w126 cabin sensor not sucking air - odd problem & fix

[dhjenkins]

I decided to finally do a little 'work' today and checked out my cabin temp sensor. It ohmed out fine, but the little hose wasn't pulling any vacuum.

I pulled the panel from under the dash and found the motor.

It was running - backwards. It was basically pushing semi-tempered air across the sensor instead of drawing in cabin air across it.

I popped off the harness connector back, switch the two leads, re-connected, and presto; it now passes the "paper test", in that it can hold a small piece of paper up against it while activated.

I have no idea why it was like this - the previous owner was not a "fiddler", but it does explain why the system was always a little slow to bring the cabin to the desired temp (in heat - A/C is currently not running).

Just thought I'd share...