Driver seat heating and cooling not working

Hi Ray,

Thanks for the question. If they replaced the memory seat module then that eliminates one possible cause but it also limits it down because the signal follows this path. When you press the heat/cool button it sends the signal from the switch to the door/lock window switch (appears to be just a pass through), to the memory seat module. The memory seat module shares the info with the HVAC module and then sends the signal to the seat climate control module for ventilation. For heat, the MSM shares the info with the HVAC module but then it sends the signal directly to the heating elements.

Due to this small difference, the fact that neither the heat or cool work, then I would suspect your issue is either the switch for the heat/cool, the window switch (doubtful) or the wiring in between.

I attached the wiring diagrams however, the real way to test this, is to have a scan tool hooked up to it and monitor each module when you press the button on and off. Each module should see the input from the one before it which indicates it is getting the signal and it is most likely not your issue. I would suspect that the memory seat module was your issue but they just replaced that. There is a small chance that they used a module that does not have heated/cooled seats. Do you have the part number that they used? I can try to verify that it was the correct part.

Thanks.

Thanks for clarifying. Yes, that makes sense because once you get past the button (driver and passenger) and initial input of the command from the driver/passenger, the two seats are controlled independently of each other. Basically, they have their own modules that run the heater and motor for the cooler.

Without being the one doing the testing I clearly can't say with certainty but what they are telling you seems right. Plus, I would trust that if this is the dealership, that they have checked it with the scan tool on each module to see at which point the command is not reaching. Meaning they can look in each module, press the button and when the command does not register in that module then they found the problem. At that point, they just do a quick voltage check to ensure it is not wiring then condemn the module.

Feel free to keep me updated with what happens but I would be surprised if that does not correct you issue. Thanks

Just so I am clear. You got the heat/cool module that is under the driver seat? Can you send me the part number? It looks like what you took a picture of is the blower fan which is supposed to be part of the ventilation module. You actually have 4 of these. One in the seat back and seat cushion of both front seats.

Here is how this system works. You press the button to turn on the heated/cooled seats. It sends a signal to the HVAC control module. This module sends the signal to the Memory Seat Module. The MSM then sends the signal to the Climate Control Seat Module. The CCSM then determines which blower fans it needs to turn on and it sends the voltage to that blower.

I am having a hard time seeing where you tested for voltage but what you want to see is if there is voltage on the Green wire at the location that I highlighted in yellow. It it pin 2 at the 7 wire connector that is plugged into the ventilation module on the driver side floor. I traced the power voltage in red that it takes when you press the button for cooled seats for the seat and seat back.

If you have voltage here then you may be correct that the blower or heating and cooling ventilation module, is the issue. If you don't then the Climate Control Seat Module is your issue. The part number that you gave me for what they put in says that it is the heat/cool ventilation module for the passenger side. .

With all these parts being some sort of seat module the names are getting confusing.

However, it appears these ventilation modules are well known for melting so they say to replace them and the wiring harness if you find any connectors melted. It won't be the entire connector, just the plastic inside where the wires terminals are, will look distorted.

Let me know the part number of the module you plugged in and what the voltage is on this wire and we can go from there.

Ok. That helps. I am more confident that you will find voltage at that Pin 2 of that connector which will point to that ventilation module.

Keep me posted. I am interested to see how it turns out. Thanks