irwiny

My 66 / 327 NOM has been having problems in the past with the A-6 AC that was re-installed back to factory. Previously the belt installed was the not correct and the pulley was leaking. As a simple fix, I installed a pulley shield, added a bottle of Freon/Max seal and monitored. Added about 12oz last year and no isues.

This past week I installed a correct width and length belt (15575), replaced the fan clutch to a non thermo version and added 12 oz of 134a freon.

Now when I turn on the AC the pressure relief valve sprays out freon when the AC is turn on. This happened three times in a row.

After I cooled the car, I connected my low cost low pressure gauge w/o bottle used to refill the freon and the low pressure was about 125-150 psi with engine off. I felt it was high and lowered it back to green.(55 psi)

Is there a reason why (over charged ) and any suggestions?

Thanks...

Irwin

Chuck Gongloff

Although I know very little.... I have been learning as I have been fooling with the VA system on my old hot rod.

Lots of factors...ambient temperature, humidity (dew point) etc. go in to the mix.

However... seems to me that 55 PSI is awfully high low side pressure.

What does the gauge show with the car running?

domenic tallarita

That can be serious, blowing out of the relief valve, because that's what it is designed to do if it is overcharged. It may be bad, but I doubt it. I test my compressors @ 350 PSI and have never had a valve leak. I believe the blow off is 440 PSI.
I would get a set of gauges and test the high side.

Dom

Powershift

You likely have one of three conditions:

1. Faulty relief valve

2. Plugged or restricted expansion valve (TXV valve)

3. Significantly overcharged system or air in the system.

You need someone with a full manifold gage set to check the system pressures when cold, and then when the engine is running and the compressor is energized. This should tell you about item #1 as the relief valve should not normally blow until 400 psig or so (not certain of exact psig without further checking......but this is a close number).

For item #2: If system is cooling the cabin, the TXV valve may be okay.

For item #3: If system is overcharged, or suspected of being overcharged, you can let some of the refrigerant out of the system and stop when you observe bubbles in the drier sight glass and the discharge pressure gets below 250 psig (or so). Best is to vent the entire charge, pull a vacuum on the system with a vacuum pump to remove any air and moisture and then recharge to about 80-85% of the R12 charge............for R134a the FULL charge should be around 42-44 ounces of refrigerant. There should not be any bubbles in the direr sight glass at this point.

Bubbles in the sight glass can indicate the refrigerant charge is low (if no air is present), or it can indicate air/moisture in the system. You manifold gage readings (both hi and low) and inside cabin cooling will tell you (or a good technician) which one it is.

Larry

EDIT: For a good performing factory system with R134a, the suction pressure (low side) should be around 30-35 psig and the discharge (high side) should be around 200-250 psig during a warm summer day. These are approximate numbers until you tell me the exact air temperature when you took the readings and if you had a large fan blowing fresh air into the grill area.

irwiny

Thanks Dom, I going to take it to AC shop to remove and recharge the system. Also get a spare relief valve. I thinking I did over chargen it. For now I'm not turn on the AC.

Hope all is well in Palm Springs. Spoke to you before on the phone and still impressed with your facebook profile image.