Bump

 

Jeez -40 C is around -40 F.
Thats cold, too dam cold for me to even go out of the house.

Are you running auto climate control?
Maybe is the SYNC setting is not enabled.

 

Have you checked your coolant level? Low coolant gets low enough, it won't circulate through the heater core and you get no heat..... .....so its not hard to imagine, only a partial circulation of coolant might cause different performance once side to the other..... ....this is very typical of evaporators for AC, but the evaporator is evaporating the refrigerant in the evaporator, plus a leak at the evaporator, can really cause one side to be cooler than the other.... ....heater core, not as typical, but its possible....

It also costs nothing to check the coolant level and eliminate that as a possible cause.... ....check it properly, the O.M. tells you the wrong way to check coolant level, because of liability...... ...ONLY WHEN THE ENGINE IS COLD, open the pressure cap and make sure the coolant comes up to within an inch of the lip that seals against the pressure cap....
....idiots will open the radiator cap when the engine is hot, and if there is a malfunction or the engine is hotter than normal, they can burn themselves badly, and our current climate of liability, that means the manufacturer will get sued no matter how much they warn against it, so they just tell you not to do it......