760GLE 1988 Air Conditioning Refurbish

DeRail · Post by **DeRail** » 27 Feb 2009, 10:45

Guys, here's my story. I bought my car (760 B280F) almost a year ago with the A/C not working. Considering last summer was a bear, I'm going to try to get it working before the hot weather hits! I need some advice from the fine folks at MVS

I have no prior knowledge of what was done to the AC system other than this...nor do I know why the belt was disconnected.

The belt that connects the compressor to the crank pulley is missing. However, looking at the belt diagram, there is a tensioner or idler pulley that it runs around that is rusted frozen. I'm guessing the first step would be to get a belt on there with a new tensioner, now what is this tensioner called and can I get it from FCP or ipd? (It's just a pulley with a bolt running through it from what it looks like). When I was just testing, I activated the AC switch on the dash, whilst spinning the compressor by hand, but it seemed the clutch did not engage because the compressor still freely spins. I don't know if this is a valid test, but I'm just putting it out there. There's no sticker on the accumulator that says (134A) so I'm guessing it's still R12. So I don't know if it's more economical to convert to 134a -- also is there a quick way to test the electric fan in the front of the grille?

Any help would be appreciated before the warm weather

Also, someone mentioned that reconnecting the AC on an older car will suck the life out of the engine... it sounded a little farfetched to me, afterall it's only one more belt, but just wanted to see what you guys had to say about it.

Thanks!

Post by **billofdurham** » 27 Feb 2009, 12:51

Any help would be appreciated before the warm weather

Is warm weather scheduled for this year?

Attachment shows the AC compressor and other bits. If it is #7 or #11 you should be able to remove it and get it working again.

760 Compressor.pdf: (317.08 KiB) Downloaded 122 times

To jump test the compressor I run a lead from the battery + and touch it to the + connector on the compressor just long enough to see if it kicks in. On this model the wire to the + connector on the compressor should be black.

also is there a quick way to test the electric fan in the front of the grille?

Again, a jump lead from the battery + to the fan +, on this model it should be a grey/red wire.

If it has been converted to R134a it should have a sticker on but this may have come off over the years. Another way to tell is the service valve.

R134a service valve.pdf: (466.08 KiB) Downloaded 185 times

I have never heard of the AC having a truly adverse effect on the engine of an older car. It will use a little more fuel but a new car has that problem.

Bill.

DeRail · Post by **DeRail** » 27 Feb 2009, 13:14

Hehe, tell me about it, it's been freezing but I think there's a light at the end of the tunnel

It would seem that #7 is the culprit, thank you for the diagram. If I have to make a trip down to the dealer, I'll bring a copy of this with me. From memory, the service port looks like the R12 version

I will try jump starting the compressor and fan and will get back to you. Thank You so much -- The last time I went down to the dealership they could not locate this part, now I know that it's at least in VADIS from what it looks like.

DeRail · Post by **DeRail** » 27 Feb 2009, 15:59

Hey sorry for the double post, but will I be able to test the compressor without attaching the AC belt, can I just spin it to see if the clutch engages, or will I be able to hear it, etc?

Also: this low pressure switch I keep hearing about, is that something that would be in my car or is that only in the later volvos and is it worth trying to jump that over hot wiring the compressor?
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Walked out and took a look at the compressor, there is a square connector that fits into the back of it, with a yellow wire that I believe runs into the accumulator. If I disconnect the square connector, which part of the connector on the compressor should I apply a 12v lead?

Also, called down to the stealership about the idler pulley and they wanted about 100$ for the item. I've inquired at the usual parts houses and am waiting to hear back, but that just seems a little outrageous!

Post by **billofdurham** » 01 Mar 2009, 12:49

For the exceptionally short time of the test you do not need a belt on the compressor. Applying power in a 'flash test' like this shows if the compressor clutch is working.

According to the only wiring diagram I have for this year/model the wire coming out of the compressor is black which becomes green/yellow then green to the pressure sensor which will be on the accumulator. The only other connection shown is direct to earth (ground) which may be achieved through the body of the compressor and not necessarily by a wire. Take the connector off and touch a live to the pin.

Is the idler pulley pure platinum or is it just plated? They probably have never been asked for one before and don't really know what they cost. Is the old one beyond redemption? That idler pulley was also used on the 960 from 1991 to 1993.

Bill.

DeRail · Post by **DeRail** » 26 May 2009, 15:31

Will be going out to the boneyard to locate one of these pulleys, alternatively I suppose I can get the machine shop to install a new bearing into my current pulley. (It cleaned up real nice with a wirebrush

so maybe it would be worth it to refurbish this one) will have to find out the cost on this though. My father, an HVAC technician (so he had the gauges) read the pressure on the valves, which are R12, and the system is out of refrigerant, so next is to locate the leak.

Will keep everyone updated
Thanks!