Why is my car AC not blowing cold air?

Car AC that blows warm or only mildly cool air is almost always low on refrigerant due to a small leak. Other causes include a failed compressor, a stuck blend door, a clogged cabin air filter, or a blown fuse on the AC clutch circuit.

Cost range: $30–$1,500. Severity: low. Safe to drive? Yes — comfort issue, not a safety issue (unless visibility is also affected by a fogged windshield).

Most likely causes

1. Low refrigerant from a leak — Most common by far. A DIY recharge can confirm the system but won't fix the leak — and overcharging damages the compressor. ($150–$600, common)
2. Failed AC compressor — Listen for the clutch clicking on. If it never engages, suspect the compressor, clutch, or low-pressure cutoff. ($700–$1,500, common)
3. Clogged cabin air filter — Reduces airflow but air is still cold. Filter is usually behind the glove box. $20 DIY in 5 minutes. ($20–$60, common)
4. Stuck blend door actuator — Clicking sound from behind the dash, or temperature only changes on one side. Common failure on many GM and Ford vehicles. ($150–$600, less common)
5. Blown AC fuse or relay — Cheapest thing to check first. Fuse box diagram is in the owner's manual. ($1–$30, less common)