Blower motor not working

DRILLER753

MEMBER
1997 CHEVROLET TRUCK
V8
4WD
AUTOMATIC
200,000 MILES

Blower motor stopped working (heater-a/c) bought new one (autozone) and replaced. Didnt work. Hooked 12 volt battery charger to old and new b.M. And they worked. Returned new b.M. And purchased blower motor resistor and replaced. Didnt work. Checked voltage 14.00v all settings. Checked voltage from battery charger 12.00v and hooked up directly to b.M. And it worked. Checked ground ok. Whats the problem? Im lost

3 Replies

JDL

MECHANIC
16,098 POSTS

I'd check the circuits at the high blower relay, go from there. 5.7L engine, not sure of litre size?

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Sunday, September 27th, 2009 AT 3:19 PM

DRILLER753

MEMBER
2 POSTS

I checked the continuity of the high blower relay(h.B.R) from contacts 85 and 86. The connector siide voltage from 87 and 87b to 86.13.5v. Pulled and checked fuse for h.B.R and voltage 12v. Everything good until underhood fuse/relay 50amp blower fuse good but no voltage. A/c relay good. Why am I not getting any voltage across slot? Its a 350 so 5.0 or 5.7 not sure.

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Sunday, September 27th, 2009 AT 6:26 PM

JDL

MECHANIC
16,098 POSTS

Orange wire is voltage for the coil side of relay, comes from the hvac control module. Black is ground. Purple carries voltage to blower motor. Dark blue is voltage for the lower speeds, comes from resistor. Red is voltage for high speed comes from 50 amp fuse, should be hot all the time. When the relay is not energized there is continuity for the lower speeds. When relay is energized only continuity for high speed.

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Monday, September 28th, 2009 AT 9:33 AM