heater control noise??

[Guest]

hi guys thanks for your help before,got a 962 c4 91 got a werlin nosie comin from the heater control when i stop the engine goes on for a couple of minuites then goes????heater seems to be on even when the temp is on blue???cheers walt

 

[Dave Wilkinson]

Hi Walt,

There's a lot going on with the 964 heating system so you might have to be a bit more specific.

There is a small fan on the back of the CCU which DOES continue to run for a few minutes after you switch off the engine - it's supposed to.

When you say the heater is on even when the control is on blue do you mean that you can FEEL heat or that you can HEAR something running?? If you can feel heat in the footwells it can often be that the fibre tube which carries the heated air from the tube in the sill to the booster fans is damaged. There is one each side so you might be able to tell if one side gets more heat than the other. Cheap fix if this is the problem.

The rear blower fan (in the engine compartment) should NOT run when the temp selector is on blue. Only if the engine is really hot should the blower fan run independent of the heat selector. It may stay on after the engine is shut off to aid the cooling. It's switched by the NTC sensor in the top of the tube from the blower.

Hope that helps.

Regards

Dave