What is the reason for a loud abnormal noise when the car's AC is turned on?

[LaJude]

The reason for a loud abnormal noise when the car's AC is turned on is: The air conditioning compressor is driven by the engine crankshaft via a belt. If the belt becomes loose, aged, severely worn, or if the tensioner lacks sufficient tension, it can cause the belt to slip, resulting in a hissing noise. If the belt slipping is caused by the belt itself, simply replacing the belt will resolve the issue. However, if the problem lies with the tensioner, then the tensioner needs to be replaced. The reasons for unpleasant odors in a car's air conditioning system are as follows: 1. Accumulation of dust in the indoor filter and copper coils: After prolonged use, dust can accumulate in the indoor filter and copper coils, and when this reaches a certain level, it can produce an odor. When the AC is turned on, this odor is dispersed into the air. 2. Moisture inside the indoor unit: After the air conditioning operates in cooling or heating mode, moisture often remains inside the indoor unit. If the AC is turned off immediately without a drying or anti-mold function, this moisture persists, leading to the growth of mold over time, which naturally produces a musty smell.

[MackenzieFitz]

I just encountered a similar issue where my car makes loud abnormal noises when the AC is turned on, such as roaring or squeaking sounds. Here are a few common causes: The compressor might be worn out or lack lubrication, and if its bearings are aged, it can produce friction noises upon startup; loose or cracked belts can also squeak, especially in older cars where belts tend to deteriorate; issues with the fan system, such as debris stuck in the blades or motor failure, can cause rotational noise; insufficient refrigerant can overload the compressor, leading to abnormal sounds. For a preliminary check, start the car and let the engine idle, then open the hood to listen for the source of the noise, inspect the belts for cracks or looseness, and check if the fan blades are clean. Ignoring these issues can accelerate compressor failure and affect the lifespan of the entire AC system, so it's advisable to visit a professional repair shop as soon as possible for a thorough inspection and repair.

[McMolly]

Over years of driving, I've encountered strange noises from the AC. Noise when turning on the AC is usually caused by compressor or belt issues. If the compressor's bearings are damaged while working, it produces a friction roar, especially under high load. Worn or loose belts can cause a squealing sound, particularly noticeable when turning or accelerating. Deformed fan blades or accumulated dust spinning can also create noise. Refrigerant leaks make the compressor labor and produce noise. Ignoring it long-term may lead to belt breakage, cooling failure, and the AC not cooling while consuming more fuel. A simple DIY is to check the belt tension by gently pressing to see if it's elastic, and clean debris from the fan area, but this issue is complex and safer to consult a technician.

[Ibarra]

Air conditioning noise is mostly caused by AC system failure, compressor bearing or clutch wear, belt aging, or abnormal fan motor. A loose belt squeals, lack of oil in the compressor causes a rumbling sound, debris stuck in the fan blades creates noise, and insufficient refrigerant increases load and generates noise. These issues will worsen if not addressed promptly. Early detection by listening to the sound location and visually inspecting belts and fans can save on repair costs.

[DelVivian]

The car makes a loud noise when the AC is on, which should not be ignored. It could be caused by compressor wear, a cracked belt, or a faulty fan. For example, a damaged compressor bearing causes friction, a loose belt slips and squeals, or a stuck fan blade produces a knocking sound. This can reduce the effectiveness of the air conditioning and even affect engine cooling. It is recommended to turn off the AC while driving, pull over to check basic components for safety first, and leave the repairs to a professional shop for reliability.

[MorganDella]

Abnormal noises when the air conditioning is on are commonly caused by wear of the compressor clutch, loose belts, or fan issues. Aging compressors and bearings may produce a rumbling sound, while loose belts create more noticeable squeaks, and faulty fan motors can cause a buzzing noise. Insufficient refrigerant increases the load, leading to louder abnormal noises. Daily preventive measures include regularly checking the belt condition and cleaning dust from the condenser and fan area, which can extend the system's lifespan. Abnormal noises serve as warning signals; addressing them early can save the cost of replacing the entire unit.