'92 300e. Low temperature cabin heat

[dkveuro]

I've pasted this here from Tech forum 'cose nobody reads it !

Need a little insight on this problem please..........


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I am going to sell my 1992 300e so I am going to have to fix the low heat output....something I put off while I drove it..

My MB shop book does not cover the symptom as far as I can see....does anyone have an enlightening description of the job to correct the following..

When fully warm, blower runs fine and air volume is okay but the harder/faster the blower runs the cooler the air flow.
New heater valve fitted last year but it changed nothing......if you shut the blower off/low and run the engine for a couple of minutes the heat is there for 10 seconds or so and gradually cools off with the blower turned on again.

Temperature is just above ambient if system on HEAT/MAX/RECIRC'/AUTO.
In the summer it will cool until you need to turn it down/up ?....so the a/c cooling is fine......could this be a flap/flap actuator/vac' problem....and how easy is it to get to them.?
Have cleaned the overhead temp' sensor and suction fan is running.
I ran a water hose through the heater pipes and flow was not restricted.
Aux' pump runs okay.

.......any ideas ?


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[dkveuro]

............Bump.

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[dkveuro]

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[haasman]

I think you might be on the right triack with

"could this be a flap/flap actuator/vac' problem....and how easy is it to get to them.?"

It takes a bit of work but it isn't too bad to access the flaps. You have to remove the radio, ashtray HVAC controll unit and then the console. Definitely helps to go slowly, put things in baggies by groups, note and picture the little parts and pieces.

BTW, below the glove box is where the vaccum lines meet in a controlblock. You might want to find a legend for the vacuum system and then try testing each of the line going to the vacuum acutators. It sounds like one is open. You can also test your temperature control system once apart by re-attaching the HVAC controls.

On the otherhand, your car is a likely candidate for vaccum modulators. I would find diagrams and pictures so you know where the actuators are and possibly the test sequence that Mercedes has published. It is a bit lengthy but VERY thorough and leads you directly to problems and their repairs.

Good luck, keep us posted,

Haasman

[dkveuro]

Thanx.......I'm going to subscribe to......
http://www.startekinfo.com/StarTek/index.jsp

My 3 Official 124 manuals do not cover a/c system .


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