Blower fan in 88 works until engine is started

[davran]

Riddle me this. The blower fan in my 88 works fine on both speeds until I start the engine: then it stops blowing air: sometimes. Turn off engine and fan works again.

???

Thanks,

[davran]

To be clear, the fan doesn't blow air when the key is in the off position. It does blow whe key is on, or on accessory, and usually stops blowing when engine is started.

[Greg S]

Is it somehow connected to the earth of your "IGN" warning light? I'd suggest tracing the source power for the fan, make sure it agrees with the wiring diagram, then the earth wires.

[LR01011000]

Sounds like symptoms of a bad ground....easiest test would be to run a temporary ground wire direct from the fan to the battery negative....

[davran]

Shall try all suggestions.

[davran]

The problem with Roddy's heater fan is the ignition switch; when I start the engine and the fan quits, if I turn the key back a bit towards 'off' -- but keep the engine running -- the fan starts. The 'fix' is repeatable.

WD40 has made the problem almost non-existent; my Mother, a devotee of the spray, would be so happy...