405 1.9TD - heater with a mind of it's own!

[r.welfare]

My 405 (Phase 2 Hunter 1.9TD estate, 1993 model, with aircon, although this no longer works due to a leak somewhere in the system) has a heating system with a mind of it's own - basically, with the temperature slider at the coldest setting, every so often the vents will decide to blow hot air for an indeterminate period. This seems to be worst when the car has been parked in high ambient temperatures.

There seems to be no simple cure for this - waggling the temp slider up and down a bit sometimes helps, as does blasting the fan speed up to 3; other times neither of these work and I have to open a window until, of it's own accord, the temperature of the air coming out of the vents corresponds with that selected!

When moving the temperature slider it does feel quite "loose", i.e. no noticeable resistance. I've not had the dash apart to look at the cables behind, which I guess is the next thing to do. Pollen filter replaced last year, and the small grille above the glovebox is clear from dust.

Any ideas gratefully received!
Richard

[evilally]

The temp control cable has a couple of clamps/clips holding it in place behind the controls. Possibly one of these has come loose or broken away? That might explain the lack of resistance in slider.