Automotive Air Conditioning Information Forum

And the hits just keep on coming....
I took the car in and they did their thing with the AC, but the compressor will not kick on. Where would be my first place to check why?

"they did their thing"

What exactly does that mean?
were they able to install a full charge?
Do you have a blown fuse?
Is there a wire loose or off someplace?

They recovered refrigerant and did a leak down test, added dye and some refrigerant. Could not get compressor to run.

I will check fuses. How do I rule out problems with the compressor?

I'll have to go back and re-read this entire rather lengthy thread to refresh my memory about what was done to date, and then I'll post my thoughts.

Thanks, John

"added some refrigerant"

If the full amount is not added chances are good the comp will not run.

If they have an RRR machine they should be able to install the correct factory amount of charge. Was this an actual MACS certified shop, or a brake shop (or the like) advertising that they do AC

My FSM for the 86 Corvette lists 2 3/4 lb R-12 refrigerent (44 oz)
80 percent of that charge for R-134a would be 35.2 oz
My AC guy tells me they put in a charge of 1.8 lbs. He states that this is what his chart shows. I know that is wrong. I ask him if that is enough of a charge to get the compressor to run and he says it is more than enough.

JohnHere in an earler post states:
The original information that I have for your car specifies 52 ounces net weight of R-12 and 7 fluid ounces of Mineral Oil. Of course, now we're converting to a somewhat reduced amount of R-134a, which can be addressed later. But the 7 ounces of oil (be it Mineral or PAG) is still a valid spec for your system. So you'll need to add 4 more ounces of oil someplace—PAG oil this time—either to your new R-4 compressor (if it will take all 7 ounces), or to make the process easier, introduce 4 more ounces into one of the service ports using the proper tool. The latter method will eliminate having to disassemble anything, which you don't want to do at this point.

After adding the oil, you can proceed to weigh-in the refrigerant—beginning at about 80-percent of the R-12 amount—into the well-held vacuum...if you can do so at your locale's ambient temperature. If not, add maybe a 20-percent charge and wait until Spring for the rest.

I don't know where he finds that info but I would like to know where.

This is what one member of the Corvette community suggests as far as checking compressor:

Put some gauges on and jumper out the compressor controls(should only have to do the low line cycle switch) and see what the pressures do. If the pressures seem adequate according to a 134A chart, then you have to troubleshoot the control system.

If I put a pair of jumper wires from the battery directly to the clutch coil terminals on the compressor,will this confirm the clutch is working anyway?
I have the ACDELCO 1521638 R4 compressor with the two pin coil connectors. Does the polarity matter connecting these jumper wires. On the compressor, there is a triangle shaped stamp next to one of the terminals on the compressor. Would that be ground?