T4 Heater temperature control

[Cometboy]

Can anyone comment on the Heater Control on a T4 – 2002 petrol 2.5 LWB?
This has been a long-term issue for years and I just put up with it!
The problem is the temperature adjustment control (effective bit) is basically limited to the first bit of the control knob. Like a few mm! Hence it is very tricky to set the temperature.
This model had the AC unit fitted in Australia by VW and is one of the models with the strange A/C Thermo fan wiring that I have previously posted about trying to correct. But I don’t think the two are related.
Would the most likely cause be the water temperature control valve? Cable movement seems fine on it. Are there known issues with the temperature control valve and age. Vehicle is very well maintained and mint condition…. So just trying to sort out these long-term things I’ve never gotten around to.
Any views appreciated.

[jets]

I had a problem with my first T4 where the control wouldn't switch right off. I was new to the van at the time & drove to Melbourne in the hottest time of the year with my Son & future daughter in law. If I knew what to do it could have easily adjusted on the side of the road in the night. I soon learned later the temp. is controlled by a simple flow valve at the end of the cable going to the switch on the dash.
The cable needs to be lightly lubricated & perfectly straight [no kinks] otherwise the control knob can be easily damaged.
I have read probably 20 years ago now that the Polo of the same vintage used the same switch. From memory I replaced the valve in the same van with a new one that was very cheap.
Check the adjustment of the cable clamp on the valve that the movement goes from fully closed to fully open.

[Seano]

Almost certainly, the diecast lever behind the rotary dial will be broken. It converts the rotary action into a push and pull motion. Unfortunately, VW saw fit to route the cable in a deep U shaped path through the firewall to the tap under the expansion bottle in the engine bay.

I tried to fix it back in the day to no effect and resorted to a generic choke control switch mounted on the empty panel below the heater controls. It's worked perfectly across the nearly two decades since.