Caravan AC hisses when compressor disengages
 

97 Grand Caravan with front and rear AC - recently there's 5-10 seconds of hissing from the front and rear evaporators when the AC compressor disengages. Seems to work fine otherwise. What does this mean?

Thanks,
Sixto
93 300SD

the switch is going out... they're all like that, i think...


no ideas on how to prevent it, other then with limited use. no ideas on replacement either

~Nate

Equalization ...quite normal...although manufacturers try to reduce the problem...the orifice/expansion valve has a small hole and the hi side and lo side are balancing out.



.

Thanks for the replies.

Switch = could be the vaccum actuators but why would there be a corresponding sound from the rear evaporator area?

Expansion valves = you're saying it's not pending failure? It would be too much of a coincidence that both expansion valves degrade at the same time.

Sixto
93 300SD

My 1996 was doing the same thing prior to my servicing it. I went through the troubles detailed in this thread:

http://www.peachparts.com/shopforum/showthread.php?t=159315

After replacing the expansion valves and the properly charging the refrigerant the problem was gone. I suspect you are getting low on refrigerant or your expansion valve is not closing tightly enough.

The TXV hiss is "normal" however oftentimes a low charge condition will cause it to be more pronounced. You might want to check your charge.

My mom has a '99(I think) Town & Country, which is essentially the same vehicle, and hers started to hiss and a few weeks later she complained of it not getting cold enough. I put my gauges on it and I think I remember adding at least 2 twelve ounce cans in there and all was good with no more hissing. I'd check the charge.

as stated above its normal. "pressure equalization"

Expansion valves never close off completely. There is always some type of small bypass hole to allow refrigerant to continue to flow because it carries the oil for the compressor.