I hope someone who knows more about this than I do replies. Under the guidance of my two friendly parts men, I poured about 2/3 of a bottle of AC oil into the accumulator/filter. I put the remainder into the plug on the side of the compressor. Keep in mind that this was a rebuilt compressor and it was off of the car when I poured oil into it. For one on the car, you'd have to put it into the lines. I think you can buy refrigerant with oil already in it.

 

from what I have gathered you don't want too much oil in the system any more than you want too little. the only way to get the right amount is to evacuate the system, flush it out with solvent, evacuate the solvent, then charge it with the right amount of oil AND refrigerant. professional gear can do this, driveway mechanicing with aerosol cans can't.

also, the reciever/dryer should be replaced if the system has been breached and air has gotten into it, as the dessicant in the dryer will have absorbed water from the air.

 

I have replaced almost the entire ACon my 740 sedan. If the compressor is shot, i have found used ones that run on R-134a for about $125 and they work. My father just happened to know a AC guy and we put the system on a vacuum and found that it leaked from the rubber lines. In total, the lines cost about $80 brand new, filter dryer about $20, and a compressor for about $125 all plus tax. If you wanted to buy a new clutch for the compressor, it will cost about $80. The way that I thought about it was that I had to take the compressor out anyways, so why not spend the extra $45 on a used compressor all together. Need anything else, just ask.

 

What kind of oil/refrigirant do use for the bosch compressor.

 

all 240s, 740s and 940's came with R12 AC refrigerant and R12 compatible mineral oil. R12 is no longer manufactured, although its often available on the grey market. many 240s and 740s have been converted to R134a, which requires a different 'ester' oil and new receiver/dryer and a different orifice, as well as replacement o-rings and seals..

 

I have a 93 wagon. Which came with r134a. My compressor whines/howls when I hit the gas. And accerlate. I checked the vbelts their in spec. I see a brass fitting on the backside of the compressor I'm assuming that s where you fill with oil? Or like above use oil/refrigirant.

 

see my post #22 in this thread. the only way to get the right amount of oil into the system is to evacuate the system, flush out all of the oil with solvent, evacuate the solvent, then refill the system with the correct amount of oil and refrigerant. The amount required should be on the sticker near the reciever/dryer. this is a job for someone with proper A/C servicing equipment, not a driveway job.

 

Hey everybody! About 2 months ago I had the air conditioning in my car completely serviced. Got a new compressor, dryer/receiver, orifice tube.. etc etc. Well, the A/C works sometimes. One day it was a little warm about a month ago, so we decided to try the air conditioning. It seemed to work for a bit, then taper off. I kept turning it on, then off. It wouldn't work. So we figured it leaked its coolant.

Fast forward to today. It was hot out. I figured, why not try the A/C. Not like it'll hurt anything. To my surprise, it cooled for a good 6 minutes or so, then tapered off. My philosophy is if it leaked, it shouldn't be cooling. I tried running it on the way home to no avail. When I got home in my driveway, I turned the car off, put key to position 2, ran to the engine compartment, and listened. The clutch is engaging. So I started the car, turned the A/C on again, and witnessed it engaging. So I drove it. It cooled off pretty well for about 5 minutes again. It then tapered off again when I got back in my driveway. I got to see the compressor disengage. I think that it's odd the compressor is disengaging even though it should be cooling. So, I'm thinking relay or temperature sensor. But what do you all think the problem could be?
Any help is greatly appreciated, especially since it'll be hot soon.
Thanks,
Evan

 

the two temp sensors (one at the reciever/dryer, and one at the radiator manifold) are both open/close switches in series with the compressor control signal that comes from the dashboard controls. so if you think the AC has shut off, try shorting those two switches, and see which one re-enables the compressor.

 

Hmm... How do I go about shorting them, and what am I looking for?

 

unplug the connector from the switch, and connect the two pins of the cable together with a jumper wire. if the compressor starts, then that switch was preventing it.

I believe the switch on the reciever/dryer is for low freon pressure, while the other one is for high radiator temp. but thats from memory, I'd have to dig into the greenbooks to confirm.

 

It was the switch to the A/C Receiver Dryer... It wasn't plugged in all the way. You haven't a clue how happy I am!

 

well, *that* was easy!

 

Indeed! I'm prepared for the heat of the summer now.

 

Well, A/C decided to not run today. So, I pulled off onto a side road, jiggled the switch mentioned earlier, and it kicked on. Figured it just got lose. About 5 miles or so down the road, no A/C again. It was still the switch, only this time I took it off and inspected it. There was a little wire stuck in the female parts to contact the male parts. This explains the come-and-go connection. So, what I did was take some more wires, braid them together into a strand with a decent amount of thickness, and stuck it in. It works for the time being. However, I'd like a more permanent solution. I don't necessarily want to ghetto rig my Air Conditioning. Plus, I'm pretty sure the wires are causing excess heat on the switch, as it gets hot. Any suggestions?

 

its just a spade lug connector on the switch, isn't it? replace them. probably a standard 1/4" spade lug would fit fine. The key to good electrical repairs is a high quality crimper, for insulated terminals I prefer the ratchet kind. match the connector to the wire size too.

 

OK! So, yet another issue. I ran the A/C tonight, and noticed it lost its cool. Also, there was little to no air movement, even on high fan setting. I checked to see if the compressor was running, it was. I then looked at the receiver dryer, and to my horror it was frozen white. So, I figured the evaporator froze too. All of the lines were frozen! Any ideas as to why everything was freezing? Turned the A/C off, and it thawed almost immediately.

 

not enough air flow past the evaporator ? the pressure switch should have shut the compressor off when it froze up. make sure the 'recirculate' button isn't pushed in, so you're getting fresh air blowing through the a/c, the dashboard vents are all wide open and the fan is on 2 or 3. just turning on the AC should make the cabin fan run on low even if its switched off.

 

Alright. I bet its the switch not letting the compressor turn off. Since its shorted all the time.

 

I've purchased a new switch! Now, am I able to remove the old one and put the new on in on my own, or is the coolant involved? Would I have to take it somewhere to have it done?
Thanks!