rear air system blower fan won't turn on
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Cadillac Escalade, EXT and ESV Forum - 1999 - 2006 Discussion, rear air system blower fan won't turn on in Cadillac Escalade Forums; I posted about my rear air system issue in another thread, but wanted to pull this question out separately. My ...
  1. #1
    kentd is offline Cadillac Owners Member
    Automobile(s): 2004 Escalade ESV
    Join Date
    Sep 2011
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    9

    rear air system blower fan won't turn on

    I posted about my rear air system issue in another thread, but wanted to pull this question out separately.

    My issue is that the rear air system blower fan will not turn on. The hot/cold and ceiling floor actuators seem to be acting properly, although there is no way for me to be 100% as the blower fan is stuck off.

    My first thought was to replace the blower fan control module, which I did today with this part:

    Blower control module

    I swapped in this new part and this did not fix the problem. (I had earlier verified that the blower fan does operate if I apply 12V directly to it.)

    Now I am wondering where to turn next. I guess the next logical thing is to replace the rear hvac control module. I found this part:

    HVAC control module

    I have until tomorrow to pull the trigger on Amazon and still get Saturday delivery.

    I have two questions that I could use some help with before buying the control module:

    1) Is there any simple voltage meter debug I can do to ensure that the control module is the culprit?

    2) Has anyone else been down this same path and had success after replacing the control module?

    Fortunately the aftermarket prices on the parts isn't too much to stomach, but I do want to get this fixed sometime soon.

    Thanks,
    Kent

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  3. #2
    the cadillac man's Avatar
    the cadillac man is offline Cadillac Owners Master
    Automobile(s): 03 cadillac escalade
    Join Date
    Mar 2011
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    speedwell tn,
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    Quote Originally Posted by kentd
    I posted about my rear air system issue in another thread, but wanted to pull this question out separately.

    My issue is that the rear air system blower fan will not turn on. The hot/cold and ceiling floor actuators seem to be acting properly, although there is no way for me to be 100% as the blower fan is stuck off.

    My first thought was to replace the blower fan control module, which I did today with this part:

    Blower control module

    I swapped in this new part and this did not fix the problem. (I had earlier verified that the blower fan does operate if I apply 12V directly to it.)

    Now I am wondering where to turn next. I guess the next logical thing is to replace the rear hvac control module. I found this part:

    HVAC control module

    I have until tomorrow to pull the trigger on Amazon and still get Saturday delivery.

    I have two questions that I could use some help with before buying the control module:

    1) Is there any simple voltage meter debug I can do to ensure that the control module is the culprit?

    2) Has anyone else been down this same path and had success after replacing the control module?

    Fortunately the aftermarket prices on the parts isn't too much to stomach, but I do want to get this fixed sometime soon.

    Thanks,
    Kent
    Its worth a shot since it doesn't respond to the controls and the brain box(aka the control module) works the fan

  4. #3
    kentd is offline Cadillac Owners Member
    Automobile(s): 2004 Escalade ESV
    Join Date
    Sep 2011
    Posts
    9

    Re: rear air system blower fan won't turn on

    Sheesh! New HVAC control module failed to fix the problem.

    Tonight I broke out my Archer analog multimeter and went to work.

    In the end, here is what I found: The blower control module is not getting 12V from the battery as it should. Instead, I measured a measly 3V between the power and gnd (ORN and BLK) wires feeding the blower control module. This was with the blower control module harness not plugged in, so I know the blower control module is not at fault.

    Stepping back, I went to the underhood fuse box and pulled the RR HVAC fuse. I found 12V on the hot side of the RR HVAC fuse. Plugging the RR HVAC fuse back in halfway, I was able to probe both sides of the fuse and found 12V on each side.

    Next, I went to the back of the vehicle and found the power harness that feeds the blower control module. I unplugged it and measured the pins and found that it measured 3V at the power harness connector.

    So it looks like I have a problem with the power distribution to the rear blower control module.

    Has anyone run into this problem before?

    Here is the wiring diagram. Does anyone know how the RR HVAC power feed snakes through the vehicle? Somewhere in there is a 9V drop.
    Attached Images

  5. #4
    the cadillac man's Avatar
    the cadillac man is offline Cadillac Owners Master
    Automobile(s): 03 cadillac escalade
    Join Date
    Mar 2011
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    speedwell tn,
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    7,233
    Quote Originally Posted by kentd
    Sheesh! New HVAC control module failed to fix the problem.

    Tonight I broke out my Archer analog multimeter and went to work.

    In the end, here is what I found: The blower control module is not getting 12V from the battery as it should. Instead, I measured a measly 3V between the power and gnd (ORN and BLK) wires feeding the blower control module. This was with the blower control module harness not plugged in, so I know the blower control module is not at fault.

