ceevettefly

What elimination procedure do I go through to find out why my heater /air conditioner blower stopped working, not completely would work sometimes but now it doesn't work at all

Nowhere Man

start with the fuses

Benny42

Tell us more about the car. Year model would help some and if its standard a/c or electronic climate control. Fill out your profile.

Cliff Harris

What fuses? The power for the blower motor comes from a fusible link on the starter solenoid.

Check for 12 volts on the resistor/blower control module red wire. That wire comes from the fusible link.

ceevettefly

If it's the red wire on the plug that goes on to the housing top near the firewall because I did test that one and there is power

vetteboy88

just went through this. There are a couple of useful guides I got off this forum. Mine turned out to be the module with two plugs that fits into the evap box right near the heater core on the firewall. Pricey part, but available used on ebay, etc. Easy fix, especially with the forum help!!!

JWMorrisey

The red wire coming off the batter <+> is for high blower only and feeds the blower motor relay. The blower speeds are fused off the AIR COND fuse in the fuse box (25Amp)


Model year and manual or electronic A.C. would be most helpful.


A blown fuse link coming off the battery causes loss of high blower speed only. A blown fuse or a failed switch (or relay) cause loss of every speed except high.




My '86 just went through this where I lost all blower speeds but high.




Hope this helps.
Jonathan.....

ceevettefly

1987 coupe Z52 automatic , electronic climate control ...I entered this information on my profile

JWMorrisey

Do you have the FSM?


I'm sitting here looking at the '86 FSM ('87 should be similar) and it shows four (4) wires into the solid state blower motor control.

RED wire 12v from the fusible link ( IIRC, you have already ck'd the voltage here.

BLACK wire Chassis ground. Also ties into the chassis ground for the blower motor. Do a DVOM check between the RED wire and this wire.

BROWN wire Signal from the control head to operate the various speeds. Key ON, control head in AUTO and fan in full-UP for 10sec. Should see 5.5v here

BLACK/RED wire Power feed to the blower motor. A red wire comes off this circuit back to the control head to provide feedback that the blower motor is actually working. It contains a 5amp underhood fuse that may be blown. The book says it's near the blower motor, prob'ly a inline fuse holder.


Hope this helps a bit.
Jonathan.....

ceevettefly

87 has six out of blower control a 4 prong and a two prong
tried other module from another car blower went to full speed
and would not turn off even with key off ....after checking I
believe I need fan control module .. ordered will be here tomorrow
will let you know the result

SJPMLT4

My blower works for the floor outlets but the dashboard ones do not. Does anyone know how to fix that?