Automotive Air Conditioning Information Forum (Archives)

Larry-Cleveland on Sun May 29, 2011 11:29 AM

Year: 1983
Make: Ford
Model: Thunderbird
Engine Size: 5.0L
Refrigerant Type: R-12
Ambient Temp: 72
Pressure Low: -25
Pressure High: +125
Country of Origin: United States

Hi guys, my first post so be kind

My 1983 T-Bird locked up the compressor about 10 years ago. Yes I am a bit slow getting to my projects! The system was working fine and the compressor just locked up one hot day.

I purchased a rebuilt compressor (F6 model I think), from eBay. I drained and measured the oil from the old compressor, almost 3oz. It looked nice and light colored. Yes the system still had it charge in it.

I drained the oil from the new compressor and added a total of 3.5 of new oil back in.

The system pulled almost a 30 vacuum. I kept it on for 24 hrs.

I charged the system with 2 pounds of R-12 (getting to the last of my old stock) on my Dial-a-Charge. The charge went in EZ. Tested for leeks with my electronic tester, looks good.

The system did not get cold when charging, I was only using a box fan and was thinking it was not getting enough air movement. Took it for a ride……only warm air. All the lines are warm under the hood too.

The next day I hooked up the gauge set, 75 low and high. Started car with the box fan going, high was +125 and low was -25. Yes negative pressure on the low side!

I check for leeks, none found. I added ½ pound of R-12. The low side came up during charging but then right back to negative pressure once it was in, and yes still warm air.

I am going to a car club drive of 1,000 miles this week and AC would be nice.

I hope you can help!

Thanks Larry

Dougflas on Sun May 29, 2011 1:25 PM

I don't have a manual for 1983 but 1982 says 2 1/2 lbs. 1984 says 2 1/2 lbs also so I guess you need the same for 1983. Sounds like you have a restriction. I would look at the TXV. Not sure you have one but if you do, reomve the sensing bulb, place it in ice water and then your hand...see if you get different pressures. If you don't have a TXV, then look for the orfice tube to be plugged. Look for a component that freezes up rapidly. That is the restriction location.

newton5 on Sun May 29, 2011 10:25 PM

An 83 Tbird would be a CCOT system and should cycle the compressor off at ~28psi. If it's dropping into a vacuum on the low side, there's an issue with the cycling switch or AC relay.

I'm thinking the orifice is plugged with debris from the old compressor and the refrigerant is just getting pumped into the high side of the system.
I"think" the orifice is crimped into the liquid line and not removable on that car. I seem to recall all Fox chassis cars being set up like that