My car squeals when I start it or turn the AC on
A squeal from under the hood is usually the drive belt slipping on a pulley. The belt may be old and glazed, loose from a worn tensioner, or wet from a leak. That belt runs the alternator, the AC, and often the water pump, so if it breaks the car can overheat or die.
Urgency
This week is fine
What to do right now
What to do right now
- 1Note when it squeals: cold start, turning the wheel, AC on, or after driving through water.
- 2With the engine off, look at the belt for cracks, shiny sides, or missing chunks.
- 3Do not spray belt dressing on it. It hides the noise and can make the belt slip more.
- 4If the battery light or temperature gauge acts up, stop driving. The belt may be gone.
What it usually is
What it usually is
Starter and alternator
A slipping belt cannot spin the alternator well. We replace the belt and tensioner and check the alternator pulley and bearing.
See the servicePower steering
If it squeals when you turn the wheel, the power steering pump may be low on fluid or hard to turn.
See the serviceAC repair
A squeal only with the AC on can point to a compressor that is starting to seize or a clutch that is slipping.
See the serviceQuestions people ask
Why does my belt squeal after it rains?
Water on the belt makes it slip for a minute. That can be normal after driving through a flooded street. If it squeals every morning even when it is dry, the belt or tensioner is worn.
Is this my timing belt?
Probably not. The timing belt sits behind a cover and usually does not squeal. The one you hear is the drive belt on the front of the engine. We can tell you if your timing belt is due too.
How long can I drive with a squealing belt?
It is a warning, not a breakdown. Get it done this week. If the belt snaps, you can lose charging, AC, and sometimes cooling all at once.
Can I just tighten the belt?
Most newer cars use an automatic tensioner. If the belt is loose, the tensioner is usually worn and needs to be replaced along with the belt.