Air con and fuel usage

[TaylorGTi]

Does anyone get less mpg using aircon?

It never made a difference in my past car (123d coupe) and was curious as my air cons broke so can't find out for my self 

[bacillus]

I usually see a 1-2mpg difference...

[homesqueeze]

I usually see a 1-2mpg difference...

Same here, the difference is negligible.

[h45gti]

once I get mine fixed ill know   trying to fix it my self first before I take it to a garage to resolve, bought a pressure switch, getting the correct spanner tomorrow, hmm diesel and aircon and then petrol and aircon,.. shouldn't be much of a difference? aircon in a diesel probably use less fuel?

EDIT: less fuel to run the aircon

[OSB]

It used to be a 'rule of thumb' that aircons made fuel consumption worse by around 10%.
As improved compressor designs  have made them more efficient, it's probably more like 5% these days.
Anything that the engine has to drive, whether it's a aircon compressor, an alternator, power steering pump (ok I know we haven't got those!) etc., will add a load and increase fuel consumption by a small amount.

[J400uk]

Only slight but it's definitely noticeable especially on a hot day when the system is working hard

[cobz]

This is something I have tried to test myself... not the best conditions but I have definitely noticed 1 or 2 mpg less with it running. I just prefer to leave the window open.. can hear my car better that way