I have a 1992 300D 2.5 diesel the heat will not cut off. I have the climate control off but heat still comes out the vents and on the windshield?

Faulty monovalve?

Sixto
87 300D

There is an easy way to check.

Remove the connector and hard-wire 12V to the mono-valve. If you do not have heat anymore then the valve is OK. CCU/wiring is at fault.

If you still have heat then mono-valve is not closing.

Good luck.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

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