Dual zone climate control issue

[theholmesmob]

G'day All

I have just today taken my Tig in for an issue with the dual zone climate control. As I understand it you have the auto light lit and set your temp by the knobs and away you go. The issue has been that it may be, say 8 deg outside and the temp knob set at 23 deg inside the car but the system, more so when it is sunny, will start blasting cold air.

Of course the Tig was connected to the computer and no faults found, which is ok if the sensors know they are faulty because they will tell the computer. On the other hand if they think they are ok they tell the computer that.

Anyway got the Technician to come out and explain the climate control to me. I'm now more baffled than before and the Tig owners manual is light on the detail for the 'climatronic' side of things.

Essentially he was saying that in winter months have the AC button off. Anyways after some faffing with the unit we established that even with the AC off the unit was not blowing 25 degree air.

Just wondering if anybody has had a similar issue and definitive dual zone climate control user guidance instructions.

Thanks for reading.

David

[Transporter]

Of course the Tig was connected to the computer and no faults found, which is ok if the sensors know they are faulty because they will tell the computer. On the other hand if they think they are ok they tell the computer that.

Anyway got the Technician to come out and explain the climate control to me. I'm now more baffled than before and the Tig owners manual is light on the detail for the 'climatronic' side of things.

Sensors don't say to computer that they're OK or Faulty. The computer monitors the sensors and compares the data it receives and if they're out of range fault code is stored, very often with other data. This is how it works, without going onto too many details.

I think that our works very similar when I set the temperature the fan goes to higher speed than I originally set. That could be explained that the system wants to quickly reach the preset temperature. When just start driving there is nothing warmer to quickly reach the 25deg.C , so it will start blowing the air from the heater box that is not hot enough till the engine warms up a bit.

I will recheck tomorrow, just to be sure.

[theholmesmob]

Thanks for the response Transporter. As you quite rightly pointed out I'm completely ignorant in all things mechanical and electrical for that matter, especially when they pertain to a car!!

I always thought that to keep a nice year round temp say of 23/24 deg the AC light would be on and the climate control would either pump out hot or cold air as appropriate.

The explanation I got was that if you wanted heat then AC should be off otherwise the unit will still pump cold air because the AC is on. That seems a stretch.

I mean after a session at bootcamp this morning I proceeded the short drive home with the AC light off and the temp set at 24deg. Before I knew it the car was fogging up, rectified by turning AC on. I've also experimented with the AC light on and turned the knob for full heat and what do you know, nice hot air is coming out.

Climate control is just that - set and forget. I'll keep you posted.

Cheers

David

[dogbowl]

One thing to remember with 'set and forget' systems, is that to maintain a temp they will often blow cool air at face level, while blowing warm air below, concurrently.

You only notice the cool air, and think something is wrong, but put your hand in to the footwell and you should feel warm!

[Jamanta]

The explanation I got was that if you wanted heat then AC should be off otherwise the unit will still pump cold air because the AC is on. That seems a stretch.

Completly wrong! When the AC is on the HVAC (heating, ventilation and air conditioning) unit should mix the cold and hot air to get the right temperature. While in AUTO, cold air is blown through the front nozzles and warm air to the feet, but not at the same time as mentioned here before.
The system is not perfect and sometimes it will blow a bit of cold air when it's sunny but cold outside. But it shouldn't be too cold.
If pure cold air is coming from the nozzles in your case I would ask them to replace the "Sunload Sensor". As the name says, this sensor reads the amount of sunload and gives the input to the HVAC unit.

I hope it helps you in some way.

Cheers

I hope

[MGV]

Jeez, its seems like i now have to book in to a 2 day seminar on how to use the air-con...

[DionM]

Complete rubbish about running with AC off. As you experienced, one of the other benefits of AC is dehumidification which is great in winter. I always run my AC during winter.

[ethosguy]

Complete rubbish about running with AC off. As you experienced, one of the other benefits of AC is dehumidification which is great in winter. I always run my AC during winter.

Quite so...

Has anyone discussed that the heater traditionally is a supplimentary radiator tapped off the cylinder head coolant prior to the recirculate/radiator thermostat valve; it can't provide heat until the engine has heat to offer? This could be changing with aux electric heaters???

Heating delay can compounded by diesel engines because they require a more solid construction to cope with higher cylinder compression ratios and take longer to warm up because of the additional thermal mass.

Our Tig TDI is notably slower in delivering heating than our petrol Subaru. Interestingly the Subi won't circulate cold air when set to climate control, it waits until the engine has warmed up unless you select defrost, which automatically activates the A/C. This might be a comfort or engine preservation over ride?

[clip]

Interestingly the Subi won't circulate cold air when set to climate control, it waits until the engine has warmed up unless you select defrost, which automatically activates the A/C.

My Tig does this though, I thought they all did

[theholmesmob]

Thought I better update on what has happened .

I got the car back on Friday.... and I think they have solved the problem.

I believe that they have replaced the solar sensor situated in the middle front of the dash. This morning was a good test as it was sunny, about 10 deg outside and I had the unit set at 23 deg with the little fan AUTO lit and the A/C lit as well. The temp regulated well and after some driving into the sun the temp did cool a touch but NOWHERE near the behaviour before where it would increase fan speed and the temperature plummeted.

I believe these technicians contacted VW to ascertain whether they have dealt with this issue before. As a result that is when the called me up to get the car back for this work. I must add that depending on what office bod you talked too, it was the A/C unit being replaced or sensors or both - but I am confident that the young fella who mostly dealt with this issue was correct when he said that yes they were replacing the solar sensor as he had ordered the part himself.

Gotta say that every time I hear "we plugged it into the computer and the computer says NO" drives me crazy. Recent issue with our other car has left us replacing some very expensive parts that did not fix the problem and we will now have to wait until the computer throws another fault code (won't be until next winter) or something fails. Can't wait.

Hope this helps others and will update again if needed.

Cheers