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dmtinker 11-25-2006 10:28 AM

blower motor testing 1982 300SD
Is there a way to test a blower motor? I replaced the ACC and it worked for 2 days. I heard a chirp then nothing. I suspect the motor is frozen but I don't know how to test it.

Could it be another bad ACC? Could it be a relay? There are no bad fuses.

Brian Carlton 11-25-2006 10:42 AM

Drop the passenger kick panel and you'll see the plug for the blower motor. Disconnect the plug, apply 12V and ground and see if the motor runs.....

If not, then you'll need to pull the motor.

If the motor is OK, then you've got a problem with either the controller, the temp switch, the resistors, or the CCU itself. It's more difficult to track these down.

dmtinker 11-25-2006 11:35 AM

Does it matter how many amps I apply? i.e. should I use a car battery or can I use something smaller?

Brian Carlton 11-25-2006 12:19 PM


Originally Posted by dmtinker (Post 1339558)
Does it matter how many amps I apply? i.e. should I use a car battery or can I use something smaller?

You provide the voltage. The device determines the amperage based upon it's resistance.

You can connect it up to the power station..........if they had 12V DC.......;)

sixto 11-25-2006 01:10 PM

With a motor that works intermittently, check how much axial play there is in the shaft. Usually you remove the motor, lay it on its side and it works. You put in in the car and it doesn't. That suggets worn bearings messing with brush alignment.

93 300SD

RAYMOND485 11-25-2006 06:41 PM

Blower Motor
1984 300d Turbo 141,000
Pull Power Plug And Check For 12 Volts, If 12 Volts, Replace MoTOR
Or Take It To Auto Electical Shop, Need New Brushes .

chosenberg 11-26-2006 02:12 AM

I had a blower motor that wasn't working. Usually if the fuse is fine, the blower motor itself is the most likely problem. I put a new one in today actually, and it works great ( Cold AC ). Its easy to install. First you remove the ashtray, then the radio, then the panel. If you want to test it you have to remove all those things, and take it out. Remove the wiring harnesses, and apply power to them. If it comes on, that means the blower motor itself is faulty and needs to be replaced (to much resistance). Another name for the blower motor is called the climate control unit, and can be purchased used from $75 to $100.

Rayh 11-29-2006 09:34 PM

blower motor current is about 15 amps
re: 83 300SD

I have two blower motors apart and can run them on a 25 Amp power supply I have on my bench.

They draw about 15 to 20 amps according to my fairly accurate ammeter.

If you can find a 1-2 ohm 25 watt resistor to put in series with the blower, you can temporarily drop the amps draw to around 5 to 10 amps...

I believe that the blower regulator/resistor does that function in the car itself, but I am no technician regarding this setup. :silly:

A charged car battery will work in place if a power supply for testing out the blower.

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