97 T&C - Air Conditioner suddenly stopped

My a/c seemed to work pretty well. Sometimes on the 100+ degree days I would have to turn on the rear unit to really cool it down but normally just the front a/c was all I needed.

Sometimes at idle I could hear a hissing sound coming from under the hood and sometime when the van was shutoff I would hear the same sound but since everything seemed to be working correctly I didn't worry about it.

A few days ago it was working just fine. I shut the engine off while I fueled up and when I restarted the vehicle the a/c would only blow hot air. Not even a little bit of cool.

I have verified that at idle, when I push the a/c button that the compressor clutch engages and stays engaged. With the vehicle warmed up completely and the a/c running at idle for 5 minutes both the high side and low side hoses are very warm to the touch. A cheap pressure gauge on the low side indicates about 60 pounds of pressure.

Any ideas?

Thanks!
--Doug

Take it to the pros. Find a specialty shop and skip Joe Blows gas station.

Way too much pressure on the low side, think freezing +32 as the correct pressure.

A little base info :http://answers.yahoo.com/question/?qid=20060718155308AAjfrPU and http://www.aircoparts.com/faq.htm

I agree with RIP somethings are better left to the pros.I had a small leak in the condenser and it too made the hiss noise.What I found out was the hiss noise was actually the 134a gas (now in liquid form from the pressure leak) in the ac system circulating.The compressor can't compress the liquid like it could for the gas.

I replaced the condenser myself but got the experts to check it for leaks and do the recharge.I guess I forgot how cold it should have been,must have slowly leaked over the summer.

Thank you for your input and the links.

As for taking it to a pro, the last time I had a pro work on my air conditioning system in a car, it took almost $2000 to get it back out of the shop. :eek:

I will probably just drive it through the winter and next summer when I can't stand the heat any longer I'll just trade it for something different. I can't justify to myself spending that kind of money for something with 140K miles and bleeds $4 a quart transmission fluid at the rate of a quart every 1500 miles. :)

Thanks again,

Doug

If the low side is truely at 60 psi and you have a gauge, I would (this conversation never happened) bleed the low side system down (I use a rag over the port and a small phillps screw driver to slowly release pressure), until you get into the 32-35 psi range. I have had some success with a new 134a refrigerat for older cars (say so on the can) that uses some oil and sealer, I did it on my kids 1990 BMW 325ic and it worked great, they now have very cold air and a operational system. Again you cannot do this until you get the low side pressure way down (maybe 20 psi) and then using the new stuff, slowly build to 32-35. I bought this stuff at an Advance auto parts store.

If you really have 60 lbs on your low side, that's about double what it should be. I would think that you reading the high side. If you are reading the high side your reading is about half of what it should be, and would indicate a low charge.

The high side port is right at the compressor. the low side port is on a tube that runs back to the evaporator along the passenger side wheel well..it's in real close proximity to the serpentine belt.

I would guess you read the wrong side, and that you are low on R-34. These vans are notorious for eavaporator leaks..which might explain the hissing you heard..although some of that can be a normal equalizing of pressure between the high & low sides when you shut the van off.

Spit

I can see why you're reluctant to have someone knowlegeable look at it. I'm thinking the pressure valve (my term) is stuck. Have to flush the system and replace it and the accum/drier. The A/C on my daughter's Camry would put out hot air whenever it wanted. The clutch would still be engaged and, not positive but, the low side pressure was high when it happened. The valve and $600 fixed it two years ago. It would be best to get a set of gauges and see what the system is doing both high and low side.

By any chance is the transmission fluid collecting on the top of the tranny and running down the sides? If so there's a good chance the forward pump seal is shot. Cost me $700 to get fixed ie, tranny removed, seal replaced, tranny installed. I lived with the leak 4 years till the wife put her foot down. Gotta keepem happy.