Compressor works but no Cold air from A/C

[steelerguy]

I went to a local A/C specialty shop to have the R12 system evacuated and a vacuum left in tact.

I installed the adapter fittings from an R134 conversion kit & it took the R134 with PAG oil & leak detector just fine. It actually cooled at least as well as the R12 for a couple of weeks.

A Couple days ago, it just stopped blowing cold air even though the compressor is working. The pressure reading on my gages reads in the green (50-55 depending on the temperature). I have also changed the Accumulator 28 psi switch to an adjustable one that I tweaked down a little per the AC shops recommendation (shooting for 20 psi). But like I said, the compressor is working but no cold air or cold piping at the accumulator.

Any ideas?

Appreciate any input.

[jocat54]

What are the readings on the low and high sides at just above an idle?

[steelerguy]

Originally Posted by jocat54

What are the readings on the low and high sides at just above an idle?

Don't have a high side gauge. Using NAPA recharge gauge for low side & have not taken it above idle. May be able to borrow gauges from autozone.

What am I looking for?

[Wheeler88]

Possibility that the valves are blown in the compressor. You need to check the high side, if the pressure is near equal with the low side pressure then thats what happened. If thats the case I can only speculate the cause of failure was to much oil in the system or an refrigerant overcharge. Was the old oil flushed from the system?

[steelerguy]

Originally Posted by Wheeler88

Possibility that the valves are blown in the compressor. You need to check the high side, if the pressure is near equal with the low side pressure then thats what happened. If thats the case I can only speculate the cause of failure was to much oil in the system or an refrigerant overcharge. Was the old oil flushed from the system?

Was supposed to have been by the AC company that did the work, but I didn't do it myself.

Would the compressor still cycle on with its valves blown?

I'll check the high side this weekend if I get a chance. Temps have cooled significantly, making this less urgent.

[Wheeler88]

Originally Posted by steelerguy

Would the compressor still cycle on with its valves blown?

Yes it will still run, just won't "pump" well if at all. I never rebuilt a compressor like Chevy uses but the valves on most compressors I've seen are reed valves. By blown I mean they tend to get a hairline crack where they flex that weakens them.

Until we see what the head pressure is, theres no telling. However if the lowside pressure doesn't change with the compressor on (decrease pressure) or off (increase in pressure(system equalizes)), is also an indication of a bad compressor.

[steelerguy]

Originally Posted by steelerguy

I went to a local A/C specialty shop to have the R12 system evacuated and a vacuum left in tact.

I installed the adapter fittings from an R134 conversion kit & it took the R134 with PAG oil & leak detector just fine. It actually cooled at least as well as the R12 for a couple of weeks.

A Couple days ago, it just stopped blowing cold air even though the compressor is working. The pressure reading on my gages reads in the green (50-55 depending on the temperature). I have also changed the Accumulator 28 psi switch to an adjustable one that I tweaked down a little per the AC shops recommendation (shooting for 20 psi). But like I said, the compressor is working but no cold air or cold piping at the accumulator.

Any ideas?

Appreciate any input.

This ended up being an overcharged system. CDJR sent me an email & advised me to bleed off some pressure on the low side. It worked.