crg53

I had my air con system evacuated and removed the compressor for new ignition wire install; put everything back together, but the air con has not been recharged. Started the car up and hit the air con botton on the ccu, light comes on but the electric clutch does not engauge; checked the plug with a light, no power to the plug.
My question is, is that a condition of the system not being charged or is there another problem.

tbennett017

Isn't there a pressure switch exactly for that purpose? IIRC, mine had a problem with that switch and once fixed the AirCon was fine. I think it's doing its designed purpose for you.

crg53

You are right, there is a switch under the hood (trunk) just not sure if that's what it's for.

Steven C.

There is a low pressure switch on the system that will prevent the compressor running until you get some freon in it. Usually the first can will get it going.

crg53

Thanks guys, I have no experience with air con, but is it possible for me to charge it myself; I have seen cans at the autostore for that purpose, but not sure how to proceede.

Steven C.

Since you had the system apart it will need a new dryer and a vacuum pulled on it. If it was apart very long you may want to replace the expansion valve just to be sure it will work when re-started. This is a job for a person with the experience and tools for the job.

tbennett017

I concur. For some reason AirCon is best left to the dudes with the right toys. I hate to admit it.

springer3

The pressure switch will also prevent the compressor from running on a cold day. In BC, it might still be cold enough.

darth

Dear crg53

Poor Man's Method
To renew the dryer preheat oven to 200 degrees F, bake for about an hour (i.e. all you're doing is removing the moisture from the dessicant inside the canister and saves you a couple hundred bucks for a new drier) just before you are about to attach it and recharge the system with an R34 kit from your local Princess Auto- about $50.00 on sale. You can evacuate the system or do it yourself with a $20.00 vacume pump which are readily available on EBay. I use my air compressor's input port. Add the R34 until you have optimal vent temperature or the specified amount required. It's nice to have guages but not necessary. I've seen some R34 kits with cheapo guages included in.

Or you can have an AC shop do it.

Bill

crg53

Darth, thanks for the info, I think I will take it to a shop and let them do it, just out of curiosity, where is the the dryer located?

Springer, the car is in a heated garage 68F, outside temp 56F, would it not work under those conditions?

darth

Dear crg53

Behind the drivers side front rear inner fender.

Bill

springer3

Too close to call. My 300 E would shut off the compressor in the low 60s °F. I recall problems demisting the windshield on cool rainy days in the Summer because the AC compressor would not run.

I have never tried the low temperature cut-off on the 964, but it should be similar. If the system is evacuated, it can be charged by weight. If charged by pressure and temperature readings, that should be done on a warm day when the AC has some work to do.

It is OK to jumper out the switch to get the compressor running long enough to charge the system. That will do no harm as long as you are adding refrigerant on the suction side of the compressor.

springer3

The poor man will get even poorer if the compressor is damaged. A hard vacuum for 30 minutes or more is recommended to pull the residual moisture out of the system. Also, if the system has been open, it is a good idea to flush out the oil along with any contaminants. Starting with an empty/clean system, it is easy to add the correct oil charge along with the refrigerant charge.

Steven C.

Do not jumper around the low pressure switch. Without a vacuum pulled you will never get enough freon in it to cool anyway and you risk the compressor in the process. 134 systems are very finicky on amount of refrigerant and the pressures. Small changes affect cooling temp a lot. And without a new dryer the system is going to get corroded too.

crg53

I don't know if this makes any difference, but as soon as I opened up the system I immediately plugged the hoses on both ends and plugged the 2 holes in the compressor; the system was unplugged for about 2 weeks.
I checked with local supplier, can get a new dryer for $78.00.