1. Low refrigerant, from a leak
An A/C system is sealed. It does not use up refrigerant the way an engine burns oil. If it is low, it leaked out. Common spots are the o rings at the line fittings, the condenser at the front of the car, the compressor shaft seal and the evaporator inside the dash.
A recharge will make it cold again. If there is a real leak, it will warm up again in weeks or months. The fix is to find and repair the leak, then charge the system.
2. The compressor is not engaging
The compressor is driven by the engine through a clutch. If the clutch does not engage, nothing gets cold. Causes include a failed clutch coil, a blown fuse or relay, or a pressure switch that stops the compressor because the refrigerant is too low. That last one is the car protecting itself.
3. A blocked or damaged condenser
The condenser sits in front of the radiator and gets hit by every stone and bit of salt on the road. If it is clogged with debris or holed by a stone, the A/C works on the highway and goes warm in traffic.
4. The cooling fan
At a standstill, the radiator fan has to pull air over the condenser. If the fan is weak or not running, you get cold air while moving and warm air at lights.
5. It is not the A/C at all
A blend door actuator decides whether air goes past the heater core. If it sticks on the hot side, the A/C can be working perfectly and you still get warm air. Often you will hear it clicking behind the dash.
About DIY recharge cans
We see a lot of systems that have had a can or two from the parts store. The problem is that many contain sealer, which can clog the small passages in the system, and it is easy to overfill without gauges. An overcharged system cools worse and strains the compressor.
What we charge
An A/C complete system charge at King’s is $175 before tax. Cars on the newer R1234yf refrigerant cost more, and we confirm that before we start. Air conditioning has been one of our specialties for a long time. More about A/C service or call (613) 745-0004.
