Pre-monovalve ACC Help needed desperately!!!
 

Hey All!
Here's my issue (still after hours of searching the forum!):
I have a 1980TD (123 non-turbo). I have no heat (even on defrost), though all the settings work fine (as far as volume and placement of air). I have tested my aux pump (barrel shaped thing in line in front of the servo) and it is fine. I have pulled my servo (the spaceship looking thing in front of the air cleaner) apart and it seems to be perfectly functioning (and definitly not as old as the car) with all diaphrams and motors/gears functioning as they appear they should. I have no vacuum leaks that I know of (as in no other systems are giving me any trouble). I DO NOT have the mono valve on the firewall by the battery (the diaphram there is also in good shape through). So.....HELP!
What's Left?!?!?!?!?!?! :confused: :mad:
I have heard mention of some other sort of monovalve on this type of ACC that is like 10hours under the dash ( :eek: ), but I don't know what it is called or if these problems correspond with said valve:confused:...Or where to find the damn thing for that matter!
PLEASE HELP!
Anyway, thanks in advance.....
God I love over-engineering......
-Matt-

Matt, did you ever get help on this?
 

Found this post way down the list with no replies. Did you ever get any help with this topic?
btw - On the 1980's models the acc servo unit is the only valve that controls the heating etc...
There are a number of items that can be checked under the dash but there is no hidden valve for controlling the heat.

The system is designed that the acc servo receives inputs from various measuring devices within the car and this in turn tells it to open or close depending upon the amount of hot water that the core needs to get the cabin up to temp. The fender side pass thru on the acc servo is just that a pass thru and the engine side is where all the water flow adjustments are made.

There is a temp sensor that controls the on/off of the system on the fender side but this is overridden by the deforst setting.
Defrost is the default with max heat so if this setting is not working then you will need to start at the water flow fucntions and head up the list of checks from there.

Let us know if you need help...

There is also a amplifier for the servo behind the glove box -- if this is bad teh servo won't work even if good, so you get no heat.

They usually get fried when the sevro cracks and locks up. Sounds as if your servo was replaced, but possibly NOT the amplifer.

Get in touch with Performance Analysis in Oakridge, TN -- they rebuild the servos and can help you out.

Peter

Shoot me your e-mail address
 

I have a diagnostic guide that will help out a great deal. I'll be glad to e-mail it to you.

On quick thing to check,,,,,,,,,,,, coolant level.

JCD