A/C help on my new '83 300D - PeachParts Mercedes-Benz Forum

fromthe804 · #1 05-22-2009, 10:26 PM

So, I made the jump and purchased a 1983 300D yesterday. It's in great shape but the A/C blew out a couple weeks ago. It still blows, it just blows hot. Any suggestions? I heard that I might have to change out the seals and everything IF there's R12 in there. I'm not sure about that yet, but i'll update if I figure it out.

Also, in an unrelated note... Does anyone know what the far-left switch on the center console does? It looks like it turns on a light, but nothing changes when I turn it on and the previous owner didn't know what it was either.

Thanks, and I'm happy to be in the owner's club.

Keebler64 · #2 05-22-2009, 11:12 PM

As far as the AC, I'm in the same boat.

The switch however, if its like the w126 300SD, turns on the rear dome light above the backseat. took me a week in the dark to figure out there was a light back there. Your bulb could be out.

Jeremy5848 · #3 05-23-2009, 01:00 AM

If you have gauges and knowledge you can check to see if there is any refrigerant in the system; otherwise you'll have to take it to a shop. Mercedes put a low-pressure switch in the refrigerant line; if it goes bad, it won't allow the compressor to run.

Good luck, welcome to the club.

Jeremy

rscurtis · #4 05-23-2009, 09:24 AM

Stick with R-12 if the system was already using it. You may want to replace the compressor just to start off with a leak-free unit, and while you're at it, replace the expansion valve o-rings- that was the final leak on my '83. Don't even think about using any type of sealer- it's like getting married and having kids- no going back.

leathermang · #5 05-23-2009, 11:43 AM

Quote:

Originally Posted by rscurtis

Don't even think about using any type of sealer- .

You forgot to include the Receiver - Dryer... a must to replace any time the system is opened up..

for new people he was referring to sealers put into the system ... like radiator sealers... bars leak, etc...
These sealers are great at sealing up the Txvalve... not exactly the sealing people are looking for..

As it is put back together the orings need to have what some might think of as sealer put on them... NYLOG... in the proper color for your particular colored orings... this is just condensed refrigerant oil put on the orings so they can move according to the physics of the situation and seal properly.

fromthe804 · #6 05-26-2009, 05:20 PM

Alrighty, so I took it to a guy (who also let me know that it's already been converted to R-134, which is great).

He's a refrigeration guy, and he says that there's nothing wrong with the compressor or the refrigeration unit, but there's a switch in the heater that isn't turning off. So i can either put in a valve in the heater thing, cutting off the flow of hot water during the summer and opening it up again during winter, OR i can replace the switch. thoughts? oh and does anyone know where i can get a repair book for these kinds of cars? Can't find any on Amazon.

Thanks

tangofox007 · #7 05-26-2009, 05:31 PM

Quote:

Originally Posted by fromthe804

He's a refrigeration guy, and he says that there's nothing wrong with the compressor or the refrigeration unit, but there's a switch in the heater that isn't turning off.

Someone who doesn't understand how you heater operates is apt to jump to the wrong conclusion. On your car, electrical power is required for the heat to operate in the "OFF" mode. The problem needs further study; temp control with an ACC system is not that simple.