I work on Cars on the side and have a 98 E320 that is throwing me off. The car was bought in terrible condition and I am slowly getting it back in order. The latest is the blower failure. The fan would come on but would stay at a very low speed. It would show that it was increasing on the display but it would not go above low speed. I exposed the regulator and it was the old square style. The blower motor was squealing slightly as well so I suggested the upgrade to a new style blower and regulator. I ordered the parts aftermarket from Auto Parts Warehouse.

I installed them and the blower worked great with one exception. When I turned the ac push button panel off, the blower remained on at a very slow speed. You cannot feel airflow or hear it when the engine is running. When you turn off the car, the fan runs for a few seconds and then shuts off with a click ( sounds like a relay). I called and requested a new regulator as this one would not shut off when manually turned off. I let the car go and received a call about a half hour later saying the blower was on high and would not shut off after minutes of the car being off and the key out. They unplugged the assembly when they got out of the car.

New part came in, car came back today, blower stays on when plugged in. I replaced regulator and all is well with one exception. When I turn it off, it still runs very slowly but shuts off after a second of key off. Same as before. I ran it at all speeds, started and stopped vehicle, works great with exception of still running with key on acc off. I tested resistance between the spade terminal ground and the ground pole on the plug and show around 80ohms when turned off. The one that was always wide open was around 5-10 ohms.

I let the car go and they called and said the fan only worked on low speed for a while, then revved up and now it won't shut off again.

Anyone have any ideas?

 

Mb changed the regulator style from three block style to the larger pointy style. The blower motor has to be replaced unless you order the 140 regulator and splice the wires together. I believe the regulator was necessary because my reference voltage was moving but I was getting no change in ground control through my old regulator. I have replaced this combo back in my dealership days but it was always woth MB parts. I'm thinking that the ACC module may be acting up but I'm not 100% on the voltage that should be at the low voltage input when the fan is off. I would also assume that with it off, I should have OL on the ground through the regulator when fan demand is zero instead of 80 ohms.

 

I meant THE block style, not THREE block style regulator. Does anyone know what the signal voltage should be with the ac panel off? I would imagine zero. I won't have the car back til Monday or else I'd be wrapped up in it right now until it was fixed. I miss having access to all the wiring diagrams.

 

I had the same problems with my 1996, replaced the regulator, blower continued to run aftrer turn off ignition, I think the last thing I did which corrected the problem was unplug the climate control unit and plugged it back in, its been working fine, that was 6 months ago.

 

I ended up testing all of the wiring again and it showed a bad regulator. I ordered a behr from MB and it ha worked like a champ ever since. You get what you pay for.