AC Not Blowing Cold

What's happening

Most likely causes

1. 1

   Low refrigerant from a slow leak

   The top cause. Refrigerant doesn't get used up; low means leaking.

2. 2

   Failed compressor clutch

   The compressor isn't engaging; no cold air at all.

3. 3

   Blocked condenser

   Debris or bent fins stop heat rejection.

4. 4

   Blend door stuck on heat

   The AC works but hot air mixes in; temperature won't change with the knob.

How to diagnose it — in order

1. 1

   With AC on max, check if the compressor clutch engages (click and spinning center).

2. 2

   Feel the two AC lines: one should be cold, one hot.

3. 3

   Look for oily residue at AC fittings; that's leaking refrigerant oil.

4. 4

   Check the cabin air filter; a clogged one strangles airflow and feels like weak AC.