Carver fanmaster 4000 fan speed going crazy...help appreciated

[Aibo82]

Hi

I have a Carver fanmaster 4000 in my van and has been working fine up until these past few weeks if I leave it on electric 2kw/1kw with the fan its fine until the elements are hot and the fan is controlled, but then all of a sudden after a while the fan speed goes crazy and I can't control it other than turning it off or selecting gas or just the fan mode,

the heater itself is very hot the fan just speeds away regardless of the slider setting and if I move from 2kw to 1kw when this happens the fan gets faster.

Any ideas what this could be? I can select cold fan on the slider and move the speed fine so I don't think its the slider pcb?

Thanks

 

[ProfJohnL]

Hello Aibo

Welcome to the forum.

Uncontrolled speed will almost certainly be a problem with the control circuit, This will need the repaired or replaced, and I suggest you contact arcsystems.biz who are experienced with these Carver systems.

I have to point out the obvious fact your heater is now at least 20 years old, and they do from time to time need servicing. One of the continual problems with fans (all makes) , is they become clogged with dust and debris, and this should be cleaned out carefully to avoid bending or unbalancing the fan rotor.