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Can’t get fan blower to come on

Burt71gtx

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1996 gmc savana 1500 5.7
Can’t get blower to run , all fuses and relays are good, have 12 volts coming into blower resistor but no volts at connector to blower motor, brand new blower resistor from auto zone today, any help out there is appreciated, thank you
 
do you get anything at the blower when on high? the high bypasses the resistor completely and goes though a relay direct to the blower motor. most of us have to at some point install an extra ground strap from the blower to the body somewhere.

also follow the positive wire from the blower up into the dash. some rigs have a connector behind the glove box that gets melty over time and looses connection. I had to clip mine out and wire it direct eliminating that connector.
 
You said power into the relay - what about power out? Your gonna need to chase the harness. Did you backprobe the supply side of the connection to the blower for power? If it’s dead supply power there to see if the blower works. That would indicate an open circuit between relay and connector.

Power the blower with a jumper- does it work?


This is really where a powerprobe shines.
 
iirc all power runs through the blower switch in the dash, then to the resistor for all speeds except for high. the high on the switch goes direct to the single relay sitting on top of the air box mounted near the resistor. another power wire from the fuse box goes to that relay and out to the blower motor. the power wires from the switch for the lower speeds go into the resistor where one single wire comes out tying into the same wire going to the motor. 9 times out of 10 when you loose all speeds including high, it's a connection behind the dash controls where power comes into the blower switch. the pins in those connectors get hot and crispy creating a bad connection over the years of use. This happens mainly due to a blower motor getting up in age with the bearings loosing oil among the motor winding going bad causing the motor it's self to pull more amperage than it did when new. the higher amp draw makes all the connections between the motor and the switch to create heat and begin to self destruct.

a new blower motor on high will pull around 16-20 amps, that is a heavy load for the small wires in the dash to handle. couple that with tiny connectors that GM put in there makes things even worse. I would almost guarantee if you pull the control panel from the dash and begin to disconnect the connectors one by one starting with the blower switch, you will find at least one connector with a burnt crusty terminal somewhere along the way towards the resistor/relay and blower.
 
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