Yes, unfortunately I did check the voltage at the compressor and have 12V. That is the puzzle. If there is 12V at the compressor why isn't it coming on? As I mentioned, I hooked the voltmeter to the green and black wires at the compressor and could see the needle move to 12V when I turned the heater control switch on the shifter console back and forth to A/C. But I can take a spare battery, hook two leads directly from it to the compressor and it will come on.

All I can think of is that, even though I have 12V at the compressor, it is not enough amperage to cause the clutch to engage. I am not much of an electrician so I could be way off on this. Unfortunately, my VOM only measures milliamps.

Maybe someone could give some info on basic electicity for this one.

Thanks for all your responses.
Mickey

Well, if nobody here comes up with an answer, go surfing, search "Corvette Air Conditioning", you will find parts, suppliers,and FORUMS,if I remember right it didn't take to long to find the forum,damit, I didn't save the page, good luck.

If you are reading 12 volts at the compressor with the engine running, it's too low. It should be battery voltage. With the age of our cars, look for at least .5 volts of battery voltage. Example, 13.8 batt volt. look for a minimum of 13.3 at the compressor.

If you have less than that, you have high resistance and are restricting the amperage. This extra resistance could be in just one place, or a combination of several places. You have a volt meter so you can find it using a voltage drop test.

Check each switch with a voltage drop test. Place the postive lead of the meter on the powered side of the switch. Place the negative lead on the switched side of the switch. Activate the circuit (turn it on) The volt meter should read 0 volts. If there is a reading, you have a voltage drop of whatever the reading is. This drop is due to resistance in the switch. That cuts amperage. You should not read more than a .3 volt drop, across any one switch, and ideally less than .2 volts. You want less than .5 volts for all of them. So if each of 3 switches reads .2, that's a total of .6, and it's too much.

This can be contacts in the switch, connectors, or even corroded wires. Any electrical component, wire, connection, etc, can be checked this way. It's much more accurate than an ohm check. It testing a live loaded circuit instead of a dead one.

Let us know what you find.

i would also recommend buying an inductive ammeter..

they come in very handy.. you can check what it pulls from a battery.. then test what it pulls when when powered by the car..

also use this to test current through various switches..

this could be something as simple as a weak alternator.. have you had it tested ??

|UPDATED|8/14/2004 12:38:56 AM (AZT)|/UPDATED|