Close heater control valve for summer to maximize AC - Page 3 - PeachParts Mercedes-Benz Forum

Cr from Texas · #31 06-12-2008, 10:01 PM

I wonder if the failure is due to my choice of coolant. I've always used Zerex and only recently learned reading this forum that the preference is a red MB coolant. Is that a dealer only item?

#32 06-12-2008, 10:35 PM

Actually, the correct coolant is the amber MB stuff, which is the same as Zerex G-05.

Cr from Texas · #33 06-12-2008, 10:39 PM

Thanks,
I've learned more about my car in the last four months on this forum than I did in the 25 years of ownership.
I'll have to look at my Zerex bottle to see it's the right type. I know is was listed for aluminum.

SD Blue · #34 06-13-2008, 10:58 AM

Quote:

Originally Posted by Craig

I've never tried to take the check valve apart either, but I believe it's only function in to prevent back-flow into the heater core when the monovalve is de-energized with the car shut off. When the engine is running, the water pump should not allow back-flow anyway.

The reason I'm a little suspicious is for a couple of reasons. The a/c, on occasion, is only moderately cool and in the winter I can hear the heater core filling with water when heat is turned on. With mention of this check valve, I wonder if the two are related?

#35 06-13-2008, 11:10 AM

Quote:

Originally Posted by SD Blue

The reason I'm a little suspicious is for a couple of reasons. The a/c, on occasion, is only moderately cool and in the winter I can hear the heater core filling with water when heat is turned on. With mention of this check valve, I wonder if the two are related?

That is strange, but I don't see how the check valve would be the cause. Also, I never hear my heater core; I wonder if you have air in the system someplace. If the AC system is working (compressor is engaged, top AC hose is cold), I would still suspect that the monovalve is letting hot water into the heater core under some conditions.