Any idea what would cause intermittent high pitched noise coming from engine compartment. Just bought the car with 209k runs fine but check engine light just came on. No other lights or noises. Have owned 240,740,850 but never 960.
Seller told me ac compressor needs a new bearing, is this a tough job?
Thx

 

could be the belt but the compressor is likely. you need another compressor... not cheap!

 

Have you confirmed that it is really the a/c compressor? Does it make the noise when the a/c system is off?
You need to rule this out immediately. It could be a pulley in the timing belt train.

Other sources of whines, the alternator when charging a depleted battery, power steering pump.

What is the code on the check engine light, the a/c compressor would not trigger that.

DanR '94 964 387,000 miles (153,000 on the new engine)

 

Sorry as I am new to this and left out important info
Compressor is disconnected, the guy I bought it from connected it to show me it was the bearing which seemed to be making the noise and small amount of smoke when connected.

When I drove the car this morning fan off I did not hear the noise at all. Will drive it this afternoon and see if I get it in the heat with fan on or off

Car runs great but want to avoid a costly repair if possible.

The noise and the compressor are two separate issues. Sorry to waste your time with last post.

If you have suggestions on how to locate the noise I will try anything today and respond.
Thx

 

When the noise is on going, remove the serpentine belt, if the noise continues, then it most likely is in the timing belt, if it stops then the accessories. Turn the idler and tensioner pulleys and the alternator by hand to feel or listen for possible causes. A long screw driver held safely while the engine is idling against various components and with ones ear placed on the handle of the screw driver allow the sound to transmit thru the screw driver. That might be worth a try.

DanR

 

If the timing belt goes in 960 will it hurt the motor? I think the 740 were not affected by a torn timing belt but not sure. Dont't know if I should continue to drive it.

 

Yes, it most certainly will cause damage, to the valves at the least, some have had holes punched thru pistons, rare but possible.

Most likely it is in the accessory belt system, but you must eliminate the potential for the timing belt system first.

Another thing to look into, the HVAC system uses a slight vacuum to pass thru the thermostat in the dome light, sometimes with age the hose will collect some lint and start to clog, it can cause a whistling, very subtle but annoying, and it can vary with engine speed, but disappear with vehicle movement because it is not a loud whistle.

DanR

 

Would outside temp have an impact on the engine? It was really hot 90+ and humid the day I got the noise...have not been able to hear it since and temp is 75-80 now. There is a good Volvo shop nearby that charges 1 hr labor to do a full inspection. I might go that route to be safe if I can't get noise again.
Thx for your input and will let you know how I make out. Forgot how comfortable the seats are...was driving lexus 430 and this 960 feels better.

 

Temp change from 75 to 90 should not affect how engine runs.

Since you can't even take out the accessory belt, like Dan advised, I need to warn you that these cars and Repair shops don't mix very well, from a financial perspective.

 

Changed te accessory belt today and no noise from timing belt. Belt was easy to change and seems to be quite.
Thx

 

Check engine light was down stream o2 sensor. Does this have any impact on operation of the car?

Also, any experience replacing the bearing in the ac compressor? Reconnected it and it runs fine but the noise seems to right in front of the unit. Guy I bought from was sure it was the bearing and said he would replace it in a few weeks. Don't want to wait if I can do it now

Thx

 

Can anyone tell me how to figure which compressor I have in 1997 960. I don't see any marking anywhere... Found a bearing for SD7V16,SD7h15,TRS090
Thx

 

That's a Sanden SD7H15, 7-cylinder. It also needs 240 ml of lubricant. Looked it up at the Resources Sticky at the top.