94 blazer ac blower fan control

[NHRA]

94 blazer ac fan will work on low and med but not high replaced resistor under hood but still no high speed fan?...........thanks

[NHRA]

Originally Posted by NHRA

94 blazer ac fan will work on low and med but not high replaced resistor under hood but still no high speed fan?...........thanks

im thinking there may be a high speed fuse? somewhere anyone know for sure..........cheers

[gmtech1]

High speed also used a high blower relay, that may be your problem. Or could be the switch itself, or a wiring issue between the two.

[j cAT]

Originally Posted by NHRA

im thinking there may be a high speed fuse? somewhere anyone know for sure..........cheers

check all fuses with a voltmeter power on.

since you have the lower speeds the only component that is changed when you go to max blower would be the high speed relay.

first find the high speed relay . then with the switch set to max blower speed see if you get voltage and ground at the relay coil #85/86 pins.

if so then check for voltage at #87/30 . if the voltage is not on both these pins of the relay then the wire or fuse /circuit is open that supplies power to the relay switching contacts.

as mentioned it is possible the switch at the max blower speed position is bad. I doubt it.

If the fuse is blown this may mean the blower motor is in need of replacement. remove blower and see if it rotates freely . bushings not worn or debris interfering with rotation. also wires shorted . fuse should be over 20 amps. I think !

[NHRA]

Originally Posted by j cAT

check all fuses with a voltmeter power on.

since you have the lower speeds the only component that is changed when you go to max blower would be the high speed relay.

first find the high speed relay . then with the switch set to max blower speed see if you get voltage and ground at the relay coil #85/86 pins.

if so then check for voltage at #87/30 . if the voltage is not on both these pins of the relay then the wire or fuse /circuit is open that supplies power to the relay switching contacts.

as mentioned it is possible the switch at the max blower speed position is bad. I doubt it.

If the fuse is blown this may mean the blower motor is in need of replacement. remove blower and see if it rotates freely . bushings not worn or debris interfering with rotation. also wires shorted . fuse should be over 20 amps. I think !

ok on the relay think there is like 8 pins one has a burnt mark the relay is for the blower motor i think about a 1 1/2 sq im going to relace that today...thanks everyone.....
yeah it #87 thats burnt...cant find a new one yet...............

[tg5398]

Where did you find the relay?

[NHRA]

got it at autozone, had to order it took 1 day and worked like a charm<<<<<<<

[tg5398]

Originally Posted by NHRA

got it at autozone, had to order it took 1 day and worked like a charm<<<<<<<

Sorry. I meant where on the truck did you find it?

[NHRA]

on mine its 94 and under the hood and its on the middle of the fire wall on a bracket one bolt holds it on
the relay has 5 wires and its about 2 1/2 in tall and like 1 in thick