Heat on one side not the other would not be a heater core issue, but a flapper/diverter valve issue somewhere.rguzz wrote:Thanks for all the info. New to the forum but peeked at my heater core which is original Volvo and yellowed. Not leaking. Heat does not come from all vents, only drivers side? so if lucky new core might improve this, though sounds more like a mechanical flap issue somewhere. Plan to follow DIY Robert's pointers, and will try the Swedish Car Parts replacement. Lots of good info on how to DIY on this one.
Do your HVAC lights flash on startup?






