So I'm still deciding what to do about the AC on my 88 244. Found a good deal on r12 and it hasn't been converted so that's definitely an option. But I want to know if the compressor even works. Tonight I went out and took the cap off the low side and bumped the valve ever so quickly. It still had pressure, so I took that as a good sign! (now someone will probably let me know that was the single dumbest thing I could have done)

So I was looking around the compressor to see if anything was obviously wrong and found that the black wire that runs to the front of the compresser (right behind the clutch) was cut in half. A-HA. I thought I found the problem. Quickly spliced the 2 ends together but the compressor didn't turn a bit. I did have the AC cranked to red and the fan on 4.

Can anyone let me know how to start diagnosing the compressor? My guess is the freon level is so low that the compressor is not turning on. Or there is an electric issue somewhere. I just emailed the last owner to see if he ever had AC. How could I get some r12 in the system if the compressor isn't running and without ruining the AC system?

Thanks.

 

The easiest way is to put a set of gages on the system and see what pressures you have. That will tell you if you have some or any freon in the system. If you still have some then look at the receiver/drier or accumulator and you should find a low pressure switch. Unplug the connector and use a jumper wire in the connector. Turn on the AC and see if the clutch works. If so you most likely have low freon , check the sight glass in the R/D and see if you have bubbles or an oil streak in it. If you have no freon then start looking for the leak. If you have a leak you will have to replace the R/D anyway.

 

Awesome, I was hoping there was some way to test the clutch. Thanks for the help, I'll do this and see what I find. Might be a few days until I get the results. (not worth it to work outside today on the east coast.)

 

to test the clutch, connect that black wire to +12V with a jumper....

careful, I had a compressor that was frozen up, and when the compressor clutch was accidentally engaged, it burned up the belt which knocked out the power steering. We disconnected said wire on purpose.

the signal path is .... dashboard AC switch outputs +12V when its switched on, that goes through a low pressure switch in the dryer/accumulator, then through a high pressure switch in the condensor manifold (near the radiator) then to the clutch wire you have. so, key on, A/C switched on, take a volt meter, clip the - wire to ground somewhere, and check for voltage on both pins of that low pressure switch. if no power on either side, time to dig into the dash. if power on one but not the other side, either you have low pressure or that switch is bad. if power on both sides, check the high pressure switch on the condensor manifold, again, no power on either side, its the wire between the switches, power on one side but not the other, its probably a bad switch or you have too high pressure, and power on both, then its the wire between that switch and the clutch (one part of which is the one thats cut). if either of hte pressure switches shows juice on one side but not the other, you can verify by shorting said switch, that should fire the clutch.

 

pierce, wow. Amazing stuff man. Thanks a lot.

So, should the black wire also show 12V. Since it was cut right before it enters the clutch on the compressor, could I just test the 12V there where it was cut/frayed and see if it has 12V? If it doesn't show 12V then start working backwards? Or would that give me a faulty result (false positive or negative)?

 

yeah, thats equally valid. I think I'd still test the compressor by jumping +12V to it (say, from the battery + terminal) while the engine is running to ensure that the compressor turns and isn't binding or something...

 

pierce you nailed it. I got an email back from the guy I bought the car from. He said last time he used the AC it broke a belt so he took it to some shop. They told him not to use the AC again or the belt would break again. They probably also cut the black wire.

So, what does this mean? Do I need a new compressor or can I take that one off and replace some stuff and I'll be good to go?

 

probably a new compressor. its a very generic compressor, shouldn't be too hard to fit a replacement.

and then, of course, recharge the system. and if its pre-1993, its probably an R12 system, so you'll either need to convert it to R134a or try and find R12 (which hasn't been made in 15 years). the conversion isn't that bad, its a new dryer, new expander orifice pipe, and a thorough flush of the old lubricant out of the system. the kit comes with new style high and low side orifices for charging.

 

can anyone point me to a good "compressor replacement" step by step tutorial? At this point do I need to do anything before I have someone flush all the old crap out of it? Anything else I should replace besides the drier?

Here's my plan, let me know if it's faulty or needs steps added to it.
1. Have someone flush the system well of the old compressor particles and old oil/refrigerant that is still floating around. (how much to shops charge for simply flushing an AC system?)
2. Remove drier and compressor
3. Add new compressor and drier
4. pull vacuum for a good 45 minutes
5. let vacuum sit for overnight to test for leaks
6. add new refrigerant
7. enjoy new cool air

Does that sound right?

Pierce, when you say it's a generic compressor, should I be looking for a compressor make and model, or do you mean it was used on a lot of volvos. I'm just wondering if I could find the same part labeled for, let's say a toyota, for less money than by searching for a "volvo 240 compressor".

 

I've heard other folks say the same compressor is used in numerous cars, up to and including some fords. now, I don't know if you'd have to fab a custom bracket or whether those are a bolt on application.

the stock Volvo part is 6848077 and fits all 240/740/940 from 85 to 1990, and is $292 at Tascaparts.com (real volvo part). FCPGroton sells the OE Seltec for $289. These are R12 compressors so the R12 oil has to be drained and rinsed out and replaced with r134a compatible oil.

I'm sure you could find a used one for *way* cheaper from like a piknpull or whatever, of course, you'd be taking your chances as to whether or not it works... if you found it in an R134 converted car you could probably snag the dryer and reducer pipe too.


re: your steps, pull and toss the dryer, THEN use a compressor to blow the oil out of the evaporator to flush the old oil out. ditto use the compressor to blow out the oil from the condensor, and the lines. also a r134 conversion kit includes all new o-rings as the r134 compatible lube will eat the original o rings.