vanster

Yet another trip to LA and back and my AC still won't cool.
I put two cans of R-12 into the system. The AC light on the center console lights up when depressed , blower works, heater works.
I can't really tell if the compressor is engaging or not. I don't feel a load from the engine when I turn on the AC.
How do you tell if the comp is working or not and how often do they fail? Can they be rebuilt? Seems like a nasty job removing all the hoses.
I know I should have evac the system before putting more R 12 into it but I thought that something would be better than nothing and I don't have all the required tools.
v

John Speake

With the engine stopped, switch on ignition and press/release the aircon button. If there is sufficient gas pressure then you should clearly hear a load click at the front of the engine as the clutch engages.

A final check would be turn the inner part of the clutch, it will be locked to the belt pulley if the clutch is pulling in, and free to turn when disengaged.

StratfordShark

You can make absolutely certain with visual check. With engine idling and AC switch off, stand at front and aim torch (sorry, flashlight!) at the AC compressor pulley on low right side. Have helper push in AC switch, and if compressor engages and turns it will be obvious that the hitherto stationary compressor is now spinning. If not you need to trace compressor 12V supply back from compressor through to switch side of freeze switch (under plastic cowl in front if windshield)

dr bob

If you forego the evacuation part of the charging process, you are doomed to vent temps no colder than the mid fifty degree range. On a cool day. Plus there's no way to get oil into the system unless you evacuate it first; the oil charge is sucked into the system by vacuum from your measuring cup.

For the compressor not turning, the power comes through the AC control switch to the control head, through the compressor clutch relay in the control head, to the CE panel, out to the freeze switch under the plastic shield at the base of the windshield, hen CE panel, through the pressure safety switch, on to the fourteen-pin engine harness connector, through the front of engine harness to a spade connector by the oil dipstick tube, where the pigtail for the compressor clutch coil plugs in.

There are several good write ups on diagnosing and replacing the relay in the control head.

How did you decide how much freon to put in? For a completely empty system, two 12oz cans isn't enough. Good thing you didn't waste more though if the system was holding a lot of air.

Ducman82

i was just playing with this today check my fan set up. low pressure switch stopped the signal to the compressor. 10 bucks thats what your problem is. get a test light and check for voltage at the clutch wire, then check on both sides of the pressure switch infront of the condenser.

Alan

Which would most likely indicate an insufficient charge or a very significant leak (broken pressure switches are relatively rare). You pretty much have to have at least a small leak to have lost enough Freon to need to recharge...

Measuring system pressures is required, significant leak of refrigerant out likely means (wet) air in too... Time for some level of professional help - seems you at least need to find a leak.

Alan

Ducman82

oh ya, its all gone. one of the connection at the compressor came loose after i got home from sharktober. i was using the fan to test for noise in my stereo (which it is causing) so i just had to jump the AC signal to my fan controller since the AC button was not going to do it.

Alan

Actually Jake I was meaning for the OP's case - But yes you are right its pretty universal - if your low pressure switch cuts out then 99% of the time you have a leak.

Putting more in isn't that much of a solution without knowing how much you lost or where its leaking from & how fast. It's often about as effective as just dumping the whole can contents to atmosphere...

Alan

OTR18WHEELER

I'm not an expert, just think my experience may be relevant. The summer of '12 I had a mechanic diagnose my A/C, as it was not cooling very well. He used dye, and found no leaks, he used a "sniffer", and found the leak was from behind the compressor pulley, but minimal. Fast forward to today, the A/C still cools better than in 2012, but is in need of a recharge. Moral of the story, find the leak before you spend tons of $$ on parts.

j.kenzie@sbcglobal.net

Agree with much of above.
Leaks can be big or small. I understand that all R12 systems have slow, small leaks, and if your system has gradually lost performance, it may be justified to try topping up the system. However, it never hurts to know where and how large the leak is. The repair for leaks is always replacement or rebuild of faulty components. Never consider sealant products.
You should try to get at least a low side pressure measurement to see where you stand. High side too would be better.
Good luck,
Dave

Jetdriver69

My 82 had a small refrigerant leak that turned out to be the expansion valve.

It was real tough to find the leak without a proper evacuation and recharge with UV dye.

Drove the car for a week and there was plenty of dye surrounding the cap on the EV.

Thank goodness it wasn't the evaporator!