Cockpit Heater. Driver okay...Passenger Getting Cooked
01-21-2015, 07:32 PM
#1
Rennlist Member
Thread Starter
Cockpit Heater. Driver okay...Passenger Getting Cooked
Searched the forum and found nothing. Just one member with 3 posts back in October. No responses. Cayenne is under warranty and the dealer performed the the ATI Group 8 #1102 8758 bulletin: cover the Driver's vent vent holes which will blow air onto the back of the infrared driver/cabin sensor. It didn't work.
I am looking for ideas for when I take it back to the dealer. This is a 2 zone system. They said they've never seen anything like this. I don't need techs tearing down the front of the cockpit unintentionally inducing more issues trying to figure this beast out. Top things come to mind are:
- Sticking servo motors or flaps
- one of several internal temp sensors has failed
- HVAC computer has failed
- CANi and MMI comms are breaking down
- Not so clean power mucking things up
- your ideas....
Bottom line up front, Auto has a mind of its own and will cook the passenger, and leave the driver okay. Switching the passenger over to Manual can control heat delivery, but not Auto. Quick summary of what I am seeing:
- Starting settings and measurements. Outside air temp 32F. HVAC: Auto, Mono/Sync, 65F set, coolant and oil temp stabilized and 30 minutes into the drive, leather surrounding the driver’s infrared sensor measured 81F (using a non-contact instrument) , Driver’s center vent about 65F (probe), Passenger’s center vent about 65F (probe)
- Slowly raised the setting one degree at a time over a 15 minute period to 69F
- No temperature change noted in the center vents. The leather surrounding the driver’s infrared sensor was always between 79-81F
- Raised the temperature setting to 74F from 69 all at once
- Over a 2 minute period, the Driver’s vent temp went to 72F, Passenger’s vent started to run away hitting 120F and still climbing
- Lowered the temperature setting to 68. Waited 2 minutes. No change except the Passenger vent temperature was still climbing towards 130F
- Switched Passenger side to manual, selected floor and torso level vents and watched the temperature go back down and thereafter, the output temperature of the air could be manipulated with the passenger’s temp switch and the temp resumed comfortable temperatures.
I am looking for ideas for when I take it back to the dealer. This is a 2 zone system. They said they've never seen anything like this. I don't need techs tearing down the front of the cockpit unintentionally inducing more issues trying to figure this beast out. Top things come to mind are:
- Sticking servo motors or flaps
- one of several internal temp sensors has failed
- HVAC computer has failed
- CANi and MMI comms are breaking down
- Not so clean power mucking things up
- your ideas....
Bottom line up front, Auto has a mind of its own and will cook the passenger, and leave the driver okay. Switching the passenger over to Manual can control heat delivery, but not Auto. Quick summary of what I am seeing:
- Starting settings and measurements. Outside air temp 32F. HVAC: Auto, Mono/Sync, 65F set, coolant and oil temp stabilized and 30 minutes into the drive, leather surrounding the driver’s infrared sensor measured 81F (using a non-contact instrument) , Driver’s center vent about 65F (probe), Passenger’s center vent about 65F (probe)
- Slowly raised the setting one degree at a time over a 15 minute period to 69F
- No temperature change noted in the center vents. The leather surrounding the driver’s infrared sensor was always between 79-81F
- Raised the temperature setting to 74F from 69 all at once
- Over a 2 minute period, the Driver’s vent temp went to 72F, Passenger’s vent started to run away hitting 120F and still climbing
- Lowered the temperature setting to 68. Waited 2 minutes. No change except the Passenger vent temperature was still climbing towards 130F
- Switched Passenger side to manual, selected floor and torso level vents and watched the temperature go back down and thereafter, the output temperature of the air could be manipulated with the passenger’s temp switch and the temp resumed comfortable temperatures.
Last edited by CAVU; 01-21-2015 at 08:34 PM.
11-21-2015, 11:55 AM
#2
Rennlist Member
Thread Starter
Closed out as solved.
I bought this in Oct '14 as a CPO and the selling dealer completed the 40k service as part of the deal. When the passenger footwell tubing was removed to access and replace the cabin air filter, the foot well temp sensor was removed from its mounting, and when the temp sensor was reinstalled, it was not placed back where it belongs. The servicing dealer also shared with me that there is more than one wrong place that the sensor can end up (frankly I don't know if this is BS or not because when I look at the AllData servicing for that temp sensor, there is only one way for it to be remounted). Soooooo, the computer has not had any info from the footwell, except..."it's always cold" so, pour on the heat!!! This is their third try and they are swearing that it is now working perfectly. I've not tried to service the cabin air filter, but I had wondered at one point if this might not be the problem. They are chasing one more unrelated gremlin in the car so I might not get the car back for a day or two. But when I do, and if this solved the problem, I'll come back and close this out as a solution.
as of the date of this posting, I can confirm that the misplacement of the sensor was the issue. The selling dealer screwed the pooch and my servicing dealer finally fixed it.
I bought this in Oct '14 as a CPO and the selling dealer completed the 40k service as part of the deal. When the passenger footwell tubing was removed to access and replace the cabin air filter, the foot well temp sensor was removed from its mounting, and when the temp sensor was reinstalled, it was not placed back where it belongs. The servicing dealer also shared with me that there is more than one wrong place that the sensor can end up (frankly I don't know if this is BS or not because when I look at the AllData servicing for that temp sensor, there is only one way for it to be remounted). Soooooo, the computer has not had any info from the footwell, except..."it's always cold" so, pour on the heat!!! This is their third try and they are swearing that it is now working perfectly. I've not tried to service the cabin air filter, but I had wondered at one point if this might not be the problem. They are chasing one more unrelated gremlin in the car so I might not get the car back for a day or two. But when I do, and if this solved the problem, I'll come back and close this out as a solution.
as of the date of this posting, I can confirm that the misplacement of the sensor was the issue. The selling dealer screwed the pooch and my servicing dealer finally fixed it.
