2nd Gen Non-Engine/Transmission A/C that works only about 25%!

[ralee]

Hi Again,



My AC works only very marginally. Here`s the lowdown. Truck is idling fully warmed up with the AC blower on high and temp knob turned all the way cold. The compressor is activating the clutch for about 4 seconds and then disengaging for about 5 seconds. I have a psi gauge on the low side schrader valve and it shows 25 psi when the clutch is engaged and 45 psi when disengaged. It would behave this way forever and at the same time blow only 80-85* air. Is it possible to not have enough R-134A in there and this would cause the engage-disengage thing? Or, ??

Does anyone have any ideas? Oh yes, it is about 80* outside.

Richard

 

[jhoughton]

You need between 35-40 while the compressor is runnung. You are definantly low on 134A. Most auto stores sell service kits or just the freon. If you are able to check the high side I believe it should be somewhere around 250-275 psi. Anyhow add some freon and you will notice a differance.

 

[ralee]

Jhoughton,



I have read that one cannot add freon successfully without the compressor clutch engaged so the compressoor is running and compressing. This being so, I would seem to only have that 4 second span of time to inject freon. The freon R134A kit that I have comes with a hose assy. that has a gauge and a push button to control the flow of freon so this would be possible. Question is, would it be a safe or sane way to go? Any ideas?

Richard

 

[jhoughton]

Once you start adding freon the compressor will run longer. Once the compressor is not cycling you should be able to charge properly.

Jim

 

[ralee]

Ah yes, the correct amount of R134A does wonders! 30-32 inches at 65* F. and all is well. Temp measured at the center vent now is 52*.

Thanks to all for the timely advice,

Richard

 

[DieselDoghouse]

Sounds like your set. Don't add too much refrig - this will raise both the on/off pressures and result in the compressor cycling on long enough to ice up the evaporator in the dash - nasty stuff!! (and as it starts to ice airflow will drop accelerating the process).