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Wtf blower quit

K5Jimmy

K5Jimmy

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89 Jimmy the blower motor quit. The motor itself is maybe 2yrs old. Fuses are good. There is no power on the purple (motor) wire in any switch position. I replaced the relay and I have looked for voltage on all pins in all switch positions. I do have 12 volts to the relay on the red (straight hot) to the relay. I tried to jumper the resistor plug and looked for any voltage on any of the plugs. I pulled the dash apart and checked the switch and jumpered the plug. For each step I checked for any voltage at each plug, motor, checked the under dash wiring for possible rodent damage, and the chilton manual wiring diagrams are minimal help.

I'm using a Fluke to check all this stuff and I have refreshed all grounds. I jumpered the pressure switch at the ac. I will replace the resistor when it comes in tomorrow. Help....I'm either overlooking something, or I've looked at it enough that I've blinded myself.
 
K5Jimmy said:
89 Jimmy the blower motor quit. The motor itself is maybe 2yrs old. Fuses are good. There is no power on the purple (motor) wire in any switch position. I replaced the relay and I have looked for voltage on all pins in all switch positions. I do have 12 volts to the relay on the red (straight hot) to the relay. I tried to jumper the resistor plug and looked for any voltage on any of the plugs. I pulled the dash apart and checked the switch and jumpered the plug. For each step I checked for any voltage at each plug, motor, checked the under dash wiring for possible rodent damage, and the chilton manual wiring diagrams are minimal help.

I'm using a Fluke to check all this stuff and I have refreshed all grounds. I jumpered the pressure switch at the ac. I will replace the resistor when it comes in tomorrow. Help....I'm either overlooking something, or I've looked at it enough that I've blinded myself.
Click to expand...

Link will take you to all the service manuals and wiring diagrams you will need. Chiltons/Haynes are near worthless unless you've never touched a wrench before.

http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1

Fuse on mine melted the panel, that was a fun fix. IIRC, power for the switch comes off the panel on the brown wire, and is hot in run(?).

Edit: As I understand, no power to the fan, even though you know at least high (the battery 12V feed) has voltage. I'd bet either the relay or the power to the heater switch. Buddy had the relay go bad, kind of a pricey/hard to find piece for some reason, at least at that time, for him.
 
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Check the resistance across the motor. Parts aren't what they used to be. 2 years old should be fine but it happens. At lest rule the motor out.
 
Not familiar with how the blower is connected but I can give you some basic guidelines. First, when you replaced the relay, did you use the same type that you pulled out? Then check for voltage starting at relay. Should have a 12V larger gauge wire and another 12V smaller gauge wire that’s used to energize the solenoid inside the relay, and a ground (check resistance from relay ground to chassis ground - should be 0 ohms). If all is good at the relay check the resistance of the resistor. Don’t know what it should be but if you have infinite resistance then it’s blown. Check the resistance of the blower motor, I’m guessing somewhere in the neighborhood of 20 maybe 30 ohms - but again if it’s infinite then a winding inside it is fried. Check the resistance of the switch selector from the 12V in to each individual switch selection - should be zero ohms. You can also check each wire for 0 resistance from the relay to switch and switch to motor (or however it’s connected) to make sure a wire isn’t broken inside the insulation that you can’t see.
 
Is the large red wire from battery junction block hot? It has no fuse as it is fed by fusible link from starter. Orange is hot with key thru switch. If red and orange are hot it would work in high. There is also a resistor in AC housing.
 
So far, 10g red from batt junction to relay is hot, no vdc anywhere else keyed or not. No vdc to switch with key on. 10.5ohm across motor. It got dark, and the wife started talking about some thing or another about either her sister, cousin, or somebody, so I just laid it all down for tonight.
 
K5Jimmy said:
So far, 10g red from batt junction to relay is hot, no vdc anywhere else keyed or not. No vdc to switch with key on. 10.5ohm across motor. It got dark, and the wife started talking about some thing or another about either her sister, cousin, or somebody, so I just laid it all down for tonight.
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So the relay only has one post that measures 12V? Need to trace the other wire back that should be reading 12V to see where that comes from.
If someone has the schematic handy to post it’d be easy to figure out. Otherwise I’ll try to find one later.
 
Maybe this will help
 

Attachments

  • blower.pdf
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I think @dyeager535 got it right in his edit.
I’ll be using the wire colors in the schematic posted by frankin5. First, since you measured a reasonable resistance for the blower motor I’ll assume it’s good for the time being. Also, since the motor doesn’t work even on high then the resistor pack is not at fault since it’s not even used on the high setting, so the problem is elsewhere. Let’s start off at square one again. Check for 12V on both sides of the fuse with the key in either the accessory or running position. If voltage is good then the brown wire goes to the selector switch through a connector (C235 in the schematic). Check the brown wire at the selector switch for 12V. If nothing then disconnect the connector and check for power at the connector. If the selector switch does have power then move the switch to a setting where the motor should operate and check the brown/white wire on the selector switch for power. Check all the settings. If no power on any settings then the switch is bad. If the brown/white wire does have power move on to the blower speed selection switch. Check the brown/white wire for power. If no power then the wire is bad. If it has power then check the orange wire for power (that’s the high speed setting). If no power then the problem is the speed selection switch.
That should cover everything up to the relay. My guess is the control selector switch is bad as dyeager mentioned. To check it (if you feel brave) you should be able to put a jumper from the brown to brown/white wires on the selection switch and turn the blower speed switch to high. Someone correct me if they think of a reason not to.
 
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Found it! I had blinded myself. The plug on the selector was loose and not making contact. I feel pretty dumb, but I know that when I get frustrated or pissed, I need to just walk away. I couldn't get the plug to snap, but it's on as tight as it will go. The keeper is deep enough to latch, but it won't snap. Tiny zip tie was a sumbitch, but that will work until it doesn't. I'm not a mechanic, I just work on shit.

Thanks to all who helped with links, clear thinking and suggestions. Feel free to point and laugh.
 
K5Jimmy said:
Found it! I had blinded myself. The plug on the selector was loose and not making contact. I feel pretty dumb, but I know that when I get frustrated or pissed, I need to just walk away. I couldn't get the plug to snap, but it's on as tight as it will go. The keeper is deep enough to latch, but it won't snap. Tiny zip tie was a sumbitch, but that will work until it doesn't. I'm not a mechanic, I just work on shit.

Thanks to all who helped with links, clear thinking and suggestions. Feel free to point and laugh.
Click to expand...
We’ve all been there. That’s why it’s good to bounce your ideas and problems off others. Glad to hear it’s fixed. :waytogo: At least now if it stops working again you’ll know the first thing to check.
 
Lol! Feeling dumb. We can laugh at that, but not melting like dyeager535, or worse. No laughing there. Glad you found it
 
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