Heated Seats, HVAC Module Tech/Repair Help - Ford Mustang Forum
 
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post #1 of 7 (permalink) Old 03-16-2011 Thread Starter
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Heated Seats, HVAC Module Tech/Repair Help

To make a long story short, my car was at the dealer to get the driver side lower seat cover replaced under warranty due to factory defects.

I dropped the car off with working heated seats; after driving home I noticed the seats now no longer work.

Some Notes:

- The dealer disconnected the battery (see below related HVAC module question)
- All Primary plugs (at least the ones I can see under the seat with out removing it) appear to be plugged in.
- Both the Relay Trigger Fuse & Main Heated Seat supply fuses are good & pass voltage when they should.
- Both of the heated seat buttons light up and stay on when pressed
- Each seat has its own ground (doubt its a bad or loose ground)
- The relay control box is under the driver side seat, I have not removed the seat to test it yet. According to the wiring diagram each seat has its own relay within the box, I also find it hard to believe that both could be bad at once unless this box has some kind of common circuit for both seats (doesn't appear to).

The question:

Reviewing the wiring diagram; apparently the HVAC Control Module logic is what triggers the coils in the heated seat relay control module to gate power to the heating pads in the seats. Does anyone on here know if the HVAC control module needs to complete some sort of re-learning cycle or drive cycle when the battery is disconnected? Is this module even that smart?

As I see it now the only possibilities for both seats not working are:

1. HVAC Control Module needs to be re-learned or configured after battery has been disconnected?
2. Something is not plugged in; although I don't see anything unplugged under the driver seat (with out removing it and looking further) that would affect both seats. The main junction plugs appear to be connected.
3. Bad Relay Control Module


Wiring Diagram: Ford Service Manuals - Wiring Diagrams


Any input in regards to how the HVAC Control module logic operates the heaters (or anything ive missed in general) is appreciated.


2011 Mustang GT Premium 400A: Black/Black, Brembo Pack, Comfort Pack, 3.55s, 6 Speed MT, GT500/CS Rear diffuser & roost guards.
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post #2 of 7 (permalink) Old 03-16-2011
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Originally Posted by BadSector View Post
To make a long story short, my car was at the dealer to get the driver side lower seat cover replaced under warranty due to factory defects.

I dropped the car off with working heated seats; after driving home I noticed the seats now no longer work.

Some Notes:

- The dealer disconnected the battery (see below related HVAC module question)
- All Primary plugs (at least the ones I can see under the seat with out removing it) appear to be plugged in.
- Both the Relay Trigger Fuse & Main Heated Seat supply fuses are good & pass voltage when they should.
- Both of the heated seat buttons light up and stay on when pressed
- Each seat has its own ground (doubt its a bad or loose ground)
- The relay control box is under the driver side seat, I have not removed the seat to test it yet. According to the wiring diagram each seat has its own relay within the box, I also find it hard to believe that both could be bad at once unless this box has some kind of common circuit for both seats (doesn't appear to).

The question:
Reviewing the wiring diagram; apparently the HVAC Control Module logic is what triggers the coils in the heated seat relay control module to gate power to the heating pads in the seats. Does anyone on here know if the HVAC control module needs to complete some sort of re-learning cycle or drive cycle when the battery is disconnected? Is this module even that smart?

As I see it now the only possibilities for both seats not working are:

1. HVAC Control Module needs to be re-learned or configured after battery has been disconnected?
2. Something is not plugged in; although I don't see anything unplugged under the driver seat (with out removing it and looking further) that would affect both seats. The main junction plugs appear to be connected.
3. Bad Relay Control Module


Wiring Diagram: Ford Service Manuals - Wiring Diagrams


Any input in regards to how the HVAC Control module logic operates the heaters (or anything ive missed in general) is appreciated.
Instead of going through all this work, why don"t you just take it BACK to the dealer and have him fix it right,that"s why they have (warranties) then you will be happy again.

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post #3 of 7 (permalink) Old 03-16-2011 Thread Starter
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Originally Posted by 5.0 Coyote View Post
Instead of going through all this work, why don"t you just take it BACK to the dealer and have him fix it right,that"s why they have (warranties) then you will be happy again.
Because I am more electronically competent then most of the techs in a dealership; almost guaranteed.

I don't want them mindlessly ripping through my car scratching interior panels and paint work perusing mundane simpleton diagnosis processes.

My knowledge stops at the actual logic behind the HVAC integration with the system, which is why I am asking for specifics regarding how this system operates the heated seat relays (and if the HVAC module is afflicted by a battery disconnect).

No one works on your car as carefully as you do; frankly because no one gives a **** about your stuff.

If I can isolate the problem I rather repair it myself or at least shorten their diagnosis process there by reducing their contact time & area with the car.

