What to Do When the Brakes Become Hard with Air Conditioning On?
2 Answers
If the brakes become hard and the pedal is difficult to press when the air conditioning is on, there may be an issue with the brake vacuum system. In such cases, the vehicle should be sent to a 4S shop for repair as soon as possible. Below is the relevant explanation: 1. Increased engine load: Generally, when pressing the brake pedal, the accelerator pedal should be released. At this time, the engine speed remains high due to the vehicle's inertia, while the throttle is nearly closed. Therefore, the vacuum level in the intake manifold is at its highest, providing the best braking effect. However, when the air conditioning is on, the engine load increases. To prevent a decline in the vehicle's power performance, the engine control system is usually equipped with an air conditioning idle speed boost device. 2. Throttle unable to provide vacuum: In carburetor and low-end electronically controlled fuel injection engines, this device slightly opens the throttle through an electromagnetic or vacuum suction package. Therefore, even when the driver releases the accelerator pedal during braking, the throttle remains slightly open. Under these conditions, the intake manifold behind the throttle cannot provide the normal vacuum level, resulting in a correspondingly poorer braking effect.
I encountered this situation last time when I took my family out for a drive. After turning on the air conditioning, the brakes became stiff and harder to press. Later, the mechanic at the repair shop explained that this happens because when the air conditioning is turned on, the engine load increases, causing the vacuum level in the vacuum booster to drop. The brakes rely heavily on this vacuum booster, and once the vacuum level is insufficient, the pedal becomes harder to press. It's recommended to first check if there are any leaks or blockages in the vacuum hose and one-way valve, as leaks in these areas most affect the vacuum level. You should also check the working condition of the brake booster pump. I later replaced a leaking hose, and the problem was resolved. If you encounter this situation on the road, drive directly to a repair shop for inspection—brake issues should never be delayed.
