What is the reason for no air in car air conditioning gears 1, 2, and 3 but normal in gear 4?
2 Answers
The reason for no air in car air conditioning gears 1, 2, and 3 but normal in gear 4 is a faulty blower motor resistor. Here are the relevant details: 1. Purpose: When using air conditioning in summer, parked vehicles should first open the windows and set the blower to the highest gear to allow air convection inside the car, expelling hot air before closing the windows to achieve rapid cooling. 2. Startup load: When parking, turn off the air conditioning before shutting down the engine to avoid increasing the startup load. 3. Recirculation mode: Turn on recirculation mode when using air conditioning for optimal cooling effect. 4. Prolonged use: Avoid prolonged use of air conditioning when the vehicle is parked to prevent deterioration of air quality inside the car and potential health impacts.
I remember when the air conditioning in the car had no airflow at low speeds but worked normally at high speeds, it might be due to a faulty blower motor resistor. The blower motor resistor controls the fan speed for the first, second, and third settings—it acts like a regulator to prevent excessive current. The fourth setting usually bypasses this resistor and directly connects to the blower motor. The resistor operates under high temperatures for long periods, making its plastic components or internal wiring prone to melting or poor contact, which can cause the low-speed settings to stop working. When checking, you can first look at the car's fuse box to see if the fuse for the AC blower is blown—replacing a cheap fuse is an easy test. However, if the issue persists, it's best to have a professional mechanic test the resistor's voltage with a multimeter, as they can ensure the wiring isn’t loose. AC malfunctions not only affect comfort but can also cause the windshield to fog up, impairing visibility—so early intervention is crucial. I recommend car owners pay attention to regular system maintenance to prevent minor issues from becoming major problems.
