Why is my car's air con not cold?
A low gas level is the usual cause, but it can be a leak, the compressor or a blocked filter.
The short answerThe most common cause is a low refrigerant level from a slow leak. Other causes are a failed compressor, a blocked condenser, a broken cooling fan or a clogged cabin filter. A workshop can test the system and tell you which.
Quick checks
- Is the air con button on, with the fan up and set to cold? Is it recirculating air?
- Is the cabin filter dirty? A clogged filter weakens airflow.
- Does the air get cold at speed but warm when stopped? That can point to a cooling fan.
Likely causes
- Low refrigerant: air con systems are sealed, so low gas usually means a leak.
- Compressor problem: a noise, or the compressor never switching on.
- Blocked condenser at the front of the car.
- Electrical fault such as a blown fuse or relay.
Is a regas enough?
A regas refills the gas, but if there is a leak it will fade again. Ask the workshop to test for leaks and give you a written quote before any work.
Ask for a quote
Use Get written quotes to ask shops near you, and see Is my quote fair?.
Questions drivers ask
How often should I regas my car's air con?
There is no fixed interval. If it still blows cold, leave it. If it weakens, get it tested for a leak.
Is it safe to use a DIY regas can?
They can overfill or miss the real fault, and the system holds a regulated gas. A workshop test is a safer start.
Why does my air con smell?
Often mould in the evaporator or a dirty cabin filter. A clean and a new filter often helps.
Checked by AutoPlace editorial team. General information, not professional advice. Updated 15 October 2026.