Engine pulley stopping and starting while idling

2014 SUBARU CROSSTREK

34,000 MILES • 2.0L • 4 CYL • 4WD • AUTOMATIC

DEREKREID1980

MEMBER
2 POSTS

There is one pulley on the belt drive that starts and stops sporadically. at times it goes backward and makes a clunking noise when it starts or stops. is this normal?

Video (Click to enlarge)

Feb 10, 2019 at 1:57 PM

MPNANTO

✓Experienced Mechanic
17 POSTS

Hi Derek,

Thanks for visiting 2CarPros.

What you are looking at is your A/C clutch, it is normal for it to start and stop. The backwards rotation is also normal. The clutch engages to allow the compressor to spin this is what moves the refrigerant through your A/C system. When the A/C is not on the clutch disengages allowing the pulley to spin without moving the refrigerant through the system.

The backwards turn is the high and low sides equalizing. Once the clutch disengages the valve closes and the compressor vanes are pulled.

Feb 10, 2019 at 2:29 PM