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Old 11-08-2010, 11:32 AM
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no power at heater switch

i replaced the blower motor, 2 new relays to make sure they both work. hi, low resistor is intact. i have 12 volts to relay, but 0v at hi low switch. ive checked every ground and wire as well. ive checked ewvery fuse with a test light and by taking them all out one at a time. any ideas? how does this circuit work anyways?

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Old 11-08-2010, 11:47 AM
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Quote:
Originally Posted by jls4speed
i replaced the blower motor, 2 new relays to make sure they both work. hi, low resistor is intact. i have 12 volts to relay, but 0v at hi low switch. ive checked every ground and wire as well. ive checked ewvery fuse with a test light and by taking them all out one at a time. any ideas? how does this circuit work anyways?
Perhaps you could tell us the year/make/model? The mind reading thing still isn't working that well.
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Old 11-08-2010, 11:48 AM
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its a 1985 monte carlo ss. i also failed to mention that it did work before, and has always worked, up until now
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Old 11-08-2010, 03:10 PM
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Referring to the attached diagram the blower switch and the resistors are fed by a fused ignition source.
This diagram shows the blower motor running in LOW speed at all times when ignition is ON by connecting the (2) resistors in series with the motor.
When the switch is in the MED position only one resistor is in series with the motor.
When the switch is in the HI position the resistors are not in the circuit and the motor receives full voltage.
The system does not use relays.

vicrod
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File Type: pdf GM heater fan wiring .pdf (281.2 KB, 65 views)
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Old 11-08-2010, 03:33 PM
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im sure the system uses a relay. the relay is located right next to the blower motor. its also brand new and tested to see that it works.12v comes into the relay. next to that HOT wire there is black purple lt blue and brown( off the top of my head.) it grounds under the dash above the computer. at the hi/lo switch it is 4 wires. mind u not one goes to the fuse block. ive also jumped the motor itself and it runs mint. im scraching my head too, its been a night mare to figure out and its 25 degrees outside.
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Old 11-08-2010, 04:12 PM
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I checked (2) different sources of GM diagrams and neither show a relay.
I do see that there is radio noise suppression device but that won't effect the system operation.
It is possible that the relay was added for some other reason but it's not stock.
Send a diagram of what you have.
Stock setup is;
1- brown wire from fuse block ignition ON to blower switch and resistors.
2- yellow to resistors for low speed.
3- lt. blue to resistors for med. speed.
4- orange direct to motor for high speed.

What is connected to the coil of the relay on terminals 85 and 86?
Is the motor grounded?

vicrod
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Old 11-08-2010, 05:17 PM
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Brown @ resistor is hot with ign on .tan is M1 .lt blue is M2 @ resistor .
Dark blue from resistor to high speed relay N/C .
Red on N/O of relay ,always energized [has a fuse link in it somewhere , look by the starter or battery ???]
Purple to motor .
Orange to high on fan switch .
Br/Wht from fan switch to A/C control .
Brn from A/C control to fuse block .
Black from relay and fan motor to ground .
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Old 11-08-2010, 05:29 PM
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The heat only (no A/C diagram) does not show to use a high blower relay. The A/C equipt diagram does show a hi blower relay, so go with what you know. If you have no power up to the control then suspect the connection on the bussbar in the fuse block. If no power at the resistor then suspect the blower switch in the control head.Brn / white from the HVAC control head is the power to the blower resistor.The green/black goes to the A/C side of the system.
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Old 11-08-2010, 06:17 PM
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i cant post the image i need 2 for some reason. i went into paint and pulled op a pic of the relay and color coded and mapped out whats what and what goes to where. how can i send it to the thread so everyone can see? can i just email it even?
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Old 11-08-2010, 06:27 PM
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at the back of the switch 4 wires come out- brown, light blue, tan, and orange. they all go to the blower resistor (which is the thing with the 3 coil looking things) none of these wires go to the fuse block. theres 12 volts at the redwire going to relay. i need to send the picture i took so u guys can see
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Old 11-08-2010, 06:27 PM
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at the back of the switch 4 wires come out- brown, light blue, tan, and orange. they all go to the blower resistor (which is the thing with the 3 coil looking things) none of these wires go to the fuse block. theres 12 volts at the red wire going to relay. i need to send the picture i took so u guys can see
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