Multiple ECC Fault codes, Heater hot all of the time, no ECC flashing lights

AlanHMultiV70s · Post by **AlanHMultiV70s** » 24 Aug 2025, 03:27

Hello I'm new to the Forum, I'm hoping that someone may have some solution to this issue.

I've scanned the ECC on my 1997 V70CD 2.5NA using Vol FCR as I have found that the heater is hot all of the time. The A/C compressor is cutting in and out, the fan control works and varies the speed of the fan and there are no flashing lights on the ECC. I also substituted a replacement, used ECC module for the existing one and this made no difference

I'd be very greatful if anyone has any idea of what could be causing this. Thanks

Post by **abscate** » 24 Aug 2025, 03:47

Looks like the dampers are either stuck or both motors have gone. That would be a rarity so I would have a good look at the connectors on the front of the ECC control unit.

Volvos regulate temperature by mixing hot air with cool/ac chilled sir so you have located the problem, now to sort out if it’s

Control unit
Wiring/connectors
Motors
Dampers

I miss the Hatters in the EPL. Hope they find their way back

Post by **scot850** » 24 Aug 2025, 03:58

Have you checked and cleaned the cabin temperature sensor behind the dash and to the left of the ECC? If this is choked they system will not work. There is also a temp sensor in the ducting to the between the fan and the resistor unit or possibly to the left of the resistor unit.

Neil.

AlanHMultiV70s · Post by **AlanHMultiV70s** » 24 Aug 2025, 04:38

Great, thanks for the quick replies!

The cabin temp sensor was replaced about 6 months ago, if it was faulty again, I might think that the lights on the ECC would be flashing like last time? I'll check the sensor which is associated with the fan as that seems a possibility given the codes.

Maybe the temp control flaps are inactive due to the other sensor fault?

Yes, Luton in the EPL was very exciting while it lasted