Hopeless

My heater and air conditioning doesnt seem to work on my 85 500 sec. I dont know if it is a switch problem or if the whole thing is toasted I just got the car- so i'm not sure whether or not it ever worked. Does anyone know what might be wrong? When i turn the car on and turn the defroster on- the defroster warms the car right up- but i have to be sure i let it sit for a while or it will not work. When i turn the car off however, it smells like there is something burning. Are there any suggestions? And if you could- do you know where i can get a schematic of the heating/ air conditioning system? I prefer to do it myself, but i know it is illegal for unliscensed individuals to work on air conditioning units in some states. Any help/suggestions would be greatly appreciated.

Thank you very much.

braverichard

First of all, fixing your malfunctioning heating system is not illegal in ANY STATE. It is dealing with air conditioning, and most importantly, dealing with the different types of refridgerants, that you need certification for.

Anyway, I had to troubleshoot the same thing recently in my 500SEL. You better take care of yours soon before it really gets cold.

1) What do you mean by "When i turn the car on and turn the defroster on- the defroster warms the car right up- but i have to be sure i let it sit for a while or it will not work."? Do you mean that if you don't let it sit for a while just cold air blow out of the vents or that nothing happens until after a while? If it is the former, then that's normal. The heat that comes out of your car's heating system is heat from the engine coolant, so the car has to warm up before heat starts coming out. Explain if you're referring to the former or the latter.

2) Do you mean that when you put the climate control on heating mode for the car's vents nothing comes out of the vents?

3) Do the buttons on the climate control unit light up at night with everything else?

4) What do you mean by the schematics of the system? Explain fully. If what you're referring to is what I think it is, I can send you the stuff.

Hopeless

1) I am referring to the former- When i turn on the defroster, it blows air- just not warm air. If i turn the car on and leave it running with the defroster on for 15 minutes or so- it blows warm air. However- i turned my car on and drove it- (i was real easy on it so that it could warm up)- and i took two 6-mile trips, in that time it kept blowing cool air.

2) When i put the climate control on heating, (not defrost) nothing happens- it will blow air- but its cool. And this is after i have been driving it for a while. Even when i have the entire climate control off- i get cold air coming through my vents- i have to shut them.

3) Yes- all of the buttons light up fine.

4) What i mean is the drawings/pictures/diagrams of the system. Something that tells me how it is supposed to work so i can try to find the problem and fix it. Like a heater repair manual for my car.

Thank You very much-

braverichard

1) You could have a malfunctioning monovalve. A good first step would be to disconnect it and see if anything changes I guess.

2) My greatest fear... might be your vacuum lines. I'm not certain about the cause of this problem, but I'll be once I get back home and check out the diagram of the entire system.

3) Since your buttons light up fine and the unit always kicks in when used, then we can safely rule that out as the source of the issue.

4) I can get you all the details in the service manual once I get home tomorrow morning. Just check your e-mail.

Hopeless

Okay cool- I'll look foward to it.

Oh- by the way- i just enabled the option to be e-mailed by forum members. Sorry! If you have already sent the info- i'd appreciate it if you could send it again.

Sorry for the inconvenience and thanks-

Hopeless

MBenz

I have almost the same problem on my 95 S500. There is no warm air out from the passenger side even I have the dial knob at 85 while driving. The driver side is ok. All the lights and buttons on the center console are working.

I took my car to the dealer. It costed me $180 just for the dealer to tell me that my climate control unit is malfunction and the replacement is $2000+ on this.

This is how I deal with my situation. I have to turn the knob on the passenger side to HI in order to have the warm air but it's too hot in awhile. I tried to use the red button on the upper part in between the two vents, itseems only cold air out. Please help, I don't want to spend more than $2000 on this repair. It's way too much.

Is there any ways that I can take the unit out to see what's loosing inside?

Thanks