HI, I have a mk5 fiesta, im not getting any hot air, it blows warmish for about 10 seconds then goes cold, both pipes on HCV are warm/hot, the bottom rad hose is warm, and thermostat opening, fan kicking in etc...im stuck!
2nd problem when I start the car, I can hear a little whining/rubbing noise, sounds like a pump or something, then when I press the clutch down the noise goes?
The heater may have a bypass valve, when the water temprature drops below a certain theshold it may bypass the heater matrix, the low atmospheric tempratures may mean the engine is overcooled and you are taking too much heat out of the system
try giving the engine more time to warm up and use a lower fan setting
If there is even a slight problem, the cold weather can "magnify" it
is the temp gauge lower/ higher? ,
Alternatively you could have an air lock/ some Ford engines have a 2nd thermostat
is the coolant level ok and the car otherwise running ok?