Automotive Air Conditioning Information Forum

With unknown origins of some of the parts used in the previous owner's 134a conversion and issues I was having the last time I tried to charge it, I tore everything apart, flushed it all again, new blue orifice tube, new receiver/dryer(accumulator), and brand new H6 compressor. All lines also got new orings. When I flushed this time, everything was clean (even when I flushed the last time, I really didn't get any dirt, just a lot of old oil in the evap). Got it all back together today and started charging it. Ambient was about 105 and it was humid. Compressor called for PAG 46, but none of the local shops had any, and the compressor mfg stated that PAG 100 could be also used. Put 5oz PAG 100 in the receiver/dryer, and the compressor came pre-filled with 3oz PAG 46. Pulled vacuum for 30 min. Let it sit for 30 min and it held the vacuum. Started pumping in R134a. System originally called for 3.25lbs of R12, so I was targeting 42oz of 134a (52 x .80 = 42). While I was on the 3rd can, my low side pressures were already in the high 40's and the high side pressure was nearing 300. Vehicle also has a brand new heavy duty fan clutch and it is moving noticeably more air than the old one, plus I also had a fan blowing directly into the condenser. When the pressure hit about 300, the compressor seized and the clutch began to slip. I immediately shut off the A/C. At that point, I hit the condenser with some water and the pressure dropped down below 200. I started it back up and the pressure stayed low and it started taking a charge again. When the pressures would get up near 300, I would wet the condenser and could get the pressure under 200. I continued this until I got it charged, and ended up with about 44oz in. Vent temps never got better than 75 degrees. At that point, I needed to shut down for a while. Later in the evening, I fired it up and within about 2 seconds the compressor froze and the clutch slipped. Working the switch on and off, I was able to finally get the compressor to run, but vent temps were in the high 70's. I didn't have the gauges on it at the time so I don't know what my pressures were.

I don't get why the high side pressures were so high. There was a lot of air flow through the condenser - you can really feel and hear the fan working. Even when I hit it with water, I didn't get a reduction in vent temps. Something I did notice when I was flushing is that the condenser seemed to have a restriction - there wasn't as high of an air flow going through it as there was through the evap.

Any ideas? Anything I should look at or check?

Side note - when installing conversion fittings on the ports, should I have pulled out the schrader valves from the old ports?

Thanks!

I would have put 8 oz of oil in the compressor. That is where oil is needed. 3 oz is not enough in my opinion. You probably cooked the compressor.

Dougflas wrote:I would have put 8 oz of oil in the compressor. That is where oil is needed. 3 oz is not enough in my opinion. You probably cooked the compressor.

I was following the instructions in the documentation that came with the compressor. So with a total system capacity of 8oz, all should have gone into the compressor, even though this compressor does not have a sump?

Is the high side port before or after the condenser?

Yes you should remove the stock shraders when putting on converters that include their own, but the converter shrader valves have a special tip on the bottom end to push down the stock shrader if it is still installed.

High side port would be after the condenser. It is between the condenser and evap. Condenser - port - orifice tube - evap.

So replaced compressor yesterday. Flushed discharge line and got nothing and pulled OT and it was clean so I don't think I got any contamination from the compressor. New comp installed, pulled vac, and recharged. It was about 104 degrees outside, with nice monsoon humidity. With 42oz in, I had pressures of 48/295 and vent temps of 62 degrees. I'd like it colder, but a 40+ degree difference between ambient air and vent temp is pretty good. My high side conversion fitting is leaking at the schrader though, so I might be doing this again soon. For now I have a cap sealing it but I don't know how long that will last.

Thanks everyone for the help!

Throughout the day yesterday the vent temps got warmer. It is still cooling some, but not much. Actually started cycling at idle, so I think that conversion port is leaking, even though it has a cap. Anyone know where you can get steel or brass caps for the ports?

Don't guess, find the leak. One that large should be detectable with soapy water.

Found the leak. When the liquid that I thought was just condensate drain water didn't evaporate, I checked and it appears to be PAG oil. So new evaporator is on the way. And just to add insult to injury, the heater core started leaking also. And the clutch on the new compressor likes to slip if everything heat soaks for a while. So, I'll keep warrantying it until I get one that works

I'm now at the point of just ripping everything out and installing new. I also found a retrofit parallel flow condenser. That, plus new lines, plus new evap.

As I wait for my last few items (new hoses and HPCO from AC Kits!), I decided to call the compressor mfg tech line to discuss 2 failed compressors. The documentation for the compressor specifies PAG 46. When I bought the compressor, the store did not have any 46 - they only had 100. The clerk insisted in that in their training they were told that PAG 100 was "universal" and could be used in place of 46 or 150, so I used 100. When I told this to the person on the other end of the phone, I thought he was going to explode. The response was NEVER substitute anything and always use the oil that is recommended by the compressor manufacturer.

Fun times.