I'm a decent Shade Tree Mechanic, but just getting started on the electrical concepts side...

I want to test the used blower regulator that I just got before I tear iinto the car to install it. This part has a 6 month warranty, but I want to make sure it works beforehand.

Is there a test for it while before installantion?

Thanx

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03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather
90 300SEL 214k Pearl Black/ Alto Grey/Black Leather

Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio

does it look like a transistor with heat fins or heat sink?
only way to test her is to install intot he circuit, as there is a trigger wire to control the speed.
Unlike the old style using wire resistors to drop the voltage.
my 420 sel I just took a resistor box with perforated holes form a w123 and stuck her inside the air box, so air will cool off the resistors.
Running at med speed now, i have a 3 way switch so I can reg the speed to off, slow high.

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Mine does have the aluminum cooling fins attached.

Perhaps I can plug it in at it's intended electrical connection and read the voltage from the other end of the regulator?

What should the values be? (again novice with the electical stuff and a voltmeter)

Al

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03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather
90 300SEL 214k Pearl Black/ Alto Grey/Black Leather

Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio

I need to find this out also. My 92 300D fan runs on low all the time, i got a used reg and have noway to test. Any help would help us both.

I don't remember the actual voltage values.

However, plug the VR into it's three prong connector on the firewall. Ignition on, push button climate control unit (CCU) on low speed, voltage measured across red and blue will be small, let's say about 2-3 volts. Next, CCU high speed button pushed on, voltage maybe 8-10 volts (it will never be 12v).

If you want to play some more, CCU on auto, and as you vary the temp wheel, the measured voltage will vary as well.

No change in voltage measured at VR? Then do same tests on center prong of the three prong connector on firewall (the yellow lead of the VR connects to it). If those voltages vary, then bad VR. If those voltages don't change or is 0 volts, then bad CCU.

Briefly jump 12v directly to blower motor (repeat briefly)- it should roar to life if OK.

IMHO, Always replace the 30A strip fuse no matter what, and clean off the screw contacts as well.

the trigger wire send some signal to control the speed, only way to test is plug her in and pray it does all the necessary speed.
we all know electronics stuff either it works or nothing.

becareful as u cross the trigger wire with 12v, i dont know whether it could damage her.

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