pHEnomIC

iTrader: (14)

I did a complete A/C overhaul and it just isn't cold. It was evacuated a long time ago.

I got a brand new compressor, drier, orifice tube, and orings.
I flushed the lines and all. I then put 9 oz PAG 150 in the system, half in the compressor, half in the drier. I vacuumed it at -30 for 2 hours. It held the vacuum just fine. I then added 2 12oz cans of r134.

The compressor turns on at times but isn't on all the time which I understand is normal (cycling). I checked my pressures and the low side is 30 psi and the high side is just under 50. It is possible that i didnt get enough of the r134a in there as I didn't weigh the bottles before and after. Should I keep adding more of the r134 or do you think I have another issue?

Majestic9C1

iTrader: (19)

24oz of R134A is required.. which you put in.. so dont add anymore unless you think there is more in the cans..

Blowerman

Did you put the oriface tube in backwards? I've seen it happen.
Highside should be around 200 psi or more.

fleetmgr

The compressor shouldn't cycle at all when it's first turned on.

Based on the oil charge required for my 96 T/A, I'd say your problem is WAY too much oil, like about 5 ounces too much. For a system the size of your A/C, that's a huge oil overcharge. It's enough that you may have already killed the reed valves in the compressor.

1 FMF

iTrader: (1)

when you use small cans, such as those 24 ounce'rs or smaller, you never get all of the r134a out of it. what comes out of that can is based on pressure differential between the can and the system, which is why filling the system that way is not the best way. so he really does not know how much is in there.

first question is, you said vacuumed down to -30. that said tells me you have a cheaper vacuum gauge which doesn't give resolution to microns and you may not have all the moisture out of the system. here's one page explaining- note the difference between 29.1" amd 29.9" of Hg vacuum that can make all the difference in the world and my guess is your gauge at best does +/- 1.0" or that you can visually read anyway. so for getting moisture out, you don't "know". the only good thing is at least it held at the same reading.
http://www.yellowjacket.com/content/...e%20Vacuum.pdf

based on the 30 psi low pressure and only 50 psi high pressure you either have too little r134a in the system, or a bad compressor.
let the system sit overnight, don't run the engine, so everything is ambient temperature then take a static pressure reading of the ac system (everything off nothing running), high and low side will be equal. at 70°F you should see about 70 psi, at 90°F ambient about 82 psi. if it's less then you definitely don't have enough r134a in there- but beware this does not nor will ever tell you if you have enough. i would not add anymore oil, i don't think you are way over i thought it was 7oz or 9oz total for 4th gen f-body and even if you were would not cause the pressure problem you have. and the compressor should not cycle, it's a variable displacement so the clutch should always stay engaged and the compressor should run. if it cycles off then it's because the low pressure switch is tripping, or high pressure or pcm is commanding it for some other reason which you might have to troubleshoot. if you see your low pressure gauge go below 30 then most likely that's the case. i would just add r134a and monitor your high/low pressures, keep the r134a can warm and initially upright so it draws gas not liquid, as the can gets empty you can briefly turn it upside down. but hopefully on your initial filling with compressor running you did not draw from a full r134a can upside down because that will draw liquid and that liquid can make it to the compressor and break it. and hopefully during your initial oil fill into the compressor you then spun it well by hand to distribute oil.

hrcslam

I agree with 1 FMF with a couple exceptions.

30 PSI low side and 50 PSI high side tells me you are very low on refrigerant. In any scenario your refrigerant pressures would be higher if you had the correct amount of refrigerant in the system.

Cycling of the clutch is absolutely normal, even though these pumps may be variable displacement they will still pump the high side too high which will turn off the clutch and let the pressure bleed down some. Then turn it back on. It will also turn off at a certain %TPS for WOT runs and at a certain RPM as to not over rev the AC Compressor. If the low pressure side is too low it'll turn it off to prevent damage to the system.

It seems you have low refrigerant. If you put 24oz of r134a in the system and your pressures are that low you have a leak in the system. I've had this happen before, I would pull vacuum fine, but once I charged it nothing. It's a pressure leak.

I found this by applying pressure to the system and looking for bubbling/hissing throughout the system. Once I found the leak I replaced the seal and pulled vacuum again.

1 FMF

iTrader: (1)

i also agree with a leak under pressure being the most probable cause. and you're right with only 50 psi on the high side more than likely he is too low on r134a rather than a bad compressor.
now, hopefully you put some dye in the system, check all your hose fittings your hi/lo service ports and the compressor case for signs of it to find the possible leak. if no dye, then try adding more r134a that has dye but no pag oil. don't add any more oil.
it's possible you didn't simply tighten a fitting completely and it leaked under pressure.

pHEnomIC

iTrader: (14)

Thanks for the help guys, i threw some dye in and found a crack on the high pressure pipe. It briefly held 160 psi high side when i added more r134a and was blowing quite cold so there is hope

Im going to get a new tube, switch it out quick, repull vacuum, and then recharge.
I won't need to replace the PAG oil and the accumulator again will I?

fleetmgr

No, you should be fine.

Bigbee

+1 on the variable displacement compressor that does NOT cycle on and off if working right. I thought something was wrong with mine until I learned this fact.