How can I fix my 560SL heater ??? - PeachParts Mercedes-Benz Forum

carlover · #1 11-25-2006, 10:39 AM

I usually keep the temp control on economy. As the engine heats up hot air comes out of the outside dash vents and gets hotter as the car warms up. So far, so good. Here's where it confuses me. After a few minutes of hot air, it starts getting cooler until it gets too cool for comfort. Let the car sit for a couple of hours, start it and cool air again. Let it sit overnight, start it and as the engine warms up, hot air for a while,then it cools off again. I can adjust the dial inside for a hotter/cooler temp, but it just seems to either keep the hot air coming in a little longer or a little shorter period of time. It doesn't "level off" and keep the car at a set temprature. It's either hot air of cool air--nothing in between. Any suggestions ?

david s poole · #2 11-25-2006, 10:53 AM

either the heater valve needs a new solenoid[because the diaphram is broken] or the temperature regulator relay pack is defective[hidden behind the glove box].

Gilly · #3 11-25-2006, 04:19 PM

One main cause for fluctuating temps is a problem with the in-car temp sensor, either the sensor itself or the aspirator (assuming the 107 has an aspirator, I believe the temp sensor is on top of the dash? Been awhile since I've been in a 107)
Gilly

ctaylor738 · #4 11-25-2006, 09:16 PM

There is also a foam tube that runs from the dash sensor to the blower cavity. This allows the blower motor to pull interior air past the sensor. The foam goes away with time and the temp relay gets a bad signal from the sensor. You can replace the foam tube with the Mercedes part, or get some pipe insulation at Home Despot. IIRC, access is by removing the glove box and passenger side under-dash panel.