With the key on i am getting power to the BM.I pulled the two wires off the BM and put 12v to the motor and it works fine.Confused.

What is the black thing called behind the regulator where the two wires from the BM come from? Does it control the amount of volts to the BM?

Sounds like a bad regulator to me. They're basicly a heavy duty FET. They can fail so that they will show voltage at the load but not supply any current.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

This is a very expensive part. How can i be sure that it is bad?

http://catalog.peachparts.com/ShopByVehicle.epc?q=1989-Mb-4--0sel-Climate--Control&yearid=1989%40%401989&makeid=MB%40%40MB%40%40X&modelid=420%2DSEL%2D001%40%40420SEL&catid=R%40%40Climate+Control&subcatid=R2022@@Blower+Regulator&mode=PA

See the red and blu wires that goes to the blower??
Jumper wire from the blu to ground ..if that gives you high fan, reg is suspect.
But you see that 3 wire plug?..that should have a yellow wire that is variable V from ther Control Panel..that is what triggers the regulator and if no V there , the problem is not the reg.
You should have 12V ay the red also.

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A Dalton

I will test it tomorrow.

I don't even know what the problem is yet.

When I say to jumper the blu wire to ground, I am not saying to unplug that wire and take it to ground. You place a jumper on that wire and ground the jumper. That by-passes the Reg.
If the fan does not turn when you do that, then test the red wire for 12v at the BM.
If it still does not work, spin the fan blades at the same time .
Grounding the blu wire is the same as bringing 12V direct to the fan motor ..if NO, then the BM is faulty.

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A Dalton

With both wires connected to the BM and jump blue wire to ground the BM runs at hi. speed.I also get 12v at the red wire.Sorry i misunderstood you.

>

I knew that, so I re-worded it.
Anyway, that eliminates the BM and points to the Regulator.
But , before changing that, make sure you have the Var V at that third wire, as that is what triggers the Reg.

I mention that wire as yellow, but it may be a different color b/c I do not have the schematic for your model. The 124 uses yellow.

That 3 wire feed plug should have a ground, [ neg] a 12V Hot [pos+] and the third will be the Var V from the Control Panel.

If you have 12 V from the plug pos and ground and Var V on the other wire
and ground..then you need a regulator.

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A Dalton

New test confermed i need a regulator.Thanks Arthur and every one for all of your help.