Today was 105 heat index and I definitely need ac. My compressor is shot! Makes this screeching sound every time the clutch kicks in. Is there a good link on how to replace the ac compressor? Also, I know I need to change the drier and orfice tube. How about the condensor? What's the correct way to flush the system? Thanks in advance.

 

If you want to DIY this, changing the parts is easy but evacuating and recharging should be done by a shop as it takes special equipment (the evacuating mainly). Also a shop should check for leaks prior to recharging it. I assume you are going for a 134 conversion? You would have to change some O rings.

https://www.brickboard.com/FAQ/700-9...rsionPage1.htm

 

That is the plan. I'll have my mechanic do the filing and check for leaks. Is it me necessary to also change the condensor? Also which parts needs to be flushed? I guess I should run a dye in the system before taking the compressor off to check for leaks. Or should I do that after I've replaced all the o rings? How mangy total o rings do I need to replace?

 

you also should change the reciever/dryer unit, thats the beer-can looking thing near the firewall, that actually should be changed any time the AC system has been open to air. many r12-r134 upgrade kits also include the orifice doohickey.

R134a requires a different lubricating oil than R12, so the flush is to remove traces of the old oil. since you're changing the compressor, you just need to flush the evaporator and condensor, and the plumbing.

installing the compressor is about as hard as removing the belt, unplugging the control wire, unbolting the compressor, bolt on the new one, plug in the control wire, and reinstall the belt, tensioning it, then reconnect the AC fittings. the new compressor probably comes pre-filled with R134 compatible oil.


there *IS* a plan B, not technically legal (due to lobbying by the fluorocarbon industry)... so-called HC12, which is a blend of propane and butane... this is a BETTER refrigerant than any fluorocarbon, and its dirt cheap, but it can't be patented so the chemical industry has fought it. HC12 doesn't need any conversion, will work fine in a R12 system, and will cool better than R134a ever will. For all those who will scream 'its flammable', so's the gasoline your car runs on. the half pound or so of propane in the system will make a single FWUMP if it was to get out and ignite, nothing to be alarmed at, gasoline vapor fires are far more dangerous.

 

You can use Envirosafe to replace R12...

 

I think Envirosafe is another brand name for the HC12 stuff I described. a Hydrocarbon blend, basically propane+butane. very similar to backpacking 'gaz' fuel.

 

Somehow I didn't get past the part where the OP thinks he needs to replace the compressor. The symptom I read was every time he turned on the AC he would get a screeching sound.So did he rule out that the belt was tight or it needed replacement. Also did he put a set of gauges on it to verify the system was low or empty. When the basics have been explored then is the system R12 or has it been converted. If there is no freon in the system then you should change the receiver/dryer , orifice valve , o-rings and flush the system. Install the compressor (a new one usually has the right oil in it) and do a vacuum test and leave it overnight. If OK just recharge the system if not now the fun begins. Check the condenser after verifying all of the connections are tight. Also I would assume you checked all of the hoses to see if there was any oil on them. Once you find and fix the leak then charge the system based on the pressure/temperature charts. Good luck.

 

I rented a guage at Autozone but can't find the high pressure side. Anyone can tell me where it is?

 

one port is down near the compressor and condensor, and the other is on the side of the reciever/dryer 'beer can' by the firewall.

 

Is it this one I'm pointing at?

 

I believe that one is the low side port. the high side port is on a line right next to the compressor, down under a lot of other stuff.

 

No, the low side port is the one on top of the ignition coil. It's sticking out of the drier. So I wonder what this part is?

 

i just looked, my 92 740T (long ago converted to R134a with a factory kit) doesn't even have that port there, although it has the bracket.

 

I just tried to unscrew the black cap and it was under pressure. Foamy oil started to leak out and I quickly tightened it back up.

Anyway, do you have a picture of the high side port? I took the low side and it's at 90 psi with ac on.

 

That is the LOW pressure port and if you remove the cap and freon (gas/oil) escape then you have a problem with the receiver/dryer. You don't need to hook up the high pressure side (which is on the compressor) to see if the system is fully charged. Also you usually charge the system from the low pressure port. If you are leaking there then you need to change the R/D. It also looks like the low pressure switch is not connected or did someone just put a jumper on it to make the compressor run while charging the system.

 

I went to Enviro-safe's website R134a Replacement Refrigerant with Dye Can Details and Online Ordering at Enviro-Safe, Inc and I'd like to try this stuff. But first I have a leak that needs to be found and fixed. Have you tried their stop leak?

 

Huh? Wrong thread?

 

wow, wrong thread on the wrong forum a guy has stuffed a LT1 into a Mercedes E320 and having trouble with the starter circuit.... heh.

 

No prob, but since I got you here, what do you think of their stop leak? Ever used it? If it clogs up the system, what do you suggest to trace a leak?

 

I don't trust any magic-in-a-can-errr-stopleak stuff.

the standard procedure is to vacuum the system down hard, and fill it with some UV Dye, a/c oil, and pressurized N2 (Nitrogen), then run it, and check for leaks with an ultraviolet ('black') light while parked in a dark spot. find leak, repair, then re-evacuate the system, and recharge with your preferred gas.