Hi Guys - I have a unit without air-con, it has two controls on the dash - one for each side of the cabin - blue at one end for cold, grading to solid red the other, with the TEMP markings 18, 20, 22, 24, 26 on each. Usually when these are set on a temp marking, you can hear a valve kicking in/out. Now there is no sound, even if set on MIN the heat is on MAX.

Could this be the sensor in the sunroof complex, or is the valve that's died??

Thanks

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1987 230TE (W124/M102) RH Drive 4-speed auto, 7 seater.
Some days you are the bug; some days you are the windshield

Well, like many of the faults I have had, many viewed, no-one made any suggestions, and I've solved it myself - but I still am willing to share my findings with you all.

I had originally checked the fuses and they seemed fine. However, when I removed the fuse that controls the heater water valve mechanism, and replaced it (even though it looked fine) - the system started working again - so my recommendation is to check fuses by changing them - not by just looking at them.

Maybe that's common sense, but there ya go!

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1987 230TE (W124/M102) RH Drive 4-speed auto, 7 seater.
Some days you are the bug; some days you are the windshield

Those ceramic "bullet" fuses are aluminum strips, and both corrode and fatigue crack. They often lose conductivity, and yes, loss of electrical power causes the heater valves to stay open all the time.

I'd get some good ceramic replacements (stay away from the plastic ones, they tend to "shrink" from heat) and replace all of them. A bit of dielectric grease won't hurt, either. Make sure the spring contact in the fusebox is clean for each fuse, too.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

... and often in an emergency when no fuses are available or you are trying to get an electrical item to work, simply rolling or rotating the fuse in its holder can often get a good enough contact.

As Peter pointed out, the aluminum fuses do corrode at both ends. Ideally, replace with the copper ones.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)