Thanks for those who have posted in the past, this has been a end of the rainbow plethora of information. I am very much indebted.

Now for my Brain teaser: I have a300sd 1982

seems my 4th gear doesn't like when I use the air conditioner, at least not until i have driven the car for several miles.

Without using the a/c, the tranny is a little rough shifting from 1st to 2nd, but works thru all gears effortlessly.

My thought is there is a draw on the vacuum when using the a/c, but why???

Likewise when I use the heater, the car will not shut off except using manual button in engine compartment.

You will probably want me to test the vacuum pull from the pump? which i have yet to do.

Thoughts?

All are welcome