What are the reasons for the air conditioning compressor not starting?
4 Answers
There are several reasons why a car's air conditioning compressor may not start: severe internal wear of the compressor leading to inability to function properly; insufficient refrigerant (Freon) in the car's air conditioning system; circuit system malfunctions, etc. Additionally, factors such as insufficient refrigerant in the car's air conditioning compressor, relay failures, or tripped pressure switches can also prevent the car's air conditioning compressor from engaging. Extension: 1. Function of the air conditioning compressor: The car's air conditioning compressor is the heart of the car's air conditioning refrigeration system, responsible for compressing and transporting refrigerant vapor. Compressors can be divided into fixed displacement and variable displacement types. Based on different working principles, air conditioning compressors can be categorized into fixed displacement compressors and variable displacement compressors. 2. Technical classification: Compressors can generally be classified into reciprocating and rotary types. Common reciprocating compressors include crankshaft connecting rod type and axial piston type, while common rotary compressors include rotary vane type and scroll type.
What I fear most when driving in summer is having no air conditioning—it feels like I'm melting. If the AC compressor isn't working, don’t panic right away. First, check if the fuse is blown—it’s similar to a tripped circuit breaker at home, especially common during hot weather when the AC is running. Then, feel if the relay is overheating; when mine failed last time, there was no clicking sound when pressed. Also, inspect the wiring connectors to ensure they’re tight—a friend’s car recently had poor contact due to a loose plug. By the way, the AC needs enough refrigerant to function; if the pressure is too low, the compressor won’t start. Here’s a lesser-known tip: Some cars’ AC systems won’t work until the engine reaches operating temperature—try turning it on after the coolant warms up. If none of these checks solve the issue, it’s likely the compressor’s electromagnetic clutch is faulty, and you’ll need a mechanic to fix it.
I found many people think the A/C not cooling means the compressor is broken, but actually it's mostly simple issues. Last time my car's compressor wasn't working, I checked three things myself: open the hood and locate the fuse box, if the A/C fuse isn't burnt then continue checking. Then use a screwdriver to poke the relay to see if there's a clicking sound, no sound means it's stuck. Also check the electromagnetic clutch on the compressor pulley head for any wear marks. Once after washing the car, the belt got wet and slipped, causing the compressor to stop spinning directly. If the A/C suddenly stops cooling on rainy days, it's likely the pressure switch protection activated, it might fix itself after the rain stops. Wiring issues are actually the hardest to deal with, especially for cars with aftermarket navigation, pinched wires can also cause the compressor to cut off due to protection.
Having spent a long time in auto repair shops, I've seen a lot. When the compressor doesn't start, eight out of ten times it's a minor issue. The most common problem is refrigerant leakage. The pressure switch cuts off the power when it detects insufficient pressure, so of course the compressor won't run. Modern cars come with air conditioning pressure protection, and the central display might show a warning when Freon is low. Another issue is faulty temperature sensors; the engine computer might mistakenly think the temperature is too low and prevent the compressor from starting. Just the other day, a car needed repeated AC restarts to work—turned out the compressor's electromagnetic clutch had too much gap. Older cars especially need attention to belt tension; if it's too loose, you might hear the belt slip and squeal when the AC kicks in. Actually, it's quite common for high temperatures in the engine bay to accelerate wiring aging, particularly when oxidation increases resistance at the connectors.
