Have a 2008 with 23,000 miles on it. Recently, I noticed that there is a low-frequency noise (squeal?) that lasts for several seconds when turning the air conditioner on or off. I'm wondering if there's insufficient tension on the serpentine belt or if it might indicate a problem in the A/C compressor. Am also thinking about spraying some Belt Dressing on the belt (inside & outside) to see if that corrects the problem. Any thoughts?
Diagrams that I've seen show the serpentine belt going around the compressor pulley. Not sure why that would even be necessary, since there is a HV motor inside the compressor.
Just trying to understand the problem and possibly avoid a trip to the dealer. If it's a matter of adjusting belt tension, that may not be covered under warranty.
The 2G has a serpentine belt whose only function is to spin the engine coolant pump. If you still doubt this, it is very easy to open the hood, look for the air conditioner compressor, and note that there is no pulley attached to the end of the compressor. Since your car is still covered by the 3 year / 36K mile warranty, it would be a good idea to visit your Toyota dealer soon, assuming that the AC noise can be demonstrated upon demand. If the noise is intermittent perhaps you might record the sound. Good luck.
Patrick, Just popped the hood and, as you indicated, there is no pulley on the A/C compressor. The serpentine belt goes around the crank pulley, coolant pump and idler pulley only. The diagram on the Internet, which showed the belt going around the compressor pulley, is obviously wrong! The noise is repeatable, which is a good thing. I'll let the Toyota dealer handle the problem.
Perhaps the diagram that you saw was related to Classic Prius, where the AC compressor is belt-driven.
UPDATE..... The 3-year warranty was almost up and the wife reluctantly let me take her '08 Prius in to have the noise (moaning sound) @ A/C turn on/off investigated. The dealer (Longo Toyota in El Monte, CA) did a great job diagnosing and making the required repairs. Two servo motors that control the vents were the culprits and were replaced. It was a very involved job that required removal of the dash to gain access. Labor was 5.1 hours! The master tech said that this is the first time they ever encountered this kind of problem. Had them also look into the "barking seal" noise when the brakes are applied. They were able to bleed the brake system several times and correct the problem without brake actuator replacement. The brakes now operate smoother than when the car was new. Kudos to the Longo Toyota Service department for a job well done!
