heater permantly on

mirage · Post by **mirage** » 12 Jun 2022, 20:55

I recently send my S60r to the aoto-elecrician ( car Kept cutting out due to faulty crank sensor ) on returning the heater is on hot, no matter where the knobs are.Anyone know how to fix this.

chris11211 · Post by **chris11211** » 12 Jun 2022, 23:43

The sensors on the engine? If so then idk what he did. Volvo's are constantly pumping liquid to the heater core so something must've happened to the levers. Could you remove the two side panels that flank the gear shifter and the panels below the glove box and steering wheel. Manipulate the temperature knobs while the powers is on, and see if the arms start to move

Post by **RickHaleParker** » 13 Jun 2022, 06:05

Sounds like the power interrupts are producing a software corruption in the ECM.

Does it return to normal after you turn the car off?
If so, fix the faulty sensor so it quits producing a power interrupt.

If the ECM permanently stuck.

1 Put key on POS 0 (off)
2. Disconnect the negative battery terminal.
3. Put the key in POS II (run).
4. Reconnect the negative battery terminal.

This will force the control modules to reinitialize and might get it out of the stuck condition.

mirage · Post by **mirage** » 13 Jun 2022, 21:18

Thanks will try, also since the auto- electrician visit the engine does not boost, could is be for the same reason,

Post by **cn90** » 13 Jun 2022, 23:22

Search forum for the heater core DIY so you can remove the side trim to look at the heater core itself.

Now turn the key to position II, set the temp to cold vs heat and see if the linkage arm moves at all.
The linkage arm may be broken (did someone replace the heater core recently) or the small electrical motor that drives the linakge arm is bad.

I posted photos of the HVAC linkage arm in this forum.