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Air Conditioner Failure

Dan Hunter

Dan Hunter

Truck Terrorist
Messages
441
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5
Location
Enid, OK
It's been so long since she's given me a problem.

My compressor clutch isn't engaging. I checked the fuse and it's good. My first guess is that it needs serviced and a low pressure state is preventing engagement. I know within about 1 minute when it failed and it was working fine and quietly up to that point.

Any suggestions?
 
Dan Hunter said:
It's been so long since she's given me a problem.

My compressor clutch isn't engaging. I checked the fuse and it's good. My first guess is that it needs serviced and a low pressure state is preventing engagement. I know within about 1 minute when it failed and it was working fine and quietly up to that point.

Any suggestions?
Click to expand...


I had this happen and at the same time I notice that when the fan was turned on it would immediately blow out the floor vents only (no defrost) It was the heater control unit in the dash.
 
Dan Hunter said:
It's been so long since she's given me a problem.

My compressor clutch isn't engaging. I checked the fuse and it's good. My first guess is that it needs serviced and a low pressure state is preventing engagement. I know within about 1 minute when it failed and it was working fine and quietly up to that point.

Any suggestions?
Click to expand...

Dan, mine did the same thing here a while back. Try sticking a paperclip into the pressure switch plug and see if that gets the clutch to work. If it does, then the system likely needs a little shot to get it back up and running.

Just go buy the 134A stuff and do it, -piece of cake.
 
FWIW, if you decide to add freon yourself be sure to get a gauge. I used to do R12 by adding until the compressor locked and let enough out until it worked, no problem. With R134 the pump will not usually lock if you get too much in, it just destroy itself. You can overfill the system and still not have cold air.
 
JiFaire said:
LOL...move North, Dan. We haven't really needed AC yet. :D
Click to expand...

If one subscribes to global warming, you will.

The pressure switch plug...is that the one in the back that is barrel shaped?

I have competent assistance at the auto hobby shop that can charge the system if that's all it needs.

I've finally finished the relays on the headlights on the Deuce in my avatar - shameful, isn't it - and may just ride it for a while and offer the truck threats of abandonment to make it behave.
 
94..Make sure it's r134 for starters. I think there were. Preachermic, easy there. Filling the system until the compressor locks up=bad idea. Sure way to blow something. The "right way" to do it on a GM system is to evac the system and recharge exact measured amount. No more, No less. For us backyarders without a charging station, the poor mns way. Close all windows put a/c on max. Put a thermomter in the center duct will all others closed. SLOWLY fill system 1 can at a time and wait 10 mins or so between cans until you achieve39-45 degrees 39 being ideal and rarely seen on a GM.. If you have the system open then just put measured amout back in. The procedure I described is if the system is still sealed but not evaced. DO NOT OVERCHARGE. Keep can upright. It's tempting to turn it upside down to hurry up but bad idea. That "sometimes" can also cause damage.
 
Brooklyn Tow said:
It never goes in upright.....always need to turn it upside down.
Click to expand...

Yes it does. it takes time. read the can. Say "ONly use this side up"
By turning upside down you are putting pure liquid in it. That can lock the compressor . Most of the time it will work anyway but I ran into a system where the compressor was locked up and the guy had done that. I had to flush the whole system , empty the compressor and refill and recharge. it worked fine after that. It was on an old Dodge motorhome.
The cans are labeled for a reason.
 
You can temporarily jump that with a paper clip while charging. It will make it go alot faster. As Brooklyn said it is hard to get it in waiting on it to cycle when low.
 
So you jumper the low side switch to keep it from dropping the compressor at 20psi ? I can get mine to pump until low side hits 20 then it kicks off. High side around 120-150 depending on outside temp. It'll only pump for about 2-5 seconds and kick off. System off pressure is around 70/70 at about 80 outside temp.

Thx, Mike
 
OregonHorseTug said:
So you jumper the low side switch to keep it from dropping the compressor at 20psi ? I can get mine to pump until low side hits 20 then it kicks off. High side around 120-150 depending on outside temp. It'll only pump for about 2-5 seconds and kick off. System off pressure is around 70/70 at about 80 outside temp.
Click to expand...

