How much extra fuel will be used if I run the air con full time?

General advice seems to be to run a car's air con continually. How much extra fuel will this use?

Asked on 23 April 2021 by stephen heath

Answered by Dan Powell
On a long journey, less than 5%. On short trips in the summer, up to 10% (as the system is worked quite hard on a short journey as there isn't the necessary airflow assisting it). You can cut the above figures when the weather is warm by opening the windows by 1/3 and directing the cold air to footwells for a few minutes (this will force the hot air out of the windows).

Either way, spending a few extra pounds on fuel is more cost-effective than regassing your AC and/or replacing the compressor. The AC system is self-lubricating. Switching it off for three or four months will cause the seals to dry out and starve the compressor of oil.
Tags: air con
Similar questions
Is it true that you should have your recirculation button on all the time in summer when you are running the air conditioning?
How often should the aircon be serviced on my car?
I had followed your advice to always keep the air con switched on, and to good effect in that with my vehicle owned from new for 20 years it has always worked fine without ever even needing re-gassing....