necros9828

Hello fellow thirdgeners,

I haven't posted in a while, but I have some A/C questions. I'm up at the T/A Nats this weekend. Before I left for the trip, my A/C ran nice and cold. I never put a thermometer in the dash so I don't know what the exact temp was, but it was plenty cold. Well, I had the urge to take off the blue low pressure cap (previous owner converted to 134a). From just recently refilling R134a in my daily driver, I didn't expect anything to happen by just removing the cap... unfortunately I should have just left it on ... because after I removed it, refrigerant inexplicably started hissing out. Crap! I put the cap back on and the hissing only lessened but it was still leaking. I rummaged around for my line wrenches and tightened the fitting and it was STILL leaking out. WTF? After a while of head scratching, I tried actually loosening the fitting, and the hissing stopped. Apparentley the fitting was so tight it actually pushed down the pin in the center of the valve and the blue cap was all that was holding it from leaking out. OK, no problem, leak fixed. BUT now most of my refrigerant was gone. I went out and bought some of that "id" brand refrigerant with the oil included, ran the A/C at max and put about 20 oz back into the system, raising the pressure up around 35 or 40 psi. At first the compressor was cycling on and off quickly from low refrigerant, but this stopped after I filled up the system. However, the air was hardly cold anymore, it pretty much sucked.

I read some of the A/C posts and wondered if the problem was too much oil and not enough refrigerant, plus the pressure at 40 psi was too high. Other posts stated the pressure should be 30 psi. So I let out some of the oil/134a from the low side valve, dropped down to about 20 psi and then put in maybe10 oz of 134a WITHOUT the oil. OK, the pressure is good now, the air is even a little colder, BUT it's still not as cold as it was. Plus, I notice that as soon as the RPMs get up to about 1500 or 2000, the compressor starts cycling on and off rapidly. Less than 1500, it stays on all the time. What kind of mess have I gotten myself into? Should I just give up and have the system vacuumed out and start over with proper ratio of oil & refrigerant (maybe even try the Auto Frost brand?) I don't understand enough about the A/C system and have reached the point of diminishing returns in terms of effort and money spent on 134a. My bottom line questions are: Can I do something further, easily, that will restore the proper temp when the A/C is on? And is it normal that the compressor is cycling rapidly ONLY at 1500+ RPMs? It would be nice to get it cold for the rest of my road trip. If not, perhaps I'm doomed to going in for professional service after the trip is over.

Thanks all...

Reid Fleming

iTrader: (2)

If I had to wager a guess, I'd say you have too much in there and the high pressure switch is kicking in to cut off the A/C.

If you're happy with R-134a, it wouldn't be too hard to vacuum it out and put a proper measured charge back in. The stuff is cheap and easy to buy. Figure $50 to vacuum it out.

Autofrost depends on which system you have. The 406a is for R-12 systems. The X-8 is for R134a systems. Don't mix them up!

necros9828

Thanks for the quick reply. I may stay with R134a. A few more questions come to mind:
After the vacuuming procedure, what's the proper amount of R134a and PAG oil for an empty system? I see the oil comes in 2 oz containers. If I've read other posts correctly, when I begin to fill an empty system, I need to disconnect the switch on the side of the accumulator and jump it so the compressor stays on long enough to suck the oil & refrigerant in, correct?
Does vacuuming include a boil out also? If not, should I ask for this if I didn't have any problems before with moisture?
Is all R134a created equal? I see name brands that are a few bucks more expensive than the auto-store generics. Is it all the same?
As an aside, my compressor has always been, well, loud, and quite a drag on the engine. At idle it has a fair amount of squeak (not belt slip, something less loud than that) and it makes the car sound kind of like a vacuum cleaner. I hope this is normal based on other accounts of these being pretty noisy units.

Reid Fleming

iTrader: (2)

As far as I know, you shouldn't need to add oil after vacuuming the system. Vacuuming it is what takes out the moisture from the system. I could hear the moisture gurgling in there when I had mine vacuumed. You would need oil after taking the system apart and flushing parts out. Or from swapping a compressor out.

I would just stay with normal R134a myself. No need for some fancy R134a PLUS SUPER DUPER COOLING marketing rap.

If you have the R-4 cycling compressor in there like I do, yeah they're a bit on the noisy side. I find my A/C makes a more noticeable power difference when it's on than my wife's Blazer does when her A/C is on.

rideon1200

Find a friend, relative or small a/c company that is a HVAC tech. Let them handle it, will take about an hour. 134 is moisture sensitive. Also you need to replace the scrader valve, the one in the car is messed up, proably the plastic gasket. It will save you alot of headache and get you back in cooling.

necros9828

Thanks for the replies. I'm back from the Nationals now, and luckily the cooler air as I headed east back to MASS precluded the need for A/C, and I kept the windows open for the most part. I'll look up a good shop around here and take it for vacuuming at some point. I'll also research that valve.