Hey,

Its starting to get real wintery here in the midsouth, and like natural it gets cold quick and then my heats starts acting up. After being fully warmed up in the driveway it would take 4 or 5 miles before I could get the heater on. And to get it on; you'd have to push the defrost button and let it stay on for a minute and then turn it off. Eventuall the engine temperature would drop from around 85 to about 80, when it done that i could turn on the def and have heat for about 7 miles or so then it would start turning cold and you would have to repeat the cycle. So i replaced the thermostat today and I can turn on the heater without the car being fully warmed up and have a little heat, but it eventually turns cold. Usually about the second time you get the heat going again it stays really hot for about 15 minutes and then gets cold, but it comes back quicker. Also I have no heat at idle. Anyone have any suggestions on what I can do to keep it hot in the cab, because its getting really cold here.

Thanks, so much

Ty

Ty,
I am not 100% sure on this but I belive that the 116 has the dreaded servo type heater control system. If this is true then be ready to shell out some $ for a working unit. I have read some post however where some folks have bypassed the servo with ball type balancing valves, and then set for heat or no-heat.
You need to check and see if you have a servo, which is a componant with 4 heater hoses on the bottom, and a rather large head with about 8 vacuum lines attched. This would be the servo. If you dont have a servo, then you have the monovalve and the re-build is a snap as TANK suggested, In fact I did it last week, took all of 5 min.

Robert

The W116 does have an A/C Servo.

There is one thing that you can try that may or may not fix it, but set the dial on 65 degrees, then turn the heat on and leave it there, then switch over to defrost and leave it there for 5 minutes then switch back to the heater. Keep doing this for a while and it might help your ACC problems. Mine was starting to get bad last winter(mostly being too hot), and I did that and it has helped mine out alot, it has only acted up a few times this year (blowing out cold air).

Eric: I just noticed today that there is no heat in my 123. Thanks for the tip (even though it was for someone else). I'll give that trick a try tomorrow. I've already repaced the servo a couple times, so I really don't want to dump too much $$ into a "new" one again.

I checked up under the hood and everything. Is there any way to diagnose the servo, like any way to tell me that is my problem. I replaced the stat thinking that it would solve my problem but I was wrong. And I have a few questions.
1. Is there any way to by pass this thing?
2. Should I buy a new, rebuilt or find one in a junkyard?
3. Could a leaking vacuum line like the one on top of the unit
affect it's operation? IE there are two lines that were cut
when I got the car, is there an easy fix?
4. How hot is the servo supposed to get, because I felt up
against it and it was almost as hot as my engine?

Any help would be appreciated.

Thanks

Ty