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Replaced blower motor resistor & control panel - still no fan on 95 c2500

G

gahammerle

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Help! Fan quit working on all 4 speeds. AC light & recirc light still light up and AC compressor clutch engages when turning fan on in AC mode, but not getting the fan to work. I replaced the blower motor resistor and the control unit with new parts from rockauto (ACDelco). I've checked the fuse in the dash fuse panel and it is good.

What is the next step? Bad blower motor? Is there a way to test that? IS there a relay somewhere? If so, is there a way to test it?
 
You should be able to run power direct to the motor, Gordy. It will only run in high, but if it doesn't run with direct power, it's hooped.
 
OK, I hooked a wire from positive battery post to terminal with the purple wire on the motor. Nothing. So I removed the motor and decided to hook both postive & negative directly to battery and whirling away it went right out of my hand. So I put the motor back in place and hook the purple positive back up and then ran a jumper from the negative terminal on the motor to a ground under the dash. Now I have the first 3 speeds working but the motor still doesn't blow on high. So my ground is bad. I couldn't tell where that ground wire leads to see if it worked its way loose. Anyone know where it leads?

I rarely ever run a fan on high so I won't miss it, but out of curiosity, why would the first 3 speeds work but not high? I put a new resistor in. Maybe I bent one of the wires on it and it is touching another now to cause high not to work? Does that make sense? I'm not about to pull that thing back out just to see - the back of my hand is beat up from the tight squeeze getting the old one out and new one in.
 
Well, another monkey wrench. :( It only blows hot air no matter what the settings even with AC engaged.
 
95 Suburban Heater control

Gordy, did you ever get this issue figured out? I have exactly the same problem. I have a new heater control unit, the resistor has been replaced recently as well as the blower motor. I have power in the purple wire except in high. The black ground wire has low power when I hook up a test light to it???? The fan runs good when direct power is hooked up.
 
Yes, sorry for not updating the thread. It started working properly the next time I used the truck. Not sure why it didn't work at first.
 
gahammerle said:
Yes, sorry for not updating the thread. It started working properly the next time I used the truck. Not sure why it didn't work at first.
Click to expand...

Usually on electronics when something is intermittent, it is a ground.

Some days I really hate grounds. Especially when you can not find them.
 
I'm not 100% sure if this is the exact location where the fan is grounded, but if you pull the glove box and the PCM, your going to see two wires on a ground point that is connected to the frame above the PCM. That might be it. You may want to consiered trying to squeeze a wire brush in there to clean it up then anti-ox it so there aren't any problems.
 
I'm back in business! I couldn't easily find where the ground wire led to and didn't feel like taking the time to tear the dash apart. I spliced into the blower motor ground wire and grounded it to the frame under the dash. Everything works properly now. Before, the ground wire was feeding back power from wherever it goes to. I wanted to fix it properly, but I needed the Suburban right away. Thanks guys for the help!
 
I found out that the relay controls the high speed part of the fan and the resistor coils control the lowers speeds. My wife complained of the the high speed not working. I swapped relays and presto....
 
blower motor resistor 1995 sliverado

can anyone tell me the exact location to the blower motor resister on my 95 silverado i need to replace it and i cant find it i took the glove box out but i still cant find it and posssible for a picture that would be greatly helpfull too thanks
 
sodo i have to take the dash off to get to it and if it is under the hood about where is t at cause i looked on the fireall on the passenger side and didnt see anything there
 
My blower motor spins when I hook 12v directly to it. When I have the key on, I have 12v power to the purple power wire in the first 3 settings, but the 4th setting gives me no power. What is this pointing to? Is the relay the square box on top of the air box that I cannot see the connection unless I remove it and the bracket?

I also have power to the ground wire through all four settings, as well as power to ground when the relay is unplugged. Where does the ground wire attach to the inside of the cab? I tried to follow it, but it seems to go into a harness and is wrapped to where it can't be seen.
 
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I think that sounds like the HVAC/FAN relay under the hood of the truck in the fuse box. When fan is on high the circuit bypasses the fan speed resistors and supplies 12 volts to the motor from this relay to the motor directly. That is my understanding from reading and looking at diagram for my 97.

Ground it out somewhere else close under the dash. Might clean the cab body to engine ground wire on the firewall. Or add another one to make sure its grounded good.

PM soon to follow.

Correction assuming 97 is same (probably is)...
Fan relay is as posted before on top of the duct work left of the resistors you can see both behind the glove box if you take it out.

The purple wire comes from the relay/resistors according to fan speed selected. The purple wire should have battery voltage ~ 12V when on hi. At low is might have 5V, M1 7 ish, and M2 9 ish volts. (note mine is not working and I think resistors are bad I get 11.9V on hi 11.73 v on all other speeds lo, m1, and m2.

Anyone ever measure what voltages are normal to speeds ?

I think my motor has gone bad as I get continuity to ground (touched dash brace to black wire) and get continuity. With the back wire hooked up I ran a jumper directly to the battery pos and attached it the purple wire terminal on the motor. The motor did not come on. So either my motor is dead shorted or something has gummed up the brushes or they are worn out. I had this happen on another truck once a dirt dobber or wasp was sucked through the duct work and ended up getting caught between the motor brushes and armature contacts.

Black wire is ground. If you take it off the wire should read negative or ground to the frame the same potential. If you have 12V potential to frame frome black wire then something is wrong. It goes back into the wire harness and spliced to common ground wire and grounds to the back RH of engine at intake (near where auto dipstick).
 
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