It seems my Air-conditioning systems has developed a random occurrence of blowing heat through the defrost vents while blowing cold air through front dash vents. The new feature (AC/Heat condition) doesn’t occur consistently.

One other condition that has puzzled me regarding the A/C is when the engine is under load (going up a hill) the air flow will cease.

Last, it seems the car has a noticeable “whining” noise when the A/C is operating.

I’m unsure if all these condition are related, but if anyone else has had similar problem or can offer me insight into my problem – your help would greatly be appreciated!

92 400SE W140

Thanks in advance.
Russell

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML