Angry Johnny

If the compressor came apart all that debris goes straight into the condenser and there can be a lot of it, no maybe about it. GM's orifice tube system would clog up the orifice when the compressor failed. You had to replace the condenser and flush the lines and replace the accumulator/drier to fix it. Anything that is in that condenser that will still move goes straight to the drier until it overloads and comes apart. Then it goes to the H valve and then the evaporator. If there is enough debris it travels right back to the suction side of the compressor.

This is what screwed me up, debris kept loading up the drier and then the H valve because you can't get that stuff out of the condenser.

bigragu

When my compressor clutch locked up awhile back, I was lucky enough to have a spare belt in the tool box, that bypassed the A/C to get me home. After the whole process of capturing the R12, and replacing the compressor, I first flushed out the best I could, of what I could. Did notice speckles caught up in the filter/dryer. After that I re installed everything, pulled a vac, refilled the system, then ran it with the original filter/dryer for a week.
Then pulled all R12 out, replaced the filter dryer and expansion valve for new ones, then refilled the system.
It's a lot of work, plus taking up the time of a buddy who has the R12, but in the end, I had better piece of mind about the darn thing.

edwinsmith

Everything is new except for the evaporaator. Nothing is plugged and evaporator and condenser flow freely. I may have another problem such as a wrong expansion Valve. If I reducation the charge until the pop it valve doesn't blow then the low pressure switch cycles on and off. Going down the road it cools but seems like it should be cooler

Edwin

bigragu

I've always heard, that a system overfilled by refrigerant will not have the same cooling effects as a system with the correct amount. Same with the compressor oil. Too much can take away the cooling.

Angry Johnny

The compressor is supposed to cycle on and off. How much refrigerant are you putting in it? I think I only put about 2-2.5 lbs. in mine.

edwinsmith

I'm trying to put in enough r134a to keep the low pressure switch from cycling.

On some systems, the compressor will cycle on-off with temperature of the air coming out of the evap. They are NOT supposed to cycle because of the low pressure switch. The low pressure switch cuts off the system when the refrigerant gets low to prevent damage to the compressor.

AFAIK there is NO temperature cycling feature on the factory air system. The temp is regulated by mixing warm air from the heater. (Seems like a stupid system but it is what it is.)

If my condenser is the correct one for R134a which I haven't been able to verify yet because I've been on the road, then perhaps I need a different expansion valve.

What year did Dodge change to R134a? If those parts will fit my truck then I need those part numbers.

Thanks for the suggestions everyone.

Edwin

Angry Johnny

The heater control valve is off in the max a/c position, so there is no warm air. You are right about the low pressure switch though, that is strictly to protect the compressor if the refrigerant is low. There is nothing in that system other than the cycling switch to measure the temperature of anything coming out the vents. If the compressor doesn't cycle and the ambient temp is cool enough to let it, it will simply freeze over.


Here is the cycling switch. It has a probe on it that slides into the suction tube. Sometimes pulling them out will result in colder air and less cycling. Chrysler had been using them since the late 70's when the old RV2 compressor was no longer used.
I tried to get a better pic but my camera batteries died.