Every since I bought the truck a couple months ago, the a/c clutch keeps cycling on and off in any of the "right" heater modes. It does cycle a little less when it's on MAX a/c though. Standard climate controls btw.
Doesn't blow out particularly cold air, but I put a gauge on the low side, and if the a/c is on normal, or on defrost, when it cylces is goes from 40-25psi rapidly, so I would imagine it's got enough coolant. Then when I out the A/C on max, it stays at around 43psi.
This is testing it inside my work (70* or so). The cycling on/off would happen even at high temperatures when it was still summer out.

So my main questions -
the cycle switch: if it just has a postive and negative, could I just "hook up" another wire to the positive side and check the pressure? If it works more like the low pressure switch, can I just jump it? Or is there any better way to test it.

I suppose I could just go and get a switch, but figure I mine as well ask first before I go through the "trouble".

 

The cycling switch is the low pressure switch. Judging by your pressures, I'd say it's working normally, they're usually designed to disengage the compressor clutch at around 20-25 psi. You can jump the two terminals of the switch and force the compressor to stay on, but of course this isn't something to do for a long time. If I were working on your truck, the next step I'd take is to recover and weigh the refrigerant to see if the system is low. If it cycled rapidly during the summer heat (is that relative in Alaska? lol), it may be low on refrigerant.

 

It still cycles on/off when I jump the low pressure switch. I thought the clutch cycle switch was on the accumulator/dryer?
I assume it wouldn't hurt anything to leave the pressure switch disconnected for a little while, that way I can drive around with the defroster on and not worry/get annoyed by the clutch cycling on and off?

Hey it gets hot here lol. Yea did same thing when it was hotter out.

 

New info - jumped the switch on the accumulator. Clutch stayed on, and pressure on low side was around 15psi

 

What kinda temps are you getting at the vents? The switch on the accumulator is the low pressure switch, sometimes called a clutch cycling switch. The switch by the high side service port is the high pressure cutout switch.

 

Shoot, I should have known that. Getting confused looking at old posts.
I don't have any good way to measure the temperatures at the vents, but it normally feels almost the same (if not) as on Max A/C as it does on PANEL.

Thinking about it, I would imagine it's low since when it kicks on, it goes to 20-25, and my guess is it would go lower than that (to the 15psi I got when jumping the switch) if it didn't disengage, building the pressure back up.

Edit: forgot I had a slightly better gauge than what I was using, and it got like 5psi.
Now I am concerned there might be a big leak somewhere.
It's not so much that I "need" a/c here, but it gets annoying having the clutch kick on and off. So, either way I guess that problem will get fixed. No leak, fill with refrigerant, big leak, "deactivate" a/c since for 9 months I don't need it anyway

 

Tip: Compressor clutch short-cycling is almost always due to an insufficent refrigerant charge.

A low side pressure guage is not adequate for troubleshooting. You really need a set that also measures the high side.

I'd suspect your "new" guage is defective.

Steve

 

Steve hit it on the head. If you want to trouble shoot A/C problems yourself invest in a set of gauges ( high and low side ) and a thermometer. Can't begin to guess the number of times people have come to me with a "warm'" air problem and you put a thermometer in the vent and its blowing 36 degree air. In a perfect world a system will never leak. That being said they do sometimes weep a little. The fact that you only use A/C a couple months a year only aggravates the leak problem. The A/C running also circulates oil in the system. This keeps the seals and O rings at the fittings lubed. Inactivity is the worst thing for mechanical systems.

 

Thanks for all the help guys. This coming Wednesday I'm just gonna get more refrigerant and put it in, and see what happens. Probably get 1 can with oil in it as well.

I had always thought that there would always be some loss, but when I was fixing the a/c on my Taurus, people were saying it should never lose any really.
Granted I already knew it was because one of the a/c lines got cut (rubber).