Why does the brake become harder when the air conditioning is turned on in a Cruze?
2 Answers
The reason why the brake becomes harder when the air conditioning is turned on in a Cruze may be due to some malfunction in the engine control system's air conditioning idle speed boost device. This prevents the intake manifold behind the throttle from providing normal vacuum, leading to reduced braking effectiveness and making the driver feel that the brake has become harder. Below is some relevant information about the 2018 Cruze Redline 320 Automatic Pioneer Edition: 1. Powertrain: Equipped with a 1.5L naturally aspirated 4-cylinder L3G engine, paired with a 6-speed automatic manual transmission. 2. Body Dimensions: The length, width, and height are 4666mm, 1807mm, and 1460mm respectively. The wheelbase is 2700mm. 3. Chassis: The drivetrain is front-engine, front-wheel drive. The front suspension is a MacPherson independent suspension, and the rear suspension is a torsion beam non-independent suspension.
I also experienced the issue of the brakes becoming harder when the A/C was on in my Cruze. I remember that time on the highway in summer with the A/C running, the brake pedal suddenly became very stiff, and I almost couldn't stop in time. Later, when I had it checked by a mechanic, it turned out to be a problem with the vacuum booster system. Car brakes primarily rely on vacuum assist to function. Normally, the engine generates vacuum, but when the A/C compressor kicks in, the engine load increases, leading to insufficient vacuum supply and reduced booster performance. This is especially noticeable at low RPMs, such as when running the A/C in stop-and-go traffic. My mechanic mentioned that the vacuum hose in the Cruze had aged a bit and was prone to leaks. Replacing the hose fixed the issue. I recommend paying attention to how the brakes respond when the A/C is on. If they consistently feel harder, don’t ignore it—get it checked immediately to avoid more serious safety risks. Additionally, having the vacuum hose and booster inspected during regular maintenance can help prevent such problems.
