1990 C-4 - 60K miles: Always had COLD Air. Went to Joplin corvette weekend last month, 100 mile drive. Air seemed fine. At home, put car in garage and it sat until this past saturday. Drove 30 miles to a local show. Had exactly "NO" cold air. Had a friend check freon in it today and it was a bit low but still had 80# pressure. Started to pump some freon into the system but the ac would not engage the pump. Shut off engine, began checking electric wires and neither of the switches had current. Is there an "in line" fuse as well as one in the panel or does anyone have any ideas to help me out? Appreciate any constructive comments. Thanks, Jack

 

Orifice filter might be clogged. $2part; $75 job.

This will give a false low pressure reading, and shut down power to the compressor. Check your low pressure reading static (motor off), and check it again motor on A/C max. If static pressure is high, and it then goes to 0 (very low), the flow MIGHT be impeded by the clogged filter.

 

Thanks and happy birthday. Busy today but will get on this over the weekend. J

 

There is a compressor relay and I will have to check my wiring diagrams to see if the cycling switch on the accumulator has voltage or is a ground path. I will try and get back to you. Does your car have ATC (Automatic Temp Control)?I will post diagrams as soon as I can.

 

Hi Mech, Thanks for the lookin and info. The 90 haswhat is called the ECC (electronic climate control). I think it is the same as you are referring to. You can set the desired temp by digital readout, choose "auto" andin a few secondsitswitches back to showing the outside temp. T J says the filter can also shut down the power. Any info you find will be appreciated. I hate to pull that compressor and tear into it before I try some other things. The "No Power" at the two inline switches is giving me first concern but it still could be the filter. J

 

Orifice tube stopped up will not shut down power, unless the cycling pressure goes to low. Try bypassing cycling switch on drier to see if that works.

 

Thanks again.Will be super busy this week but willtry your suggestion, about the bypass, next week. Little things like this bother the heck out of me, especially when I can't get right to them. Next week I'm going to concentrate stricktly on this problem. Will post the results. j

 

The bypass trick with a paper clip takes about 2 minutes, if you take your time. Do it quick, and you might be able to kill 20 seconds to test it.

If it does jump, then check the static pressure (motor off), and again with the compressor jumped, motor on. If the filter is clogged enough, the pressure at the gauge will go to near 0. That will make the compressor shut down.

You can test it in 4 or 5 minutes, and get most everything figured out, unless you're SUPER busy...

 

Here is an abbreviated wiring diagram. The switches have power through them.
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Can't thank you enough. Really appreciate you both sticking with me here. Certain the wire diagrams will be of use. I printed them for reference. Craft weekend here in Arkansas and very busy now but will start on this project after cleanup on Tuesday. Had another question. Is it possible the Heater will not work either until I fix the AC?? The blower fans do still run. Any thoughts here? Just curious. Jack