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1991 MB 300E - Heater and Power Antenna don't work

So, my '91 300E runs nicely once again. BUT...

First, no heat. All the switches on the heater panel seem to work; fan switches do their thing, center buttons and defrost switch seem okay, and rotator temperature control engages air-conditioner. But setting rotator control all the way into the red "hot" setting has no apparent effect. It kicked in once a few days ago when I drove it home from the shop, but now ... nada. Zilch. Possible causes? There doesn't seem to be a problem with the thermostat; engine temps indicate normal (just under 80 deg C) during normal driving.

Second, antenna mast doesn't extend with powered-up radio. I opened the trunk lid and pulled back the lining, and had someone else switch the radio on and off, and couldn't hear any motor actuation. So... replace? Repair? I know that the antenna is relatively easy to replace if necessary, but if there's another possible cause, it would be useful to know.

What say ye all?

Reply to
the real dgs
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the real dgs ha scritto:

From this side of the monitor I see no connection of the 2 problems... :-) The antenna might only be a little bit too dirty and though gripped. Gently try to help it open up and then lubricate with silicon spray at first and than using a minimum amount of white grease (aka grease for contacts). For the heating system... check if you have enough water in the circuit. A low level of liquid might empty the internal radiator of the heater, resulting in the symptoms you mention. If you already checked the level, adding more than 1 liter of liquid you might have air bubbles trapped in the circuit. But I don't know if there are any valves to help sort out air from the circuit. Sorry.

Reply to
Cordy

Cordy ha scritto:

I forgot: check fuse, too. There might be a specific one near the antenna motor or behind the radio, in the wiring.

Reply to
Cordy

Check fuse for both symptoms in your fuse box... remove it and inspect it. Replace as an experiment.

Reply to
Tiger

On 1/15/2009 6:23 AM Tiger ignored two million years of human evolution to write:

All fuses in fuse box are good.

Reply to
the real dgs

Check for power at the antenna... make sure blue wire has 12V... check the other wire and make sure there is 12V also when radio is on.

As for heater... Looks like your heater valve is bad.

Reply to
Tiger

Tiger wrote, On 01/20/2009 11:44 AM:

I suspect the antenna isn't getting power. Couldn't pull out the mast with the radio on.

Looking into that next, yes. Thanks.

Reply to
der gediegene dgs

Did you ever figure this out? I have the exact same problem, everything else seems to work perfectly. I do know that the previous owner of my car did a serious butcher job removing the radio before selling it to me, and she said that the heater worked before. I have gotten everything else to work properly except for the antenna and the heat. The fan works perfectly at all speeds and settings, just no heat. No movement or action from the antenna whatsoever. The condition of the rest of the vehicle leads me to believe that the problems are not mechanical; most likely electrical. Thermostat is brand new and car runs at perfect operating temp.

Reply to
zgustine

First thing to go is replace the heater monovalve... this part does go bad. It is also called heater control valve.

Second to check is make sure your aux water pump is working... this is an electrical pump.

Third of all, do yourself a favor, replace all the fuses in the fusebox... they are notorious for looking okay while it is not when you take it out. They corrode because of aluminum contacting copper terminals.

Reply to
Tiger

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