Automotive Air Conditioning Information Forum (Archives)

73Wagoneer on Thu August 20, 2015 7:30 PM

Year: 95
Make: Chevy
Model: P30 chasiss
Engine Size: 7.4
Refrigerant Type: R134
Ambient Temp: 95
Pressure Low: 35
Pressure High: 280

This system is on my RV P30 chassis, basically the A/C system is like a Chevy truck or Van

Just bought this RV, and while checking everything out, I noticed that the A/C compressor does not disengage, the pressures stay the same, the vent temps are 50 degrees with outside temp of 95.

Not sure if this is normal

My pressures seem to be fine, it cools down to 50, so is the A/C compressor not disengaging because the high pressure does not go up, I did notice looking at the sight glass on the drier it has a pretty good stream of bubbles.

Just looking for guidance, I am a firm believer if its not broke don't fix it, just not sure about the compressor running all the time, never seen this before.

GM Tech on Thu August 20, 2015 9:40 PM

It won't cycle unless the heat load decreases, as in lowering the blower motor speed, or the ambient temp goes down- 35 psi suction is a good pressure- won't cycle until it goes down to about 22 psi- a 45 degf temp drop is pretty good- considering you are probably on outside air and high blower- try it on low blower inside air- it will be even colder.

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

73Wagoneer on Thu August 20, 2015 9:51 PM

Quote
Originally posted by: GM Tech
It won't cycle unless the heat load decreases, as in lowering the blower motor speed, or the ambient temp goes down- 35 psi suction is a good pressure- won't cycle until it goes down to about 22 psi- a 45 degf temp drop is pretty good- considering you are probably on outside air and high blower- try it on low blower inside air- it will be even colder.

Great, I was doing some more searching, and found out as well if I have it on high, probably wont cycle, thanks for the info about the 22 psi cycle pressure was trying to find that.

It was on recirc (inside air) but its a big space to try to cool

Looks like the system is running as designed. Thanks again.

Edited: Thu August 20, 2015 at 9:52 PM by 73Wagoneer