95 Heat/AC issue
- Thread starter jham0077
- Start date
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SunlitComet
OBS Jedi-Do Good
yes. in simple terms you were testing it wrong. what you want to do is select the fan speed and test the output on the controller, make sure it gets thru the wire to the blower resistor and see if it comes back out in the "appropriate" voltage for the selected speed. that is where you stick the pos on the circuit being tested and the neg on body ground somewhere. you have a full diagram correct? what other diagnostic info do you have.
I followed this trouble shooting guide
http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/blower-motor-resistor-test-1#1
I have voltage at the resistor plug in the first 3 speeds. I have voltage at the blower when jumping the resistor connector. So I shold have varying voltage on the positive blower wire, depending on speed selected(with resistor plugged in and not jumped)? But I can't get it to work with its own ground plugged to it. I can run a ground from the battery, or even stick one to the dash support, and make the fan blow. It does nothing for the position selection though. I have diagrams of the controller wiring and ground locations.
http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/blower-motor-resistor-test-1#1
I have voltage at the resistor plug in the first 3 speeds. I have voltage at the blower when jumping the resistor connector. So I shold have varying voltage on the positive blower wire, depending on speed selected(with resistor plugged in and not jumped)? But I can't get it to work with its own ground plugged to it. I can run a ground from the battery, or even stick one to the dash support, and make the fan blow. It does nothing for the position selection though. I have diagrams of the controller wiring and ground locations.
SunlitComet
OBS Jedi-Do Good
is it possible the the ground or further downstream is broken?
I've checked the ground at the blower and blend doors to the back of the head and the battery itself. Meter beeps loud and clear. The one thing that's getting me is the diagram that I have shows a ground from the controller to a spot under the dash near the service connector. I can't find a ground under there anywhere.
So I piggy backed a ground from the battery into the back side of the ground for the blower motor and got everything to function. I didn't do this very long for fear of frying something. I got a smell from the resistor(it's out and hanging free). I heard a grindy-clicky kinda noise coming from the blend door by the accelerator pedal so I unplugged it. Even with the control unit in the off position, it made the noise. I'm assuming it's bad? Dead short? Just enough to not function properly but not blow a fuse? My diagram shows it's power fused separately but sharing a ground with the blower.
SunlitComet
OBS Jedi-Do Good
what resister?
The blower resistor that's mounted in the top of the housing. It put off a hot, dirty smell, kinda like the first time you turn a home furnace on in the fall. I replaced the blend door actuator but it did not affect the main issue.
I'm gonna chase the ground down and see if I can find the problem. If I can't find it easily, is there any harm in jumping another ground to that cicuit to make it work?
I'm gonna chase the ground down and see if I can find the problem. If I can't find it easily, is there any harm in jumping another ground to that cicuit to make it work?
SunlitComet
OBS Jedi-Do Good
DO NOT EVER run the blower power thru the resistor when it is removed. when installed it has airflow that flows across it to keep it from burning up, causing a fire and doing what you said. here is a breakdown of ground locations.
Yeah, I didn't let it run very long while it was out. I knew it would get pretty warm.
Found it. The main power/ground wires that feed the blend door and blower harness is roasted, the ground side of it is. I wonder if the bad actuator caused it. Maybe the pic works...
.
Found it. The main power/ground wires that feed the blend door and blower harness is roasted, the ground side of it is. I wonder if the bad actuator caused it. Maybe the pic works...
.
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