Does the 260E have a mono valve? Or is it just diesels? I could go out there and look but I'm not able to at the moment and it's on my mind to ask!

Heat is *ok* but could be warmer when our is set at '22'. One issue is that I get air blowing thru the center vent...

__________________
Dale

124 have a "mono-valve" located close to the battery. It is a different design than the ones used in 123 and 126 cars, on these 124 cars the entire valve would be replaced rather than just the plunger/diaphragm unit.

The ACC dash unit controller is the weak link in the climate control chain, rebuilt is a reasonable choice and sometimes a solder reflow will get things working if you're solder iron capable.

Yes,I saw it there in front of the battery. I had a W123 several years ago and I remember having to fiddle with the mono valve - seems I replaced the diaphragm. So I checked at Pelican Parts and I can get a new one for about 130 bones

__________________
Dale

Before you replace the monovalve, unplug it then check whether you get more heat. If you get more heat, the problem isn’t the monovalve.

Check also if you get more heat in defrost mode.

Sixto
98 E320s sedan and wagon
02 C320 wagon

Thanks Sixto, will do that in the morning to see what happens...

__________________
Dale

In the Economy Mode with selector wheel set to Max there should be no air coming from the center vent.
Also in Defrost Mode, no air should come out of the center vent.
If you do, you may have vacuum pod, switchover valve block or push button unit problems. The pods crack with age, the switchover valve block suffers from solder cracks and the PBU can have a variety of problems.
I would see what is causing this before you throw money at a new monovalve.

Doing all the above 'tests', I get air coming thru the center vents.

I do hear a good bit of clicking behind the glove compartment so not sure what's going on there... Any suggestions for my next steps(s)?

Dale

__________________
Dale

Has this car always been this way with the center vents? How long have you had it?

The actuator that opens and closes the center vent is difficult to replace so some folks wedge it open and use the dial to manually set it. Some like me like the option of warm air through the center vents.

Clicking by the glove box is probably the solenoid bank that directs vacuum signals to the ACC actuators. It’s normal to hear clicks and movement when settings change but random clicking can indicate a tired PBU and/or faulty temp sensors.

Sixto
98 E320s sedan and wagon
02 C320 wagon

@Sixto... I've had this car a bit over for years, however,I purchased it for my two teens to use until they were wanting to buy their own cars. Well, they have both moved on to their own purchases and I have it back as my DD. That said, I am really learning all about its quirks etc and the center vent thing is one of them.

I just didn't have the opportunities to look into many of the issues like this when they had it because it was always on the road so to speak! I believe the center vent issue had been this way since my ownership. They actually didn't complain about the heating as much as the difficulty starting it. But I did work most of those bugs out and even my recent install of the EHA valve had made this car purrrr

Dale

__________________
Dale

So I unplugged the mono valve and send to throw out a bit more heat.

How would one go about checking the switches behind the glove box?

Dale

__________________
Dale

....'seemed'' to throw out....

__________________
Dale