7 Signs of AC Pulley Issues

Problems in your vehicle's air conditioning pulley can cause different disturbances. The main sign of AC pulley issues is a lack of cooling when turning on the air conditioner.

The AC pulley works with the air conditioner's compressor and the serpentine belt, and it can go bad for different reasons. Typically, whenever the compressor or serpentine belt develops an issue, it'll affect the pulley, damaging it and causing many symptoms.

• Key function: The pulley's key function is to transfer power. It rotates through the serpentine belt while the vehicle is running, generating rotational power. Consequently, power goes to the AC compressor, feeding the entire system and making the air conditioner work.

A faulty AC pulley won't transfer power to the compressor, resulting in an air conditioner that doesn't work. This can not only impact comfort but also be an issue when driving the vehicle.

• Safety: Air conditioners have a vital feature that helps drivers see during cold weather when the windshield gets foggy or frozen, the defrost. Therefore, a malfunctioning AC won't help drivers with a foggy windshield, leaving them with bad visibility. Additionally, a faulty AC pulley can cause issues in the serpentine belt, resulting in numerous electrical failures, a faulty power steering pump, water pump issues, engine overheating, etc. 

AC not cooling

Since the air conditioning pulley is rotating and powering the entire AC system, if it fails, the power stops. If the AC system stops receiving power, it won't blow cold air anymore.

Inside the vehicle's cabin, the temperature won't lower. The AC unit will be unresponsive and components won't work due to no power.

Alternatively, depending on damage, the pulley might transfer power but below what's needed for the AC to work properly. In this case, the cooling efficiency is compromised and won't lower the temperature noticeably.

Burning rubber smell

An issue in the AC pulley can also mean issues in the serpentine belt and compressor clutch, which involve rubber material. For example, the serpentine belt might have slipped out of place, damaging the pulley. In this case, the belt can flap under the hood and rub against hot engine components, melting and causing a burning rubber smell.

Alternatively, the pulley itself can develop an overheating problem, transferring too much heat to the compressor clutch. The clutch can start to melt over extreme temperatures and release a burning rubber smell.

Other signs

Here are some other signs that a faulty AC pulley can show:

• Grinding noises
• Intermittent AC
• Vibrations
• Electrical issues
• Squealing when engaging the AC

Possible fixes

• AC control unit replacement: If the AC pulley fails, it can cause the AC compressor to malfunction, disrupting the regulation of the refrigerant and causing the AC control unit to fail, requiring replacement.
• HVAC control replacement: A faulty AC pulley can lead to the AC compressor failing, resulting in poor refrigerant circulation. This can prevent the HVAC control system from maintaining the desired temperature, necessitating its replacement.
• AC compressor replacement: When the AC pulley is damaged, it can prevent the AC compressor from circulating refrigerant properly, causing the compressor to overheat and seize, leading to the need to replace the entire compressor.
• AC condenser replacement: A failing AC pulley can cause the AC compressor to malfunction, leading to incorrect refrigerant flow. This can cause the AC condenser to overheat and become damaged, thus requiring replacement.
• AC control module replacement: If the AC pulley fails, it can result in the AC compressor malfunctioning, causing inaccurate refrigerant regulation and leading to the AC control module failing and needing replacement.
• AC pressure switch replacement: A malfunctioning AC pulley can cause the AC compressor to provide incorrect pressure readings, leading to the AC pressure switch failing and necessitating its replacement.
• AC hose replacement: A damaged AC compressor can create excessive pressure or cause refrigerant leaks, which may damage the AC hoses and require replacement to ensure the system can hold refrigerant properly.
• Serpentine Belt Replacement: A damaged AC pulley can lead to excessive pressure or refrigerant leaks due to a malfunctioning AC compressor. This can damage the AC hoses, requiring replacement to ensure the system holds refrigerant properly.

Frequently Asked Questions

Can you drive with a bad AC compressor pulley?

In a pinch, you might be able to drive with a bad AC compressor clutch pulley, especially if it's not seized and spins freely. However, it's risky. A broken pulley can damage the belt, expansion valve, clutch coil, pulley bearing, potentially leading to overheating or even seizing the compressor itself, causing a cascade of expensive repairs. It's best to get it checked by a mechanic as soon as possible.

Can you bypass the AC pulley?

Bypassing the AC pulley is possible in some cars, typically by installing a special bypass pulley or using a shorter belt. This lets the engine run without engaging the AC compressor. However, it's a temporary solution at best. While it can restore some lost engine power and free you from belt worries, it completely disables your air conditioning and might cause warning lights. Consulting a mechanic for a proper air conditioning system repair is the safer and more long-term solution.

Why is my AC compressor pulley squealing?

The squeal from a bad compressor pulley likely points to a slipping issue caused by either a worn or loose belt or a failing component within the pulley itself. A worn belt loses grip, while a loose belt needs tightening. The pulley's bearing might be failing due to age or lack of lubrication, causing friction and noise. In some cases, the compressor clutch itself could be malfunctioning.