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1995 GMC Suburban Rear a/c-heat blower

S

smmorris

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Concord, NC
I have a 1995 GMC Suburban. The rear HVAC blower motor started running continuously and I unplugged the wires that go to the motor to prevent the battery from running down. I could usually plug it back in later and it would be fine. I considered putting a switch on that wire but before I could it quit running at all. I tore open that area so I could access the 3 relays in the back and replaced all of them with new ones. Nothing changed, the motor still will not run at all. I pulled the resistor from the underside of the duct between the blower and the coil. It looks fine but there is current running to it at all. The meter shows no current running to the motor on any of the 3 speeds. I can hear each of the 3 relays click when I change the motor speed switch on both the front and back seat controls. I get no current on any of the heavy wires running to the relays. There is a heavy black and red pair of wires coming from beneath the head liner down to the relays. I unplugged it and got no current on either end. It seems that there is no power coming from the front of the vehicle. I have checked all the fuses in the panel and under the hood. I am not sure what to check next. I would really appreciate any suggestions and guidance that can be offered.
 
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Check the connector under the glove box for melting down. Then check the control head up front for the rear HVAC and see if there is power there. next check the main HVAC control head for a bad blower switch, the switch controls AC on off in addition to the blower.
 
Thanks! I will check those control head switches. There is a connector under the glove compartment that gets super hot. If you wiggle it the front blower goes on & off. It appears to be an inline connector and I had wondered if it would make a difference if I cut the connector out and spliced and taped it.
 
smmorris said:
Thanks! I will check those control head switches. There is a connector under the glove compartment that gets super hot. If you wiggle it the front blower goes on & off. It appears to be an inline connector and I had wondered if it would make a difference if I cut the connector out and spliced and taped it.
Click to expand...

Replace the high current draw front blower motor. Motor has started to short out and is pulling too much current. Add a ground strap from the blower motor to the dash bar or other good ground. Solder the wires as crimps will melt later.
 
Are you saying that I should totally replace the front blower motor? Would that be related at all to the problem with the "rear" blower motor? I appreciate your help!
 
Sorry, read it more carefully. Got the part about "Motor has started to short out and is pulling too much current." I get overly excited at solutions :)
 
I checked the control heads, all three of them, control for rear on roof in front seat, control for rear on roof in back seat and main control in dash. Removed radio to access wires. Everything seemed to check OK. Could hear relays in back clicking at appropriate times. Cut the bad connector for the front blower out and spliced the wires,(thought that might be the hot feed for front and back) front blower works great and the splice is not heating up, the connector was really bad, melted etc. Checked voltage at back blower and still nothing. The heavy pair of red & black wires coming from headliner showed no voltage. The black wire checked continuity with ground. The red wire showed nothing. I stripped back a section of the red wire and connected my jumper cable to positive on the battery. I touched the other "hot +" end of the jumper cable to the bare section (where I had cut back the insulation) of the red wire and the blower fired up. Everything works perfectly. Both front and rear controls turn the blower on & off and change the speeds and everything turns off when I turn the ignition off. Do you think I am safe to run a permanent hot wire to the rear and cut the old red wire loose?
 
Sounds like you have found a bad wire. New hot wire is fine, just make sure it has a breaker or fuse on it. I suggest a 30A breaker and make sure the wire is rated as such.

Replacing the melted connector will buy you some time before the front blower motor running on high turns the crimp connectors brown from heat. The wires and this connector is barley large enough to handle the HVAC load. A dragging blower motor will take this connector out - been there done that. Replaced the connector a second time with a new blower motor and not melted since.
 
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