Rear aircon blowing hot/ambient but not cold

stew · Jul 27, 2017

Hi,

I've got a 2011 T5.2 Beach with Climatronic.

The rear aircon unit will not blow cold, just ambient and hot. It doesn't matter whether the temperature is set from the head unit or the rear control unit. Set at the lowest temp (18C) which should be cold, it blows ambient. Hot air comes out when the temp is pushed up. The front system works fine across cold, ambient and hot.

So I took the cover off the rear unit (bottom right-hand side when standing at the rear) and see that the white control/actuator rod moves up and down when I adjust the temperature control. There is nothing loose, all plugs are inserted, no obvious broken wires. I took the actuator rod off and adjusted the temperature valve manually, but no cold.

Ref here for a video and a tip from someone who wasn't getting hot air

Is there anything else obvious to look at/check before visiting VW?

Thanks!

WelshGas · Jul 27, 2017

stew said:
Hi,

I've got a 2011 T5.2 Beach with Climatronic.

The rear aircon unit will not blow cold, just ambient and hot. It doesn't matter whether the temperature is set from the head unit or the rear control unit. Set at the lowest temp (18C) which should be cold, it blows ambient. Hot air comes out when the temp is pushed up. The front system works fine across cold, ambient and hot.

So I took the cover off the rear unit (bottom right-hand side when standing at the rear) and see that the white control/actuator rod moves up and down when I adjust the temperature control. There is nothing loose, all plugs are inserted, no obvious broken wires. I took the actuator rod off and adjusted the temperature valve manually, but no cold.

Ref here for a video and a tip from someone who wasn't getting hot air

Is there anything else obvious to look at/check before visiting VW?

Thanks!

You need a Diagnostic of the Car Electronics, either via VW or an OBD dongle like Carista .

hirsty · Jul 27, 2017

I don't know anything about secondary aircon, but do they need "re-gassing" separately or does it all work off one?

WelshGas · Jul 27, 2017

hirsty said:
I don't know anything about secondary aircon, but do they need "re-gassing" separately or does it all work off one?

Both work off the same system. That is why if you go to a 3rd Party AirCon company you should ensure that they know if you have Climatronic or Manual AirCon as different amounts of Refrigerant are required.

Petri Wachter · Aug 7, 2018

Hi, I'm new in this forum, writing from Finland.
I had similar problem with rear AC. When I adjusted temp to "low" then there was cold coming from air vents, but if I set to 18deg then after engine was warm there was only hot/warm air from air vents. I had car diagnosted and there was temp sensor broken.Error code was G174. Sensor it self cost only 40€ but location was a different story. Sensor is behind rear ac unit so you have to remove the right rear panel first. Then the AC unit must be empty. Whole car AC system totally empty and them the rear ac can be removed. Sensor cannot be changed unless you dismantle whole ac unit. So before all this I recommend to get some diagnostic made just to be sure that it is this sensor what I mean. Also I had some fuses blown.
Picture is a bit unclear, sorry...
I hope this information is helping you out.

stew · Aug 7, 2018

Here's the fix to the problem identified by the VW Garage...

There was a leak in the system. They filled it with UV sensitive gas to identify where. Anyway, they replaced the rear evaporator and expansion valve. The automatic air quality sensor under the bonnet was also broken as indicated by a failure code although this wouldn't have caused the air-con to fail. Only cost 1,800 CHF / 1,400 quid! mainly due to time consuming removal and rebuilding of the rear and where the sensor is located.

Petri Wachter · Aug 7, 2018

Problem was not fixed in my case... Just today after driving few minutes my kids noticed that there is hot air coming from rear air vents again...Called to local VW service who originally "fixed" my car. VW electrician is trying to find the problem...and who know what it will cost this time. I also have problem in the front of the car, air vent motors are keeping some noise and there is some 3 motors and plastic gears brake and start to keep noise. These are in quite difficult place.
Last owner of this car didnt keep so good care of the car.

Zhorod · Aug 28, 2021

stew said:
Hi,

I've got a 2011 T5.2 Beach with Climatronic.

The rear aircon unit will not blow cold, just ambient and hot. It doesn't matter whether the temperature is set from the head unit or the rear control unit. Set at the lowest temp (18C) which should be cold, it blows ambient. Hot air comes out when the temp is pushed up. The front system works fine across cold, ambient and hot.

So I took the cover off the rear unit (bottom right-hand side when standing at the rear) and see that the white control/actuator rod moves up and down when I adjust the temperature control. There is nothing loose, all plugs are inserted, no obvious broken wires. I took the actuator rod off and adjusted the temperature valve manually, but no cold.

Ref here for a video and a tip from someone who wasn't getting hot air

Is there anything else obvious to look at/check before visiting VW?

Thanks!

Hi,

Did you get anywhere with this. I though I had a problem with mine but it turns our rear does not have Aircon despite the unit in the back having a label that says HVAC, it will only get air from outside or heat air.

Paul