My son just gave me his 1987 560SL. I am new to this forum and need help. I am getting no heat, yet the fan is working and the a/c is OK. What should I be looking for. Living in the east, means I need to fiz this before the cold weather moves in. Someone told me to check the monovalve. I took out the inside of the valve, and the rubber seems to be in shape but I don't know what to be looking for, or if that recommendation is correct. Please help. Thanx

but did you check the coolant level?

and has the engine been overheated before? if so sometimes that loostnes stuff and the heater core plugs.

good luck

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The car does not overheat. It reads about 90-95degrees. And the fluids are fine. I just get cold air out of the vents.

I don't have a whole lot of experience with the older cars, but my understanding is that when the monovalve fails, it fails open for safety reasons allowing coolant to flow for defrost function. Feel the heater hoses when the engine is at operating temp to see if coolant is moving back there (don't burn yourself of course). You might have a clogged heater core. Nothing else is really coming to my head, but when I think of something I will post it. Good luck.