F430 Heater

Is your coolant level okay?

 

So the blower fan is still working?

Unfortunately, there are just too many components in the heating system. Could be:

1) intermittent hot water recirculation pump (check fuse for signs of melting... PSF13 behind driver). From memory, the pump itself in the frunk area is hard to get to.
2) intermittent hot water valve ("TGK"). It has a position feedback potentiometer which could be playing up.
3) faulty sensors (there are lots of them). Sensors for treated (duct) air, cabin air, driver's mirror outside air temperature, sun radiation. Check mirror for damage. Audibly check that the little suction fan on the inside cabin air sensor is running (there is a small air grille in the dash to the right of the steering column). Sometimes dust builds up on these type sensors. On aircraft cabin sensors, I used to use one ply of toilet paper held up against the grille to see if the suction fan was still operating (it may work on the F430).
4) faulty ECU
5) faulty control panel
6) wiring issue

It may be best to go to your dealer and have him her see if there are any faults in the HVAC ECU memory. Otherwise you could be looking in all the wrong places.

 

Assuming the fan motor is working, look up. Technozen- Electronics.co.uk. The ac unit is fitted with a Rover 45-MG ZS climate controller. This part is not available but these people will repair your for about £50. Good info on the site as to the failure issues