Hi all, my Air con pump cycles on/off continuously, noticed this while warming the car up to attempt bleeding the cooling system, so heater was on hot.
it cycles at about 5s on/off. any ideas?


the air does get cold normally although I get hot air out of the top and dash vents when driving - cold at feet - I reckon that's another issue

 

1990 built marelli V12

 

Some cycling is normal either in response to system pressures or to the icing switch that cuts the circuit if the evaporator start to ice up.

Every 5 seconds doesn't sound quite right, though. Might be slightly low on Freon. I'd have the hi-lo pressures checked.

Cheers
DD

 

Short cycling is a sign of being undercharged. As Doug mentioned, have the pressures / weight of refrigerant in the system checked.