72chevelle6.0

iTrader: (22)

The ac that we installed in the 69 chevy c10 we are working on was working good.. we had used it about 10 hours or so.. then it just started to blow hot air.. so I called classic auto air about it they told the to check the pressers well the low was pulling a vaccum so they told us to check for blockages.

We took everthing apart and we could blow air through it. So called classic back they said it could be the expanstion valve so they sent a new one intalled it pulled the vaccum and recharged.. it worked on with the 1 can of 134A. (about 60 out the vents on a 90* day) about 20 on the low and 150 on the high. but when we trun the a/c off and try again it will pull a vaccum on the low side again.. classic told us to "tap" on the expantion valve. this will get it to open but next time you try to use the you have to tap the valve again.

could we have gotten 2 bad valves?

also we noticed that the valve was icing up.. we are using the 01 truck a/c compressor could it be too big?

Clyde65

I have old air products unit in my 65 and the 02 Compressor from my 4.8 and it blow ice at me and doesnt freeze up so far, I only drive about 10 miles at a time but it is sometimes stop and go.

91sbcamaro

iTrader: (3)

Is your compressor cycling like normal or is it always staying on? I could see it freezing up if the compressor is always on, I think most compressors have a cylce of turning on and off. Most of the time you can hear the clutch engage/disengage.

Clyde65

It seems to be cycling normally, I havent noticed anything out of the ordinary, I just had it at the service place to check the freon and an oil change and my extremely picky mechanic friend didnt say anything and believe me he would have.

Old Geezer

iTrader: (3)

V/A has a warning about that problem. Says to move the temp lever toward the warm side until the ice melts, and the system returns to normal operation.

G-Body

iTrader: (4)

You need more freon. 20 PSI on the low side is too low, its icing up. the low side should be 24-46 psi (lower pressure = colder air, but increases the risk of freezing the expansion valve )

72chevelle6.0

iTrader: (22)

The compressor does not cycle on and off..

I have two cans of 134A in the system now. the high reads in the 180 and the low is still about 20 -25 sometimes. if I put much more then that the a/c compressor has a hard time turning on.. the motor will try to stall.. the guy at classic said that 2 cans should be about right.

A-Body

The ideal pressures of the system are 15-28 on the low side and 180-220 on the high side. If the system is not within this range with 1.5lbs of R-134a add more freon in .25LB increments. If the high side gets high, and the low side stays low you have a condenser-cooling problem. Do your electric fans turn on with the ac..

72chevelle6.0

iTrader: (22)

yes the fans do turn on with the a/c compressor.

Palomba

iTrader: (1)

The expansion valves can and will freeze up, and take a while to defrost themselves and return to normal operation if your pressures are not right, like stated above.

LS1GMCTruck

iTrader: (2)

If a system is overcharged(with freon), can this cause the compressor to cycle excessively as well?