A/C hisses, spurts steam

Early last fall, I was driving along - or rather, sitting still on the highway waiting for traffic to move, on a hot, humid day with the air
conditioner running, when I suddenly heard this sputtering hiss and a puff of white smoke or steam coming from under the hood. I looked at my gauges, and the engine temperature was spiking - moving up very rapidly. I immediately turned the A/C off, the heater on full, and started looking for a place to pull over onto the shoulder. The temp immediately began dropping as quickly as it had risen. So I drove it to the shop. The temp had gone up so fast, and had come back down again, so fast, that all I could figure was that the coolant had stopped circulating entirely, then started again. So I wasn't at all surprised that the shop told me I needed to replace my water pump and belts. Turned out that that was the last hot spell of the year, and I never ran my A/C again, after getting the car out of the shop, until this spring. As it got warm again, I turned on the A/C again, and again, on occasion, I've been getting the hiss and spurt of white smoke or steam. when it's hot outside, when the engine has been running long enough to reach full temperature, when the A/C is running, and when the car is stationary. The difference between this spring and last fall is that the engine temperature isn't moving at all - it's staying exactly where it should be. So it appears that the water pump was the cause of the temperature spike, and that the his and puff of smoke is something else that just happened to happen at the same time. Any ideas as to what it is? I hadn't connected it to the A/C, last year, because I couldn't see how the A/C could have anything to do with engine temperature - aside from being an additional load on the engine. But the incidents this spring have happened only when the A/C was running and the car wasn't moving. I'm at a loss. Help would be appreciated.
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Could it be that the aux electric radiator fan isn't kicking on with the AC? My last car had two fans. One runs normally with the thermostat, the other whenever the AC is on. If the car was stationary and the AC was on, it needed BOTH fans to handle the heat. Especially if the car was just 'highway driven' and I came down to a stop and there was a lot of residual heat in the motor.
I'm not sure how my fans work in my current car, but I do know there are two of them, and normally only one cycles on and off if I'm running the car stationary in the driveway with the AC off. I suppose it might be a good idea to try it with the AC on and see.
Another thing to look at is the radiator itself. I had an 85 Dodge that started overheating. Using the AC was out of the question. It go so that in April when the seasons started to warm up it was fine on the highway, but when I took an exit ramp the tem shot skyward as I slowed. I had to turn the heat on full blast in the car.
There was a Goodyear shop half a block from where I worked. 4 trips there and one $50 charge and it still was a mess. I ended up hitting a local radiator shop and he took 30 seconds to find the problem. All the fins were rotted away on the radiator. Still there, but nothing but rot. With no leaks. A victim of New England road salt. The radiator just couldn't blow off the required amount of heat unless there was a lot of air flow.

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Im at a lost just as much as you are because I have no idea what the year/make/model is?
Glenn Beasley Chrysler Tech
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On Fri, 06 Jul 2007 13:17:28 -0400, maxpower wrote:

2003 PT Cruiser
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Jeff Dege wrote:

Sounds like the compressor is either locking up or loading up heavily so that clutch is slipping, or the belt itself is slipping. Does the "smoke" smell like burning rubber (belt), or hot metal (compressor clutch)?
Start with the simple stuff- check the tension and condition of the AC compressor belt.
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On Fri, 06 Jul 2007 14:06:32 -0500, Steve wrote:

Neither. No smell, and it looks like steam. A puff of white that dissipates quickly.
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Jeff Dege wrote:

One thing to consider: The cap on the pressure bottle. They can start leaking but not leave much evidence. You might want to replace that - get it from the dealer - not aftermarket. Not too expensive, and should be replaced periodically anyway, so just do it with the possibility that it could be contributing to or causing the problem. Once you lose the pressure that enables the coolant to go well over normal boiling temperature, things get nuts.
Also - running the a.c. presents a much bigger thermal load on the engine and cooling system than I think you realize - it usually is what pushes the cooling system over the edge when there is a problem that make the system marginal.
Fan operation? Thermostat?
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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Jeff Dege wrote:

Odd. The only thing I can think of is that maybe the high-side relief valve is opening allowng a burst of R-134 to blow out. There would have to be a secondary cause for that, though, such as a cooling fan that isn't working. I've never owned a PT, but in general if there are 2 fans, make sure they're BOTH working, and if they're 2-speed make sure that they actually work on low speed and aren't waiting until the system says "ouch!" to turn on only at high speed (been there, done that with an LH car).
Oh, and if it IS blowing off refrigerant, you should see an oily residue near the relief valve, and you now probably need a recharge too.
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my
rapidly.
"smoke"
The PT only has one fan motor. The ouch would be as soon as you turn the A/C on. It does not turn on at a certain temp or pressure. It turns on at the request from the A/C control.
Glenn
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maxpower wrote:

That's a step backward! Our 93 LH fan is controlled by high-side AC pressure and coolant temp. If the engine is warm enough, the fans come on low, if the engine gets hotter, they come on high. Same with the AC- when the high-side pressure reaches a certain level- low fan. High side pressure hits a second threshold- high fan. I always liked that system because the fan is never arbitrarily on, its always on because it NEEDS to be on, and cruising down the highway it may never need to turn on.
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More then likely your cooling fan 2 stage motor is only working on the stage that allows the fan to turn on when the engine is hot. When you turn the a/c compressor on the fan will turn on at the same time. The condenser builds up so much heat/pressure and will cause engine temp to flare. The puff and white smoke you heard was the pressure release valve blowing out your R134 to allow the temp/pressure to stabilize.Now that you released the r134 the a/c should not blow as cold, especially at idle. First thing to do is find out if the radiator fan turns on when the compressor is requested to turn on. and then make sure the system is properly charged. Whoever you have doing this make sure they do NOT use the high side port at the top near the low port or it will give them a false high side reading or a restriction diagnoses. They have to use the high side port at the compressor.
Glenn Beasley Chrysler Tech
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On Sat, 07 Jul 2007 06:00:27 -0400, maxpower wrote:

That does fit the symptoms.
Next the question.
Will this cause problems, if I don't fix it right away, provided that I either don't run the A/C, or shut off the A/C at idle?
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my
rapidly.
turn
condenser
out
thing
at
well your A/C is not blowing as cold as it should since the release valve dumped off R134. Keep in mind in the winter time when you use your defroster or a rainy day in the summer your A/C is being used to remove the moisture from the vehicle. Thus needing that fan to keep the condenser cool and the high side pressure down. And who's to say that the fan motor may completely go out all together? Just a thought
Glenn
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