These numbers seem right compressor should kick off around 20 - 25 psi and back on around 45 - 50 psi. Your balanced pressure is right at 70. your high side pressure seems a little low should be around 180 psi. you might put a little freon in but not much. put the liquid in the low side not the gas.
 
The jumper is just for charging. Don't leave it jumped or the system won't cycle. the compressor will just keep chillin away until the system freezes and explodes. Not pretty.
 
Acesneights1 said:
Yes it does. it takes time. read the can. Say "ONly use this side up"
By turning upside down you are putting pure liquid in it. That can lock the compressor . Most of the time it will work anyway but I ran into a system where the compressor was locked up and the guy had done that. I had to flush the whole system , empty the compressor and refill and recharge. it worked fine after that. It was on an old Dodge motorhome.
The cans are labeled for a reason.
Click to expand...

Actually, the can says to shake/rotate between 12 and 3 o'clock position (at least the cans I use do).....which, if your gauges have a sight glass you can clearly see it lets liquid in - never been a problem for me. I would not just turn the can upside down though. Doing it the way that's suggested on the can gets the charge in pretty quick and kinda 'controls' the rate of liquid by not allowing too much.

If you absolutely HAVE to hold the can upright, at least fire up a coleman stove or if your gas grill has a side burner, put a pot of water on it and get it nice and hot, open the valve on the refrigerant and drop it in the hot water. I say 'drop' it in...more like ease it in and watch the low side pressure if your using gauges - it can slam the needle against the stop somewhere around 125 psi. It'll be the fastest you've ever seen an upright(gas only) charge.

My uncle used to have a service station back when r12 cost under $1.00 a can. Nobody fixed their a/c leaks - at that price they could afford to get it charged up once a month if necessary. As summer started and the temps creeped up into the 90's, I can remember lines 20 cars long waiting to get charged up. He'd have a mechanic standing there outside the service bay with a fish cooker boiling water....sometimes for hours. He'd drop in a can or two while my uncle collected the cash from the driver.

It was basically a drive through A/C service - customer never got out of the vehicle. :D
 
If it is a 94 and you have never changed it, it probably needs a new compressor and some renewal. I bite the bullet and changed it last year after 2 years of recharging it. With some of the heat lately, it was a good investment.
 
If you have a gauge harness you can charge until the pressure fall into line with specs and the system will cool sweet.

If your system abruptly went warm and stopped cooling, you likely have a failed hose, Oring or other sealing device.

Failed evaporator or condenser.

A good electronic sniffer is the only way to find the leak.

The hoses are known to fail at the crimp area where they meet the aluminum tubing.

Other areas of failure can be the low pressure switch itself (leak through) and or the High side cutout switch on the back side of the compressor.

Put enough 134 in to get some pressure up and run the sniffer all around.

Even the charging ports can leak (check valves will fail)

Evacuate with a HVAC vacuum pump to 29-30 "HG for 30 minutes to remove all traces of moisture and then charge through the low side port.

Never open the high side valve while running, lest thee be found wearing parts of the 134 can on thy person :eek:

If the can gets cold in the upright position, resit the temptation to invert but instead, simply warm the can in a pan of warm tap water. This will make life better.

Doing the charge without gauges is not impossible but one needs to observe the air temp at the vents and how the clutch is cycling.

I use a dual gauge charging harness and a large pail of 134 (looks like a barbeque propane bottle)

The old days of R12 were sweet. Less issues with the stuff.

There is a Product that will replace 12 and 134 called envirosafe. Great stuff and it take a lot less of it to get things working right.

Has a PINE scent so you can tell if the evap has a leak inside the rig.

To do a 12 system you need to replace the charge ports with the 134 style(screw on retro kit)

The envirosafe will work with any of the different oils too and does not scew up the seals in the 12 systems like 134 will.


Check yopu system to see where the juice went.

A major leak may also show signs of oil around the area too.

Best

MGW
 
On my rig, the check valve on the high side quick connect leaks when the plastic cap is off. It doesn't leak down when the cap is on as the system maintains pressure for months and I have had the truck for over two years now and never seen it below a balance pressure of 70 (warm day). Can I change or fix just that check valve without replacing the whole hose assembly? Is it like a shrader valve on the old R12 systems?
 
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