I picked up my 1994 E320 from the body shop yesterday. Driving home, I pushed in the EC button on the climate control as usual ... but got heated air instead. I slid the temp dial all the way in the blue zone -- but still received heated air from the far left and far right dashboard vents. The central vents (above the radio) blow comfortable outside air. Temp outside was only 70F, but my far left and far right vents were pumping 90+ or so. Engine temp was normal.

I played with the buttons and various settings and fan speeds, but could not get non-heated outside air in the EC setting. The only way to get cooler air was to turn on the AC ... or turn off the fan system entirely. AC works fine and blows cold air as it should. And of course I get heated air in the red zone.

One possible kicker: As part of the repair work I had done, the antenna mast and cable were replaced. Since I assume the cable must plug into the back of the radio, I'm wondering if the repairman accidently did something to affect the adjacent climate control system. If so, what? Any thoughts?

It's nice to have a working radio again ... but the heat is on!

When "SomeOne" has been fiddling around behind your console.
It sounds like the connections to the Mono-valve have been disconnected...
either @ the CCU or the Mono-valve itself.

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'84 300SD sold
124.128

Where is the mono valve on a 124?

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W123 1985 300TD naturally aspirated

Thanks for replying ... but I'm mystified by your answer, not knowing what a mono-valve is or where it is located, or how to correct the problem. Could you amplify on that please?

The mono valve is the hot water control valve for the heating system. It will default to open if there is a system failure so heat will be available in winter. The mono valve should be on engine side of firewall in the water supply hose to the heater assembly. It is large enough that it bolts to the firewall or engine compartment rear wall somehow. If it has been unplugged it will give full heat.
Bill

I had this problem in my 300TE and it was the climate control unit (where you are pushing the buttons). I had to resolder it.

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