1984 300sd heat issue

[74baja]

Hello,

My '84 300sd has a climate control problem. The vents seem to constantly emit heated air, regardless of how I adjust the temperature wheel. The blower turns on and off, and changes speed, and at least some of the vent controls seem to work (changing between floor vents, dash vents, etc.) What is my issue with the constant heat? Is it the mixer door or something?

Thanks,
Jack

[tangofox007]

Checking the electrical connector on the monovalve would be a good place to start.

Originally Posted by 74baja

Is it the mixer door...?

No. It's a monovalve problem, either electrical or mechanical.

[74baja]

Thanks for the response. This car is fairly new to me- where can the monovalve be found?

Thanks

[tangofox007]

Engine compartment, false firewall.