87 300sdl I converted last year to 134. It worked fine until now. I am getting hot air blowing constantly with ccu off. I checked fuses and found #5 blown. I replaced it and hot air stopped blowing. I checked ac low pressure line and have no pressure. I also can see the compressor will not engage. I can manually move the clutch, so apparently it is not frozen. What would you reccomend I check? Is there a punchlist or a procedure to follow to repair ac? Any help will be appreciated.

Am I posting this question in the correct forum? If there is one I could expect better results I will post it there. thanks

I do not know much about the A/C system but if the A/C clutch is not working I would check to see if it is getting voltage to the connectors when the A/C is on. If it is not getting voltage you have an electrical problem.
Also is there a fuse that protects the A/C electrical circut; if so check that.

__________________
84 300D, 82 Volvo 244Gl Diesel

You mentioned your problem in your first post. You said the low side pressure was zero I believe. That will keep the compressor from coming on. The oil for the compressor is carried by the Freon. No Freon, no oil coming into the compressor, no oil coming into compressor the ccu will stop the compressor from self-destructing.
Paul

__________________
84 500 SEL (307,xxx miles)

I am having similar problems but I have pressure at the low side.

When you converted I assume you got a new compressor and drier?

You obviously have a leak somewhere if you have no pressure.

__________________
'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

You're leaking 134 from somewhere if you're pressureless. You can either juice up the system and use a sniffer to look for leaks or add dye and use a blacklight to locate the source of the leak. It's possible that you'll be able to see the compressor oil at the source of the leak(s) with the naked eye, but I wouldn't put all your eggs in that basket. Once you find the leak(s) you'll have to evacuate the system, replace the seals and/or line(s) involved (or possibly the component involved ). If you don't have an a/c machine at your disposal this process will really have to be done at a shop that can fill/evacuate/fill the 134. It may even be the law where you live that a qualified shop work on your a/c system.

__________________
Ich muss geisteskrank sein.

The 1983 300 SD: "Old Smokey" (Hilda) Quarter Million Mile Club

The 1986 420 SEL EURO: "¡El Conqístador!" (Helmut) Trunk Triangle Club

The 1995 Cadillac Coupe deVille: "Schlag Kaltluft" (Shaft)

I had the system evacuated and charged last year with 134 by a shop who said I didnt need a new compressor or accumulator. He said the oil in the system for r12 is compatible with the 134. He said the evac. and the recharge with 134 and oil is typical. No parts need to be changed.
When I just now checked for low side pressure there is 0 and I tried to add a new 8 0z can of 134. The system would not accept any recharge. I ran the engine with ac on lowest setting. The system would not take any freon. The compressor was not running. Even with a leak and compressor not running should the system accept the recharge. thanks for all your comments!!!

We do not have accumulators on our cars. That is used for a CCOT system. TXV systems such as ours call the reservoir a receiver. But most shops are used to American iron, which pretty much all use CCOT systems.

You NEED a new dryer to convert to 134a. The 134a-compatible dryer works just fine for R12, but the reverse is most definitely not true. Your old dryer may be restricted as a result, or even worse, it could have spewed its guts into the evaporator.

You can't expect "the system" to accept refrigerant with the engine running if the AC compressor is stopped, unless you take special steps. You CAN introduce liquid refrigerant into the static system (car turned off), and that is what I prefer to do. But expecting a non-rotating compressor to pull refrigerant into the system is expecting magic.

If the receiver spewed its guts into evap. is there a way to clean, repair, or even inspect to determine if that has happened? Im not adverse to magic or miracles. So any reccomendations are appreciated.
I just started engine checked fuses and pressure. This time without any sign compressor was running, I have 65lbs pressure on low side. The pressure now seems to hold steady, even though I have not seen or heard the compressor engage!! There still is no cold air blowing, just hot. I should also state that the oil cooler had leaked, which I just repaired. The oil has sprayed over the compressor. Could this cause some malfunction?

If the compressor is not running, both service ports should show the same pressure. If there is any liquid in the system, this pressure is dependent on the temperature of the refrigerant only, and not on the level at all.

Oil on the compressor can really only hurt the clutch. The front seal isn't designed for petroleum oil, but you probably can't get enough motor oil on it to cause any trouble. I'm not sure, but it seems possible that a lot of oil on the clutch could keep the clutch from turning the compressor shaft, even though the magnetic coil is energized. I doubt that this is the case, and more strongly suspect that you have no current to the coil. Check for voltage there.

The only way to inspect the insides of the AC system is to flush it and look at what comes out. This is a huge procedure, but is certainly not impossible, nor beyond the means of a DIYer.

Not sure about motor oil, but I belive that a PS pump leak which bathed my compressor in PS fluid for a few months is the culprit behind my compressor seal rupture.

New compressor/drier time for me

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

thanks for your help. Ill check this afternoon for current to compressor. The oil did not build up on the clutch. It did cover the body of the compressor behind the drive belt.

i got a compressor for you

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.