89' 300E Blower fan stuck full on
 

Anyone know why the AC/Heater blower fan would go full on and not shut off when the ignition is turned on? All the climate controls seem to working. The fax controls do nothing.

sounds like the regulator is shot..... takes a couple of hours to do the first time... you have to take off the wiper...and a bunch of other stuff... but it's a very do-able job.

I did it about two years ago when I installed a new regulator, guess they don't last long.

[QUOTE=Netconn;3298780]I did it about two years ago when I installed a new regulator, guess they don't last long.[/QUOTe


yes, i guess if you buy cheaper ones (like I do) the risk is greater that they won't last...

the only other issue i can think of is your ignition switch. you can try backing off the key a millimeter after you start.... but your problem doesn't seem to be an ignition switch issue... but it is a no expense and no time trouble shoot

Try replacing the climate contol panel. Cheap fix Around $25 @ Junkyard.

There is a 3 terminal connector behind the brake booster that goes to the blower regulator. It has a heavy black and red wire and a lighter yellow wire. The yellow wire is the control signal for the regulator and varies from about 1 volt (low speed) to about 6 volts (high).
You can check voltages with a voltmeter or unplug the connector and remove the yellow wire and see if blower still is at max.
If you replaced the regulator 2 years ago with a quality replacement and it is gone again, then your blower might be drawing excessive current due to dry bushings or worn brushes and commutator.

The fan does squeak for a few seconds when it first starts up. I oiled it last time it was out, maybe I need to try a different oil then LPS. It's blowing hard so I know the bearings aren't sticking. I was going to meter the yellow wire as soon as I get a few minutes but I'm thinking it's the regulator again. It's not the expense as it is the work replacing it.. I think this time I'll make the modified W140 regulator.