Well folks, I think its time to throw in the towel. I frequent this page and you guys are good! There is lots of great info, kudos to all.

I have a '80 300TD which needs lots of work but I'm determined. The A/C on the other hand needs a pro. This is how its gone: Dash off, ACC new, AC Servo new, Push buttons new, AC comp swithch new, traced wiring with schematic x2! She only blows on DEF and only as hot as she can. Fan works, nothing else. I've posted a few times will little response and local AC guys just don't seem to want to help. I gave it the old college try, if I missed anything PLEASE let me know!

I hope to get her in shape to post some pix with all of you sometime. She's no great shakes now. I look forward to reading your posts when I'm not on the road! Thanks

Todd

There's a Control Amp, located near the glove box. This might be bad, and causing your problems...

Why don't you start a little back of this post... what were the symptoms, the condition of the ac overall... had it been open, if so how long, are you using r12 or 134 or what? Does the compressor cycle on at any time? did you flush the system ? Did you put in new reciever dryer ? ... you know... that sort of stuff... we are blind except for what you use words to share with us... not easy dealing with AC anyway..
Why was it you tackled those buttons ? What were the symptoms etc.... ? 1980 could be rotary or piston compressor.. which do you have ?

Will the pic be with her all ablaze? I recommend 400ASA if you're taking pics of anything chared.:p

Do you even hear the AC motor coming on? With our Buick, it was only kicking in intermittently (but never blowing cold). In order to recharge it, the motor had to be running. Which fortunately did happen at the time when the repair guy was looking at it. Once it got recharged, the motor never cut out again.

Good luck with it!

__________________
Natalie

You didn't mention Monovalve...didya?

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85 300CD Signal Red/Tan sold
83 300D Manganese Brown 109K
97 E420 Midnight Blue 197K sold
98 BMW 328i Vert White 100K, sold
95 BMW 525i White 125K, sold
93 BMW 525iT Red 193K, sold
95 E320 Green Wagon 125K, sold
94 E320 White 127K, sold
85 300SD 156K Grey (Annie), sold
84 300D Lapis Blue 170K (Judy), sold
99 ML 320 Black (lease), 1998 C230 White (lease)
00 Honda S2000 Red (lease)
86 Mercedes 300E (sold)
84 Porsche 911 Red (sold), 1965 Porsche 911 White (sold)

I was under the impression that '80 300D's didn't have a monovalve. In addition, I always thought that a bad monovalve would make the heat not work very well, like what happened to my '85 earlier (I was getting heat sporadically, but the a/c works great).

I wish I had more to offer, but I don't know much about the earlier system...

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2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
Spark-free since 1999

Well, when I got the car someone already tried the cheap way out. The temp sensor in the blower box was briged and the ambient temp sensor had a switch put in it to disconnect it from the system .

The compressor is a centrifugal rotary type and looks to be rebuilt. The compressor is painted flat black and you can see new bolts on the front of the clutch. The system has been changed over to 134 (bigger freon valves) but the dryer looks old.

Symptoms: blower only comes on with DEF or BI-LEVEL, compressor never came on and center vents have never opened. I went after the push buttons because the green and the grey (two diff wires) wire terminals were melted. I think I just learned that the 12v Vac switch (3 metal gold colored) sits right behind the terminals and those switches appear to get almost too hot to touch. When I put 12v to the switch (unplugged) I can hear all 3 click. All the yellow or white vac switches close when tested with an ohm meter.

With this system there is just no "red flags" that point in any one direction. I hope this explains more but I think I'm starting to comfuse myself

This year has the chrysler servo (which is new $300+) so there is no monovalve. Does anyone know the extent of the A/C system on those discs? The manuals I have only cover body and chassis, thats where I traced the eletrical.

There you have it, Thanks again all.

Todd

To 123c, this control amp, is it located sort of just laying there when one removes the glove box? I took out my glove box to fix the piece of crap hose to the temp sensor and found a box just kinf of sitting there on the vent tubes. Gave it a little love pat and left it alone since I didn't know what it was. Thanks.

rmmagow,
I am sure that was it, I messed around with mine last fall when I fixed the foam hose in my car. I am still trying to figure out if I need to replace mine, or the A/C servo. The older ACC systems can be such a headache. Mine will work most of the time, but sometimes it will go to full blast heat, when I want cooler air, and sometimes it will blow out cold air when I want hot air. I am going to make sure that the next MB I buy won't have an A/C Servo

Same problems on my 1980 300D.
Eric,
One thing that I learned on the heat fluxuations thing was that the temp sensor needs to be correctly connected to the blower and that with my dash cover it wasn't getting air to it...

Really had me going for a while but I finally figured that one out...duh! Oh well I guess I had a senior moment there.

As to the controls and troubleshooting there are a couple of main items that you can start with and there is an acc doc floating around that can help with the basics.
if you need a copy send me a PM with your email address and I can shoot over a pdf of that doc.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique