97 E320 Heater blower stays on..key off
 

I just bought a 97 E320 and the heater blower stays on always. Key on or off I can't turn the @#@$ thing off! Had to pull the blower connector as to not drain the battery! Climate control display appears to be functioning but changing fan speed does nothing...fan stays on high. Any help would be appreciated.

Make sure the REST button is not activated, it will recirculate the heat in the car with the engine off. It is described in the owners manual.

No response when pushing the rest button...and no blower adjustment still.

Blower motor regulator

Gilly

RF FOOTWELL, PANEL OFF, CHECK FOR CONSTANT POWER TO BLOWER REGULATOR, MAKE SURE "REST" IS OFF, IF POWER REMAINS AT REGULATOR CONNECTOR, PROBLEM IS MOST LIKELY ACC PUSHBUTTON UNIT. REMOVE UNIT (USE RADIO KEYS), UNPLUG UNIT. IF BLOWER STOPS PROBLEM IS MOST LIKLEY ACC UNIT. EXPENSIVE PIECE, APPROX. $1000.00. SORRY, I DO NOT HAVE TIME TO CHECK WIRING DIAGRAM. YOUR BEST BET IS TO BRING IT TO SOMEONE QUALIFIED TO DIAGNOSE. THERE IS A MINOR POSSIBILITY OF THERE BEING A SHORT IN THE WIRING HARNESS. (MAYBE THIS IS THE REASON WHY THE PREVIOUS OWNER SOLD THE CAR.)

Unplugged the acc unit and still blows, I did round up a diagram and it appears that there is constant 12v to the motor and it gets ground from the regulator. Unfortunately, there is an updated regulator which requires an updated motor and mounting plate. I guess I'll make sure its the regulator and try to find a good used one.
Thanks for the help

Yes, that's correct, the blower motor gets a constant battery power supply so that the REST function will work. I don't think many people use it BUT that's beside the point.
The blower regulator is kind of common. You can research it if you want, I'm sure there is a published test for the regulator somewhere. You've already disconnected the climate control panel, seems like a no-brainer to me, but it's alot of money to replace the whole thing (you are correct about the neccesary update-need a new motor and regulator, the plastic panel that allows you to access the motor, and I think you also need an adapter harness).

Gilly

I use it all winter!!

I met a W210 owner on another forum with the same problem, and he solved it with the updated blower regulator, blower, and so on. The repair was close to $800CDN at a Mercedes dealer.

I used it once (below 0 Deg. F temp.) and decided not to use it again mainly because it brought the engine temperature down quickly. Without using the rest the engine temperature stays near the operating temperature. When I restart the car 15 minutes later the car blows hot air immediately.

John, I didn't say "no one" uses it, I think a very small percentage of people use it. A small percentage may equal several thousand people, so maybe that runs counter to saying "not many people". There are probably a higher percentage of people who visit this site that may use it, because we are the type who are more "in step" with their vehicles. But the average MB owner probably doesn't even realize that it's there or what it does.

Gilly

I agree. I stand by my original statement, exclaiming that I use it.