Low refrigerant
Air conditioning is a sealed system, so low refrigerant means a leak somewhere. A regas restores cooling, but if the leak is not found, the cooling fades again.
Electrical and compressor faults
A failed compressor clutch, relay, fuse or pressure switch can stop the compressor engaging. Listen for a click under the bonnet when you switch the A/C on.
Airflow problems
If the air is cold but weak, a blocked cabin filter or a failing blower motor is more likely. A musty smell also points to the cabin filter or evaporator.
What to tell the technician
Whether the air is warm or just weak, whether it cooled after the last regas and for how long, any noises when the A/C is on, and the vehicle year (it affects which refrigerant is used).
Safe to drive?
Safe to drive. A working A/C does help demist the windscreen, so get it fixed before winter if you rely on it.
General guidance only, not a diagnosis. If in doubt, do not drive it and have it inspected. In an emergency, call 111.
Who can help
Get quotes for car air conditioning repair near you
Questions
How often should car air con be regassed?
A sealed system should not need regular regassing. Repeated loss means a leak that should be found.
Is it costly to fix?
It depends on the cause. A leak test and regas is a common starting point; ask for an itemised quote.