Why Does the Car Air Conditioning Frequently Start and Stop?
3 Answers
Car air conditioning frequently starts and stops for the following reasons: Pressure aspects: When the pressure in the air conditioning system exceeds 24 BAR or falls below 2.4 BAR, the pressure switch controls the compressor to shut down. Power aspects: When the engine power is insufficient, the engine ECU controls the compressor to stop working via the 822 relay. Engine coolant temperature aspects: When the coolant temperature is too high, the temperature control box controls the compressor to stop working via the 805 relay. Evaporator temperature and control aspects: When the evaporator temperature reaches 1 degree, the compressor stops working; it starts working again when the temperature reaches 3 degrees.
Over the years of countless car repairs, I've encountered many cases of frequent air conditioning cycling. Common causes include a faulty thermostat that oversensitively switches the compressor on and off, causing intermittent operation. Or insufficient refrigerant leading to unstable system pressure, triggering the automatic protection mechanism to cycle the system. Worn compressor clutch is another issue, failing to maintain stable engagement and resulting in inconsistent cooling. Electrical problems like faulty relays or control modules sending erratic signals also contribute. Regular checks of cabin air filters and refrigerant levels can prevent issues. Additionally, AC systems cycle more frequently in extremely high ambient temperatures, especially during peak summer heat. Routine maintenance is crucial—don't wait until problems escalate.
My old car's air conditioning keeps turning on and off like this, which is quite annoying to drive with. I think the set temperature might be too high, causing the system to repeatedly adjust to save energy. Or maybe the fan is running too strong, putting a heavy load on the system and making it unstable. Refrigerant leaks can also cause significant pressure fluctuations, making the on-off cycles faster. I tried replacing the thermostat myself before, but it didn't work well. A professional check later revealed it was a faulty pressure switch. It's recommended to keep good ventilation inside the car and set the temperature and fan speed reasonably. Avoid using the recirculation mode for too long, as this can make the system work more frequently. In short, it's better to go to a repair shop early for a check-up to save trouble.
