ACC Question on 1980 300d
 

Recently the a/c system only started to work when on defrost. Also had trouble shutting the car off, unless I disconnected the green vacuum
Line and plugged it. This also affected the door locks. My servo is working as it moves when I adjust the temp gauge and the aux water pump is fine, compressor comes on fine to. It seems I need to track down the vacuum leak, but not sure where to start. Any advice? Also noticed the temp sensor hose is no longer connected, looks like a piece is missing, wire is still attached at the speaker grill. How do I know if my amplifier is good. Any suggestions ?
Thanks,

Are you positive the aux water pump works? Has the servo been upgraded?

An amplifier will go bad, if the aux pump freezes and it is advised to change it with the servo unit....

You need to replace the sensor tube, with out that tube....the system cannot sample the air....

Go to home depot and buy pipe insulation hose, in the plumbing section......glue the slit closed....cut to length and replace the tube...

If your have a vacuum leak in the system, you must find it....and technically it won't be easy...

First check all the vacuum hoses that run along the fender under the battery tray....that is usually where a leak will be found....

Next is to test all the vacuum pods under the dash.....remove both knee panels and you can see them all....use a vacuum pump like a mity vac and see if they all hold vacuum...

And start reading this....

http://www.imperialclub.com/Repair/Lit/Master/281/cover.htm

Thanks, I will get the sensor tube repaired. Servo is the upgraded one and it works fine. I assume that the aux pump works as it will come on, I am unsure of the amplifier, how can I test this? Everything worked good until I noticed the car would not shut down. I remedied this by plugging the green vacuum hose and car shuts off fine now. Where should I start checking the vscuum system? Is there a diagram somewhere?
Thanks

Here are some vac diagrams, not sure if anything pertains to your servo system.

http://www.peachparts.com/shopforum/diesel-discussion/105297-vacuum-diagrams.html


Charlie

Scroll down to section 2 lots of info.....as long as the aux water pump comes on and does work it should be fine....I pulled mine and replaced it with one I cleaned and re lubed......it is a wise decision to fuse it.....I think in all these articles it will tell you how to test the amp...

83 Climate Control System

Before you start with a vacuum diagram, you can begin by simply making a careful inspection of every vacuum connection. In my experience, nine out of ten times the problem is simply that a line has pulled out of a junction fitting, or something has cracked/broken with age. As the rubber junctions age they may no longer seal properly either, and that can add up (some people zip-tie every junction connection).

This is doubly true if you just did any work under the hood. I have pulled apart or damaged vacuum lines more times than I want to admit, doing unrelated things.

If everything seems to be fine, my suggestions for usual suspects to start with are the big yellow vacuum splitter valve (not sure of correct name) and/or the door lock circuit.

If the connections seem good, you could also double-check that your vacuum pump diaphragm is healthy (undo the main line running into the booster and put a vacuum gauge onto it).