I've searched the forums and can't find what the normal pressures should be for the high and low sides. What pressure should the cycling switch turn the compressor on and off at?

 

The switch closes at 45 psi ascending and opens at 22 psi descending. (Give or take a pound or two).

Actual pressure depend on many variables.

Typically, you'll see low side between 25-35 and the high side should be around 2.2X ambient temp.

Again, those are VERY general readings.

Steve

 

Perfect, just what I was looking for
I'll have to hook the gauges up tomorrow and check the pressures.

 

Verify you perform proper setup per the service manual prior to testing.

If you do post pressures, include ambient temp and confirmation of proper setup.

Steve

 

I don't have a service manual so I just "winged it" based on the 2.2x rule. I would like to see what the official charging procedure is to see how far off I am. Final pressures with the A/C on normal, fan on high for max pressure on low side. Engine idling outside temp 97. High side 250, low side 40. Revving up the engine drops both pressures, I would have though revving up the engine would have INCREASED the high side, but it went down instead.

Hitting the condenser with some 75 degree water dropped the high side pressure to 150 and at idle. When the A/C fan was on high the compressor continues to run. When the A/C fan was on low the compressor cycle switch would kick the compressor off when cooling the condenser w/water.

Before testing the compressor was cycling at idle bringing pressure down to 25 before the cycling switch kicked the compressor off. I'm probably overcharged a little bit but since I had to put some freon in last year to get the A/C to cool well, apparently I have a small leak somewhere.

 

54- To properly check pressure you really should have a large fan (like a Patton fan) a few feet in front of the radiator, on high. Especially on a day that hot. Also run the rpm up to about 1700- 1800Rpm. Idle on a hot day with no air movement your going to run pretty high pressures and not going to get an accurate reading. Your high is going to come down when you rev because your getting the air movement over the condenser. I have seen the high side go to 350- 375 when the elec. fans weren't working on a Honda Accord once (time to shut it down) and it wasn't that hot either (maybe 75 degrees) When I replaced the blown fuse they returned to normal. I also had a 325 BMW do the same thing and it has an engine fan and aux. elec. fan in front of the radiator. The resistor on the elec. fan was cracked in the accident and didn't let the elec. fan come on. When the resistor (I guess that's what it is) was replaced -normal pressures. I didn't realize it would have that much affect with the engine fan (multi-blade) still working but it sure did.