HELP!! Strange cycling switch problem.

[meck1]

When I use a jumper wire across the clutch cycling switch, I get good pressure readings and cold air. But when the cycling switch is attached, the compressor is kicking off at too high a pressure, the cycling rate is fast, and the air never gets very cold. I changed switches, but it is still kicking off, like before, at around 35 pounds. (The manual says it should be in the twenties). Can somebody give me a hint of what is going on? By the way, this only started this Spring. And I have evacuated the system, drawn a vacuum, etc. and recharged. Nothing seems to make a difference.

Any advice will be appreciated.

 

[fixxxer]

I referenced my Ford TSP Service manual and the normal duty cycle (1 full on-time/off-time cycle) could be anywhere from 15 sec to 30 sec. with the ambient air temp being 85-90 degrees f. Low-side pressure should be from 20 to 50 psi, high side, 180 to 270 psi @ 85 degrees.
Is yours cycling faster than that? what is the on-cycle time? the off-time?

 

[meck1]

Today, with ambient temperature of 85, holding at 1500 rpm, the on time was 4 seconds and the off time was four seconds. The compressor is kicking off at 35 lbs (low side) and on at 47 lbs (low side). The Ford manual says that the switch is preset to kick off at 27 lbs, but it is kicking off well before that.

If I unplug the cycling switch and put a jumper across the connector to force the compressor to stay on, the pressure settles down to 25 low and 220 high, and the vent output is down in the forty degree range. As I said in the original post, I replaced the cycling switch, and doing so made no difference.

If you've got any idea what's going on here, I would certainly like to hear it. And many thanks.

 

[96eb96]

try the forum on www.ackits.com, hate to send you there from here but there are a/c pros who can help.

 

[meck1]

Thanks for the tip. I'll try the website, because this problem has really got me stumped.