Heating cuts off after 5min of every increased increment. MK3 5F FR TDI

[pesix]

Hi, guessing that interior temperature sensor is giving false high results.

Starting car, until warms up during the drive, heating comes on as it should, however when set to 20C - it gets to temperature and starts blowing cold air in.
Adjusting to 21C, it comes back on again, 5 min later, it cuts off, doesn't stay on for long. 22... 23... the same behaviour.

My guess is that the temperature sensor sees a higher reading for some reason and cuts it off.

AC works fine, it's the dual zone and it does have the same behaviour on both sides.

Has anyone else had this issue?

Also, does anyone know the location of the interior temperature sensor / sensors are?

 

[cairus]

This is the Sensor

 

[nd-photo.nl]

Never would've thought that that little stub is a temp sensor

 

[pesix]

Thank you, the weird thing is, I thought there's a temp sensor on either side of the dash, just because it's dual climate, just wondering how does it see 26 on 1 side and 22 on other with 1 sensor being placed in the middle? Or it's more basic than that.

 

[SteveGSXR600K1]

The service manual show sensors for left and right vents, footwell vents, etc. Doesn't mention anywhere that there's one in the middle of the control panel.....

 

[pesix]

The service manual show sensors for left and right vents, footwell vents, etc. Doesn't mention anywhere that there's one in the middle of the control panel.....

View attachment 46835

Thanks Steve. Would obd11 be able to monitor temp readings on all corners or vcds is better suited for this? In case someone knows

 

[SteveGSXR600K1]

Thanks Steve. Would obd11 be able to monitor temp readings on all corners or vcds is better suited for this? In case someone knows

Just had a quick look in OBDeleven. If you go into Control Units, Air Conditioning, Live Data, there's Left front vent temperature, Right from vent temperature, Footwell ven temperature, Interior temperature and loads more. Plent in that section to see what yours is up to. There's also Output tests for the vent temperature flap positioning motors.

Don't know if you've tried the procedure to calibrate the flaps. I'd give that a go first.

 

[pesix]

Just had a quick look in OBDeleven. If you go into Control Units, Air Conditioning, Live Data, there's Left front vent temperature, Right from vent temperature, Footwell ven temperature, Interior temperature and loads more. Plent in that section to see what yours is up to. There's also Output tests for the vent temperature flap positioning motors.

Don't know if you've tried the procedure to calibrate the flaps. I'd give that a go first.

Steve, thank once again. I recalibrated the flaps yesterday, made no difference whatsoever, I have ordered obd11 to see the readings. Thank you for all your help. Will post the results during the week.

 

[Craig.]

The service manual show sensors for left and right vents, footwell vents, etc. Doesn't mention anywhere that there's one in the middle of the control panel.....

View attachment 46835

That is likely because it isn't a sensor that can be removed/installed, much like the photosensor in the instrument cluster that changes the dash illumination during daylight

 

[Craig.]

This is the Sensor

That centre dot is an Infrared sensor

 

[pesix]

@ViperSlider @SteveGSXR600K1 Hi, got the tool to collect the data finally last night.
Graph shows ambient temperature initially, then switched on the AC with low temp followed by AC off and temp to the max.

Couple things I noticed right away:
1. Interior temperature was at 27 constant, didn't respond to any of these changes
- Had the windows open (+8 outside)
- I jumped out from the car in case the temperature sensor in the middle of the dash is picking up my temperature. Still sitting at it's 27 28 degrees.

2.Left front temperature does it's own thing and seems to be out of the range or calibration as it's almost always +5 degrees higher up.
-It did come down to similar numbers when AC was on and it triggered to pull the high 30's down to +19, they all were within 3-4 degrees as visible at data point 99.

3. Footwell temperature sensor has a different character to other 2 sensors.

All this was done with air blowing on footwell and face.

4. IR sensor in the middle of the AC unit didn't respond to being covered with plastic sheet, by hand to pick up any temperature change.


After this test, it still had the same characteristics of cutting off after reaching each incremental step up.


No fault codes present.

Any suggestions? Tempted to find the location for each of these temp. sensors and swap them around to see if the issue is now switched to the other side. And if AC unit reading is a separate issue? Thank you.

 

[SteveGSXR600K1]

@ViperSlider @SteveGSXR600K1 Hi, got the tool to collect the data finally last night.
Graph shows ambient temperature initially, then switched on the AC with low temp followed by AC off and temp to the max.

Couple things I noticed right away:
1. Interior temperature was at 27 constant, didn't respond to any of these changes
- Had the windows open (+8 outside)
- I jumped out from the car in case the temperature sensor in the middle of the dash is picking up my temperature. Still sitting at it's 27 28 degrees.

2.Left front temperature does it's own thing and seems to be out of the range or calibration as it's almost always +5 degrees higher up.
-It did come down to similar numbers when AC was on and it triggered to pull the high 30's down to +19, they all were within 3-4 degrees as visible at data point 99.

3. Footwell temperature sensor has a different character to other 2 sensors.

All this was done with air blowing on footwell and face.

4. IR sensor in the middle of the AC unit didn't respond to being covered with plastic sheet, by hand to pick up any temperature change.


After this test, it still had the same characteristics of cutting off after reaching each incremental step up.


No fault codes present.

Any suggestions? Tempted to find the location for each of these temp. sensors and swap them around to see if the issue is now switched to the other side. And if AC unit reading is a separate issue? Thank you.

Seems like you're getting somewhere! Here's a diagram showing all the sensor locations:

 

[pesix]

Seems like you're getting somewhere! Here's a diagram showing all the sensor locations:

View attachment 46988
View attachment 46989
View attachment 46990
View attachment 46991

Thank you for pointing me into the right direction! I suspect the sensor is not via the vent on the drivers side but it's plugged from the footwell looking upwards into the vent?

 

[SteveGSXR600K1]

 

[pesix]

@SteveGSXR600K1 Thank you for the chart. Here's the latest:

1. Decided to swap the left and right vent temperature sensors around.
2. Both visually in their accurate positions
3. Swapped them around, assembled the parts back together
4. Did a scan via OBD11 - 1 Fault:

B108715 - Left vent temperature sensor Open circuit/short circuit to B+
Intermittent
Cleared the code, climate control in action for couple of minutes, scanned again - no Faults.

5. Live data recorded, same as last time:
- Interior temperature sensor must be connected to Spanish weather via WiFI? Reading HIGH while it's +10 outside / windows / doors open.
- Left hand side temperature sensor still tends to read +5 +6 degrees higher?

Coolant was coming up to 72 degrees, when applied the revs - a considerate amount of heat started to come in.

At this point I've ruled out the fact that swapping the LEFT/RIGHT sensors doesn't transfer the issue to one or another side. Or is there a reason to think it's not the case?

All of them tend to respond to the change in temperature.

Is the problem the A/C unit itself?
Re. the increased revs - should I be looking elsewhere for the problem? @ViperSlider / @SteveGSXR600K1
It's not loosing coolant or anything like that.
Thank you!