Diagnosing A/C Problems

[lincolnshibuya]

How much oil did you put in it and what kind?

Calls for 9oz of PAG46 without rear a/c and 13oz PAG46 with rear a/c.

did that per the compressor's instruction.

 

[Reklaw]

I know this thread go a little off topic but I figured I'd keep posting with my trouble shooting. Same results as before. I hooked the gauges up and about 30 low side and around 100 high side. I unplugged the sensor and jumped it so the compressor would stay running and the pressures did not change much. I waited until the high pressure line got noticeably hot and then checked the lines right by the firewall and they are the same temperature. Upon further inspection, the high pressure line is hot enough that you can't touch it running into the condenser and it is ambient temperature coming out of the condenser. My conclusion is that there is a blockage in the condensor? What is your guys' opinion on that?

 

[Reklaw]

I'm not sure if anyone is still reading this but I want to keep it up to day to help people in the future. I ordered the compressor "kit", and condenser from Rock Auto. They arrived on Thursday so in the afternoon I cracked open the system. Followed the instructions in the good old haynes manual for removing the condenser and replaced that. Finally got the orifice tube out and found metal shavings on it so I confirmed that was at least part of my problem. Pulled the accumulator and got the new one ready to go in. I had a bought a can of a/c system flush from advance auto and proceeded to flush my evaporator. Well, that little can was clearly not enough. So I called around on Friday morning and found one to rent and bought a quart of a/c system flush. Got it home, hooked up the compressor I barrowed from my dad and flushed the evaporator until I had clear liquid coming out. It was very flourecent green. I then continued to blow clean air through the line every time the compressor got back up to full pressure so that I could get the most solvent out of the evaporator as possible.

Getting the a/c compressor was a paint. I couldn't get the stud out. Finally I figured out an acceptable was to get them out and when I tried draining the oil from the compressor it was almost completely empty. Now that the compressor was off the car I flushed the other a/c lines and proceeded with the new compressor. The new compressor had 5.4 ounces of oil in it already so I dumped it out and made sure I had 9 ounces because that is what is listed on the radiator shroud. Reinstalled the compressor, new serpentine belt while I was at it, hooked the lines back up to the condenser, put the new orifice tube in and connected everything up, checking the o-rings and oiling them up in the process. I then got my gauge set and vacuum pump ready to pull a vacuum as I am paranoid about letting humid air into the accumulator. Last thing I did was connect the accumulator and then immediately pulled a vacuum. System held a vacuum and the needle did not budge for at least a half hour while I cleaned up. I had to stop the process at that point last night so i'm going to vacuum the system for an hour this morning before I start the recharge process.

 

[TechGuru]

Recharge by weight not pressure. Use pure R134a without added crap. Preferably DuPont Suva.

 

[Reklaw]

I know this update is 2 weeks late but as they say, better late than never.
I had been using plain old 134a from Advance, the carquest stuff in the can with the blue label. I had an empty can so I used my kitchen scale to weigh it and then could zero it. I also weight the can tap so I could zero as much as possible. Now, the kitchen scale I was using was just a cheap one from walmart but a 12 fluid ounce can of 134a came in weighing 12.3 ounces of material so I figured that was pretty close.

With a 2x6 laying across my airbox for the scale and everything hooked up I started adding the refrigerant and jumped the cut off switch to force the compressor on. After I no longer had to jump the cut off switch any more I got my wood working bar clamp out and set it up to keep the engine running at 1.5k and put the 3rd can in. I now have ice cold a/c. Just took a trip from Pennsylvania to Tennessee and had ice cold a/c all the way there and back.

Thank you to everyone for all the help and I hope this thread can help many others along the way.

 

[Hugh Janus]

Great write up!