enough to circulate the freon. I would really recommend doing the wires and plugs. This is such a common thread with most PT owners that it is the first thing we jump on.

2. Just because they replaced the compressor doesn't mean they found the leak. If they didn't perform a dye test (introducing dye into the system that shows up under black light at the leaking points after the system has been run) then you may still be leaking at a hose or connection.


Your cars computer is programmed to raise the idle when the AC turns on. There is more drag in the engine when the AC clutch engages and this is supposed to compenstate. If your freon is low, you have a pressure switch that automatically switches the compressor back off so it doesn't burn it up. You could be in this constant loop of having just enough pressure to turn the system on, having the computer see that and bump the idle then the pressure switch turns it off again etc, etc, etc. At speed the system may be turning fast enough to keep the pressure up and the compressor running. Even though the computer can react quickly enough the mechanical part (the engine) just doesn't respond that quickly at idle.