Wot he said!
Maybe we should look at a cold air feed for the heater,
Should be pretty easy to set up.
I think our cold air in the F is 'proper cold'.
Thinking about it, is your heater valve shutting off completely?
Decided to sort out my cable today, which has been stuck on hot since I got the car.
Found that the clip was loose on the cable so re lipped it and adjusted so that I was getting the correct travel. Then I found that it wasn't moving smoothly with the control knob 'skipping' part way through the cables travel. Couldn't see it snagging on anything so Im suspecting a dodgy control knob.
Also now found that on trying the cold position for the first time that with the fan on position 3 and 4 it is blowing 'coldish', but on position 1 and 2 or with it off it is still putting out hot air. Any ideas?