    Stepping back, I went to the underhood fuse box and pulled the RR HVAC fuse. I found 12V on the hot side of the RR HVAC fuse. Plugging the RR HVAC fuse back in halfway, I was able to probe both sides of the fuse and found 12V on each side.

    Next, I went to the back of the vehicle and found the power harness that feeds the blower control module. I unplugged it and measured the pins and found that it measured 3V at the power harness connector.

    So it looks like I have a problem with the power distribution to the rear blower control module.

    Has anyone run into this problem before?

    Here is the wiring diagram. Does anyone know how the RR HVAC power feed snakes through the vehicle? Somewhere in there is a 9V drop.
    I am surprised you ain't blowing that fuse like crazy as it sounds like a short somewhere between the fuse and the blower

  6. #5
    kentd is offline Cadillac Owners Member
    Automobile(s): 2004 Escalade ESV
    Join Date
    Sep 2011
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    9

    Re: rear air system blower fan won't turn on

    Found the problem!

    Inline connector C206 is behind the left front kick panel and pin A6 is the RR HVAC power feed to the aux blower control module.

    I jiggled the connected and that immediately brought the voltage at the aux blower control module from 3V up to 12V.

    Next I pulled the RR HVAC fuse and disconnected the connector to have a look.

    Looks like heat damage on this pin connection.

    Now I'm trying to figure out my next move. My thought is to just remove this connector from the power path and connect the 2 wires together directly.

    Not sure what caused the heat damage:

    1. Did the blower control module/blower motor go bad and pull excessive current through the connector? If so, I might need to replace the blower motor too.

    or

    2. Did the resistance inside the connector increase over time, which caused excess heat dissipation in the connector itself?

    A bit of a chicken or the egg question on whether the blower or the connector was the source of the initial problem.

    Thoughts?
    Attached Images

  7. #6
    mitch2264's Avatar
    mitch2264 is offline Cadillac Owners Member
    Automobile(s): Cadillac Escalade Platinum
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    Dec 2007
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    ATL
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    77

    Re: rear air system blower fan won't turn on

    Good job finding that!! Interesting how that happened--a mystery indeed.

  8. #7
    the cadillac man's Avatar
    the cadillac man is offline Cadillac Owners Master
    Automobile(s): 03 cadillac escalade
    Join Date
    Mar 2011
    Location
    speedwell tn,
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    Quote Originally Posted by kentd
    Found the problem!

    Inline connector C206 is behind the left front kick panel and pin A6 is the RR HVAC power feed to the aux blower control module.

    I jiggled the connected and that immediately brought the voltage at the aux blower control module from 3V up to 12V.

    Next I pulled the RR HVAC fuse and disconnected the connector to have a look.

    Looks like heat damage on this pin connection.

    Now I'm trying to figure out my next move. My thought is to just remove this connector from the power path and connect the 2 wires together directly.

    Not sure what caused the heat damage:

    1. Did the blower control module/blower motor go bad and pull excessive current through the connector? If so, I might need to replace the blower motor too.

    or

    2. Did the resistance inside the connector increase over time, which caused excess heat dissipation in the connector itself?

    A bit of a chicken or the egg question on whether the blower or the connector was the source of the initial problem.

    Thoughts?
    That damage is because of a loose connection

  9. #8
    jlit is offline Cadillac Owners Member
    Automobile(s): 2006 Escalade ESV
    Join Date
    Sep 2013
    Posts
    1

    Re: rear air system blower fan won't turn on

    Found the exact same problem on my 2006 ESV. Changed all the same things, then found your thread. Giggled orange wire and now blower works. Went for a rear with rear AC. Thank you, next stop was dealer, $$$$$.

    Quote Originally Posted by kentd View Post
    Found the problem!

    Inline connector C206 is behind the left front kick panel and pin A6 is the RR HVAC power feed to the aux blower control module.

    I jiggled the connected and that immediately brought the voltage at the aux blower control module from 3V up to 12V.

    Next I pulled the RR HVAC fuse and disconnected the connector to have a look.

    Looks like heat damage on this pin connection.

    Now I'm trying to figure out my next move. My thought is to just remove this connector from the power path and connect the 2 wires together directly.

    Not sure what caused the heat damage:

    1. Did the blower control module/blower motor go bad and pull excessive current through the connector? If so, I might need to replace the blower motor too.

    or

    2. Did the resistance inside the connector increase over time, which caused excess heat dissipation in the connector itself?

    A bit of a chicken or the egg question on whether the blower or the connector was the source of the initial problem.

    Thoughts?

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