Only heat coming out of the vents 190E 2.3
 

My heater seems to be stuck in the on position. I only get heat out of the vents and when i select cold air on the thermostat...nothing. My A/C won't turn on either, i can't get the compressor to turn on. It seems my whole climate control system is pretty dodgy. I don't think the vents open and close either when i press the different buttons to select the different vents. Should i just replace the climate control system or is there an easier way to fix these problems? This is out of a 1986 190E 2.3L 8V. Thankyou for your help!!!

I have EXACTLY the same problem! I have not looked into it, but now that it is getting warm out, it is time. I suspect that it is vacuum controller behind the glove box.

Could someone here confirm this as a good starting point. How can this be tested before buying a replacement?

Have you had your cooling system checked. You might have a freon leak.

I need to get the heat off first before i try to make the air conditioning work.

My 86 190E has the exact same problem also. I just got mine out yesterday and put the battery back into it (I dont use it in the winter) but AW, I was going to ask the same question. Where do we need to start looking for the root(s) of the problem?

maybe...
 

I am not an expert on this but here are some things the fixed similar problems in my '86 300E.

-hot air even with ac compresor on; replaced monovalve which controls wether coolant is going to your heater or not.

-air comming from every vent; vacum servos replaced, big job, dash has to come off (replaced evaporator while at it).

-A/C not responding, hot air; replaced climate control box.

Like someone before said, I would check to see if you have a freon leak first.

I don't know how things are up north, but here in florida the vacum servos rot after 10 yrs or so.

hope this helps...:)

Monovalve Maybe!!!!
 

Monovalve?
Sounds like could be a Monovalve issue and since that is the easiest to eliminate (5-10 minutes and a screwdriver) that would be a good place to start. You can get step by step instructions with pictures here:

http://mbdieseldiy.tripod.com/index.htm

Look under Monovalve replacement, its for a 126 but yours can't be much different! FastLane's got the repair kit if you need it. Good Luck!




;)

I know my problem is not freon. Mine is fully charged and having the AC on makes the hot air from the vents SLIGHTLY cooler. The charge lines are cold and condensing.

My thought is that the problem is the vacuum switchover valve. But this is only an educated guess.

Michael

Did you ever solve this? Was it the mono valve?

Haasman