Volkswagen Polo heater only blows hot air

Could be fresh/ recirculating air flap positioning motor knackered.

check the temperature control valve on heater box is not stuck,check all cables are on securely

Further info from polo site ,

know i've had trouble with my heating on my 02 1.4 TDi polo, tonight on my way home I was being blasted with boiling hot air ... had to open the windows!

My boyfriend has VAG-COM and did fault code check on the climate unit and it came up with what's below :

VAG-COM Version: Release 409.1-US

Control Module Part Number: 6Q0 820 045
Component and/or Version: Klimaanlage X0840
Software Coding:
Work Shop Code:
3 Faults Found:
01271 - Positioning Motor for Temperature Flap (V68)
30-10 - Open or Short to B+ - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
29-10 - Short to Ground - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
28-10 - Short to B+ - Intermittent

I've had a similar problem with hot and cold air blowing at the wrong time for the last few years on my 2002 polo, and eventually took the car to a very helpful Ali at Hornsey Motor Services, London N4 3BB. He got in touch with VW for info, and also told me that over time the plastic parts and circuit boards buried right inside the dashboard get over-heated and stop working properly. VW have now modified the parts apparently, and Ali had to replace the following: (1) "Heater Control Motor for cold and hot" at £98.58; (2) "Heater air flaps and rod" for about £10. The fan was also not working on the first setting so he also replaced the "Heater resistor" to put this right. Labour was £330 because of having to remove the whole dasboard, so it's not a cheap fix, but worth it for more comfortable driving