Picked up 2010 Ford KA for daughter and heating blows cold until you crank up the fan speed and their is a "pop" sound under the dash that suggests a plastic valve opens and allows hot air to enter the cabin. Suggests that this valve is sticking and just needs a blast of air to release this. This is a pain as it does need a few efforts at times to get this flap open - no good for my daughter when she is without a clear windscreen!! Can anyone confirm what this is and how it can be simply resolved.

I thought at first it could be the heater control valve, but I don't see how increasing the fan speed frees it off.

Other thing I can think of is the blend door is getting stuck, and is probably an actuator failure. Couldn't tell you where they are located on a KA though.

Thanks for your reply. Hopefully someone knows where the actuator failure is or it's off to the local ford dealer.

it could be the heater control valve

HI 

Did you find the problem to this 

I have the same model and problem

thanks 

mike