What Car? Q&A - Should I run air-con on cold in winter?

Q: I normally associate air-conditioning with keeping the car cool in summer. However, during the colder months, I sometimes use it with the heater to speed up demisting the windshield and windows. Does the air-con still function as normal when the heater is on, but only substituting warm air for cold air? Should I still run it on a cold setting during the cold months to avoid any damage to the system?
Murshed Islam

A: You're not doing any damage by using heat. Running your air-conditioning on hot to help demist your windscreen will dry out condensation in the system which can cause corrosion.

You should also, however, run on cold for five minutes a week at least, even through winter. This will drive lubricating refrigerant around the system and keep it ticking over.

Condensation and lack of lubrication are the two chief reasons an air-conditioning system can go wrong, so regularly run on hot and cold through the year and you'll be treating it very well.