Your broken A/C is a winter problem, not a summer one

Most people treat a broken air conditioner as a summer inconvenience they'll deal with next year. Then it rains for four months and they discover what the A/C compressor was actually doing.

Defrost runs the A/C

Put your car in defrost mode and, on almost every vehicle built in the last thirty years, the air conditioning compressor engages. Deliberately.

The A/C system's real job isn't cooling, it's removing water from air. Air passes over a cold evaporator, moisture condenses out and drains away, and what reaches your windshield is dry. Dry air clears fog. Warm wet air just moves it around.

So a car with no working A/C has no proper defrost. In August that's uncomfortable. In November in Pierce County, that's a visibility problem, which is a safety problem.

The symptoms, and what they usually mean

• Cool but not cold. Low refrigerant, which means a leak. Sealed systems don't consume refrigerant.
• Cold at speed, warm at idle. Airflow through the condenser. Usually a cooling fan not doing its job.
• Cold one side, warm the other. Blend door actuator. Small part, awkward location, entirely fixable.
• Weak airflow everywhere. Cabin filter, most of the time. People go years without changing one.
• Musty smell when it starts up. Blocked evaporator drain, water sitting where it shouldn't.
• Windshield fogs and won't clear. Compressor not engaging. This is the one to deal with now.

On recharge cans

The cans at the parts store will make it cold for a few weeks. They don't fix leaks. Most contain a sealer that's meant to plug small leaks and which can contaminate a recovery machine, so some shops will refuse to work on a system that's had it in.

If your system is low, it leaked. Find the leak or you'll pay for the same refrigerant again next year, and possibly for the damage the sealer did in between.

Get it done before October

A/C work is seasonal, which means it's quiet now and busy the moment it turns cold and everyone discovers their defrost doesn't work. Book it in the quiet part of the year and you'll wait days rather than weeks.

Here's what we check on an A/C and heating job.