The wife and I were on our way to Nashville GG today and about an hour out, the AC quit. I had tried to add some refrigerant last weekend but the low side gauge never got above 15 psi and it didn't seem to want to take any more. It was cooling really well until it just stopped cooling. Fan still blows, etc. After I got to Nashville, I bought a fresh can of R134 and tried to add some to the system but the clutch didn't pull in. With the system at equilibrium, it probably has 100 psi on the low side gauge. That seems to be enough that it should cycle on, shouldn't it? If that is, perhaps I have a blown fuse for the clutch. This car is new to me and it has an upholstered panel that covers the underneath side of the dash. Therefore, checking fuses, wires etc. is a PITA. I do have a multi meter with me if there are some quick under the hood things I can check. Any direction you can give me will be greatly appreciated. It's pretty hot here and my wife don't like to sweat.
You already figured it out, you need to see why the clutch doesn't engage. could be a wiring problem or blown fuse, etc.
WHat he said^^^^ I might also add, you may want to add the die to the system, and look for leaks, its sealed and should hold a charge permenantly... The system should be vacuumed down and held, for 15 min to remove any moisture other wise it will contaminate the inside and corrode. this will caus eproblems as well..
if you dont have a leak and the system was wired correctly with the appropriate limit switches in it you could have over pressurized the system where the system is attempting to pump liquid....AKA not good.....in a case such as that the limit switches prevent the compressor from cycling on to alleviate damage to the compressor.... I wouldnt recommend just slamming refrigerant in the system until you actually figure out whats wrong with it. Additionally, I put UV die in all of my cars at some point or another, now days you can buy a can of pressurized UV die in which you dont have to pull the system down to inject it into the system....the above poster is right, if you open the system up briefly I would say 15 min in a vac*** cycle is enough, however if the system is open for longer, especially in humidity I would pull the system into a vac*** for a minimum of an hour, depending on the weather conditions and if the system was physically open (unconnected hose etc) I would pull it down for even longer. At the end of the day you need to start easy and go hard....IE check your fuses and/or jumper the clutch out.
That 15 psi low side pressure does not sound right, what was the high side pressure at the time? Showing 100 psi static with the system equalized I would tend to think you might be over charged. This suggestion is pretty shade tree, but if it were me out on the road and the wife was not happy, I would probably jump a temp. hot wire right from the + side of the battery to the plug on the clutch and see if it kicked in and made cold air. If it does use your own judgement from there. If it cools and you have gauges on it watch the high side pressure, if it starts going north of 300 psi, then bleed out some of the gas.
Well, after talking to the Vintage Air guys and doing a little checking, I think I have a bad thermostat. The power for the clutch comes from the thermostat and goes through the binary switch. I have evaporator fan but no juice to the binary switch on either side. Guess I'll have to ride home hot. Thanks for your help.
Also just for kicks to get you home, try using a screwdriver handle or piece of wood and tapping the front of the compressor clutch with the ac on and clutch spinning. Last year had mine go out on a hot trip home. Tapped clutch and it kicked on. Got home and reshimmed the clutch and it's been working fine
After a little more thought, here is what I did. I have a hot wire from the alternator going to the binary switch. I also have a 10 amp fuse in that line. When I hook it up, the AC works. My plan is to connect it right before I get on the interstate and let it run. I have a master kill switch which I will disconnect each time I stop. Will this work and get me home? I know it won't cycle the compressor on and off but I have the binary switch to protect me from over or under pressure. Since its hot as heck, almost 90, the compressor likely wouldn't cycle off much anyway. Right? If I'm wrong, tell me before I cause more extensive and expensive damage. Thanks!
The binary switch should protect against over pressurizing. Also make sure your fan is pulling air through the condensor (i suppose its stacked with the radiator on your car) You sure your feet didn't snag a wire under the dash disconnecting the Evaporator? Oh. Just read about the upholstered panel. Too hard to pull that out and look?
You can hot wire it like you said,you may not get the compressor to cycle to keep the evaporator at temp above freezeover, you will most likely get the evap to freeze over and loose airflow, then you will have to unpower to thaw to get airflow back, depending on humidity in can be a pain in the but. But a cheap toggle switch and when you lose airflow turnoff till it comes back and then you can switch back on.
Before you do anything to the system just try bleeding of some of the pressure, you probably have it over charged and the high pressure switch will not let the clutch engage. If you jump wire it you will damage the system, probably blow a hose or the condenser. It will only cost you a can of 134a to try it.
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