Correct 300e Blower Motor Diagnosis?

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Chip L - 11 Jul 2005 17:03 GMT

Would appreciate what you think of this troubleshooting and diagosis.

'92 300TE w/ 142k miles. Blower Motor totally out - all levels.

1. Checked voltages at Blower Motor Regulator connector (located above
and behind the brake boost)

Yellow = 1v (low fan speed)
4.5v auto
9.5v high
Red 12v
black Ground

2. With power to the regulator looking OK, I check the blower motor.
Motor is OK

Red = hot (12 v).
Blue = not grounded. This is apparently the problem. grounding this
lead causes the fan to run very high.

3. Diagnosis: Blower Relay. My reservation is that I thought the fan
would blow constantly on high with a failed Blower Relay.

Thoughts?

Chip L

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Thom - 13 Jul 2005 19:08 GMT

Wow, got the same problem, but I get no voltage at the
Regulator/firewall plug. I even swapped the control panel out with a
new one, along with replacing the fan motor and regulator.

I just found that there is a relay??? that controls, among other
things, the climate control fan?

i.e. "RELAY
86-9/89 124.030 - up to A 820021
Seat Adjustment
Auxiliary Fan
Window Regulator
Ventilation Control-2-step
10/89-92 124.030 - from A 820022
5-Pins - ALU Casing
Ice Cube
Increase in Shift Point
Burglary Alarm Systems"

I would be interested to know where this is, and if anyone has ever
heard of this relay failing for only one of the 5 things it controls,
rather than blowing for everything.

Thom
1989 300E, 243,000 mles

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