While most dealerships have the right intention to do good work, the dealerships simply don't get paid enough for warranty work or have enough time in a day to give a crap.

The thought didn't occur to me to simply drop it off.

I find it less stressful to diagnose and/or repair the problem myself rather then have my car damaged and then stress and argue over that.

2011 Mustang GT Premium 400A: Black/Black, Brembo Pack, Comfort Pack, 3.55s, 6 Speed MT, GT500/CS Rear diffuser & roost guards.
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post #4 of 7 (permalink) Old 03-16-2011
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Originally Posted by BadSector View Post
No one works on your car as carefully as you do; frankly because no one gives a **** about your stuff.
I'm of the opinion that they do need to give a damn, and as the vehicle owner it's my job to identify to the dealer any of his employees who may not.

I have had ... oh, 70% or so success rate employing this philosophy with dealers and 100% success rate leaving dealers who refuse to agree with me about it.
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post #5 of 7 (permalink) Old 03-16-2011 Thread Starter
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Originally Posted by Taskiss View Post
I'm of the opinion that they do need to give a damn, and as the vehicle owner it's my job to identify to the dealer any of his employees who may not.

I have had ... oh, 70% or so success rate employing this philosophy with dealers and 100% success rate leaving dealers who refuse to agree with me about it.
Then you get the dealership service managers that do agree with this philosophy yet the techs who don't give a crap still damage components.

And often they will do the right thing (give you a rental, replace the parts they damaged, all at no cost to you - yada yada....) but its still a hassle.

2011 Mustang GT Premium 400A: Black/Black, Brembo Pack, Comfort Pack, 3.55s, 6 Speed MT, GT500/CS Rear diffuser & roost guards.
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post #6 of 7 (permalink) Old 02-07-2012
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Heated Seats, HVAC Module Tech/Repair

Electrical problems on HVAC systems that despite the depth of technical detail you will find here about all components of air conditioners and heat pumps, most service calls for non-working air conditioners or heat pumps turn up an electrical problem. So if your A/C system is just not working at all be sure to check all of our electrical and control setting suggestions first.
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post #7 of 7 (permalink) Old 02-08-2012
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Quote:
Originally Posted by BadSector View Post
To make a long story short, my car was at the dealer to get the driver side lower seat cover replaced under warranty due to factory defects.

I dropped the car off with working heated seats; after driving home I noticed the seats now no longer work.

Some Notes:

- The dealer disconnected the battery (see below related HVAC module question)
- All Primary plugs (at least the ones I can see under the seat with out removing it) appear to be plugged in.
- Both the Relay Trigger Fuse & Main Heated Seat supply fuses are good & pass voltage when they should.
- Both of the heated seat buttons light up and stay on when pressed
- Each seat has its own ground (doubt its a bad or loose ground)
- The relay control box is under the driver side seat, I have not removed the seat to test it yet. According to the wiring diagram each seat has its own relay within the box, I also find it hard to believe that both could be bad at once unless this box has some kind of common circuit for both seats (doesn't appear to).

The question:

Reviewing the wiring diagram; apparently the HVAC Control Module logic is what triggers the coils in the heated seat relay control module to gate power to the heating pads in the seats. Does anyone on here know if the HVAC control module needs to complete some sort of re-learning cycle or drive cycle when the battery is disconnected? Is this module even that smart?

As I see it now the only possibilities for both seats not working are:

1. HVAC Control Module needs to be re-learned or configured after battery has been disconnected?
2. Something is not plugged in; although I don't see anything unplugged under the driver seat (with out removing it and looking further) that would affect both seats. The main junction plugs appear to be connected.
3. Bad Relay Control Module


Wiring Diagram: Ford Service Manuals - Wiring Diagrams


Any input in regards to how the HVAC Control module logic operates the heaters (or anything ive missed in general) is appreciated.
There is probably something wrong with the heater mat in the seat cushion that was worked on. The back rest and cusions mats are in series so a fault there would take out the entire heated seat. Does the other seat work? Check the fuse. They may have removed it while they were working on it,or shorted something out and blew it. If you look in the service manual,there is a detailed procedure for troubleshooting the heated seats. The only thing that I can think of that would plausibly take out both seats would be a harness disconnected or a fuse blown or removed.

Sometimes, I see cops with their backs turned writing tickets. When I drive by I can see them stick their heads up,and sniff the air,catching a whiff of exhaust and burning rubber,the crimson smell of speed,telling them a Race Red Mustang is somewhere nearby!


2012 Race Red GT, Kenwood Navigation system with Metra dash kit,GT500 steering wheel,Steering wheel buttons INCLUDING BT enabled,Takeoff leather seats with seat heaters.
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