'99 Mercury Grand Marquis, heater problem?

billr

wrench
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Make
Mercury
Model
Grand Marquis
Year
1999
Miles
unk
Engine
4.6l V-8
This is a friend's car, says whenever the cabin blower is turned on the system voltage quickly drops, to the point that the engine will soon die; he is observing the voltage drop on the dash V gauge. Anybody have schematics of the heater and A/C circuit so I can offer him a guess?
 

grcauto

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Here's a diagram. The blower module may be shorted internally.DSC_0011.JPG
 

billr

wrench
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Thanks, that should be enough to guide him in checking.
 
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