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Old 08-15-2007, 06:50 PM
TheWagner
 
Join Date: May 2007
Location: Maine
Posts: 5
Excessive Heat from Dashboard in '85 500SEL

I have a question for those here with much more experience than I. I have recently acquired an '85 500SEL for a good price and have set about making it driveable: new fuel lines, new rear brake line, new bilsteins all around, an oil change, belt tightening etc. I have driven the car a little over 5k miles and have noticed nothing but smoothness EXCEPT for loads of heat coming out of the Dash/center console.

Like many old 126 s-class's my acc unit seems to be inoperative. It only blows hot air no matter what. I think the problem is the mono-valve is shot and the a/c is not charged/leaking etc--I am content to drive with the windows open for now. The problem is the heat coming through the center console makes the radio so hot that it malfunctions, spits out the tape adapter for my iPod, and then clicks on and off for a few minutes. I find that opening the ashtray lets some heat out (into the cabin ) and prolongs the time I can use the stereo/tape adapter. The heat under the drivers side near the pedals is also very hot, as I found out on a recent jaunt across Indiana, Ohio, and Pennsylvania in sandals.

My question is, where the heat coming from (duh the engine?)? and how can I mitigate it? Is it there because I am not using the acc system? would getting the a/c running get rid of the heat?

What say you, O forum?

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  #2  
Old 08-15-2007, 09:36 PM
wscheffer's Avatar
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Join Date: Jun 2007
Location: Ohio
Posts: 108
Did you try pressing O to turn the system off?

If the mono valve is not working correctly then turning on the A/C would have no affect.

I have heard of people removing the hot water hose going into the mono valve and stuffing it with a rag to slow down and stop the flow of hot water getting to the heater core. This may make it tolerable till you can fix the mono valve.

Hope This Helps!
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  #3  
Old 08-15-2007, 11:51 PM
cdplayer's Avatar
Just my Jeep and my S500
 
Join Date: Aug 2006
Location: Sacramento, Calif.
Posts: 581
cdplayer

Not sure but the '85 should probably have 3 "slide" levers under the center vent. Use these to shut off the air flow. I have an '84 so I think the dash set up is similar. Also with mine the center vent will be a problem if the lever becomes detached from the flap. Look carefully using a flashlight if you need to through the "gills"of the center vent. Move the slide lever back and forth to see if the flap does indeed operate properly.
If the lever has become detached(through road vibration and time) remove the glove box to ease in reattaching the rod from the lever to the flap. I was only able to remove the center vent gills by pushing them into the dash and out through the glove box opening.

As a precaution, too, be sure to thouroughly clean the space under the brake booster. Over time debris will collect here and the heat given off by the blower motor resistor unit will set off a fire. Believe me...I know. Fortunately for me my car was idling in my driveway with the hood up when my fire started. Just a thought, check the condition(cold) of the crossover exhaust pipe you see at the back of the engine as you look down on the driverside. Probably reaching here but if the pipe has a hole in it toward the firewall....hope not though.
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  #4  
Old 08-16-2007, 12:54 PM
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Join Date: Sep 2004
Location: DFW / Collin County Texas
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Clamp the hoses to the monovalve to interrupt the flow of coolant and see if the heat stops.
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  #5  
Old 08-19-2007, 11:40 AM
TheWagner
 
Join Date: May 2007
Location: Maine
Posts: 5
heat not from vents, radiating from center console

I have the acc unit in the "O" position and leave it there because it does nothing but blow hot air in any other position. the heat is coming from behind the center console with the acc unit and radio and ash tray. It is not just some heat but hot enough to be painful--so closing the vents will not really help. I will try clamping the hose to the monovalve to see what happens and also clean out all the debris under the hood (a good idea anyway) and see what I can find.

I have to drive from Connecticut back to Minnesota this week and it would be nice to figure out how to get rid of this heat.

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