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Please explain HVAC system

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Old Feb 19, 2013 | 03:51 PM
  #1  
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Default Please explain HVAC system

I have an 81.

I replaced all the HVAC stuff including:
fan
blower switch
blower relay
blower voltage regulater on air box
All vacuum lines
All vacuum pods
vacuum switch
and more

I believe the system is not working correctly. I don't know what else to replace.

The low speed fan comes on when the ignition is on. I know this is normal.

But shouldn't the med/high come on when you move the switch? even if the engine isn't running? Mine stays on low. If I fold the brown wire on the voltage regulator on the air box, the low speed stops and nothing runs.

Any sort of advice on this?
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Old Feb 19, 2013 | 04:40 PM
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How about the blower motor resistor, older vehicles use them not sure about 81 ?
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Old Feb 19, 2013 | 05:54 PM
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I believe he is calling the blower motor resistor a voltage regulator.
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Old Feb 19, 2013 | 06:06 PM
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If you fold-over a wire and the fan stops...sounds like you have a broken wire...inside the insulation. Time to check continunity on the fan motor wires.
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Old Feb 19, 2013 | 07:01 PM
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Originally Posted by '75
I believe he is calling the blower motor resistor a voltage regulator.
Yes, that is my bad.....first the memory, then the legs
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Old Feb 19, 2013 | 09:09 PM
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Originally Posted by commander_47
I have an 81.

I replaced all the HVAC stuff including:
fan
blower switch
blower relay
blower voltage regulater on air box
All vacuum lines
All vacuum pods
vacuum switch
and more

I believe the system is not working correctly. I don't know what else to replace.

The low speed fan comes on when the ignition is on. I know this is normal.

But shouldn't the med/high come on when you move the switch? even if the engine isn't running? Mine stays on low. If I fold the brown wire on the voltage regulator on the air box, the low speed stops and nothing runs.

Any sort of advice on this?
With the ignition in the run position all speeds should work. Check for voltage at the high speed blower relay, if no voltage at relay check for voltage at the speed selector switch in the console
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