I haven't had a chance to sit down and properly diagnose this yet but when I set both the driver's & passenger (RHD) side climate controls to maximum heat (28 celsius) only the passenger side gets heated air. The driver's side simply doesn't. I'm thinking it's most likely either a U/S driver's side heater valve or lack of power to it. Also, are there one or two auxiliary coolant pumps supplying the heater core?

TIA - Cheers