Confirmed: you cannot change the hot water control valve from just under the hood.

[awags]

I accidentally deleted my post?
Graham, are you sure the cable is adjusted properly and not holding the switch on or off a little bit? I was recently messing around on one of mine and Im pretty sure the cable will still override that bi-metallic spring and turn on or off the vacuum. The spring I think just acts like an automatic temp control, fine tuning and holding the temp comfortable.

[Graham Rollo]

Thanks will check as did test but with cable off