Sqeaky on start up

[Bernieoh]

Hey all,

When I turn on the car with the air con on and for the first minute of driving I get a high pitched squeal. Very loud and I can't tell where it is coming from. Besides the engine.

With the air con off it barely makes a noise. Also if I drive for awhile and turn it off and then turn it back on again it doesn't make the noise. Only happens when it is off for an extended period.

any ideas what could be happening?

[WeeYari]

It is the serpentine belt. It either needs to be re-tensioned or replaced.

[Bernieoh]

I replaced it. What does re-tensioning it involve?

[WeeYari]

Loosening top alternator mounting bolt and sliding alternator a small amount toward front of vehicle. All new belts will stretch and subsequently need to be tensioned again.

[dogsridewith]

Serpentine belt puts load on a lot of bearings I don't want to have to replace.
I have tension where it just made a bird chirp on some cold starts on some cold mornings. (Now it is warm. No chirps.) Match marked the alternator and top bracket so I could see what a change was. Had trouble moving alternator...lower bolt was so tight I had to loosen that first. (What the manual instructs, but rarely you see a car w/ this bolt so tight.)
(Shop will have to tighten more than the particular owner...makes money replacing bearings, and gets hassled if something squeals.)

[Jboss]

Accessory belt i'm pretty sure.

[B.B._07]

It's the serpentine belt most likely. The belt is slipping a little with the extra load when started with the AC on, and it goes away with a warm engine at start up since the belt has contracted a little due to the heat. In my experience you need to use a bry bar or large screwdriver to pry between the engine block and the alternator to get the proper tension so the cold engine start squeak goes away. I wouldn't be too worried about damaging bearings, I've changed the serpentine belt on a very similar 1.8L Toyota 1ZZ engine which has an auto tensioner and I can assure you it puts a lot of tension on the belt.

[KCALB SIRAY]

It's a 2007 so the inner bearings of the AC are a good contender, not the belt slipping as my bearings just went recently with the exact same description the OP described. Don't rule it out, check both because you live in Dubai which easily can work in small granules of sand into the compressor to the inner bearings over time. I live in an area where road salts are used heavily and this caused my issue in my AC bearings over time.

[dogsridewith]

(Load free start and shutdown)
A commercial vehicle fleet owner once told me he turned everything off before the motor of a vehicle to reduce surge/spike in the alternator/charging circuit. So, it would also be off when starting up. So, there would also be lower belt load at startup in the alternator and A/C compressor.
(noting--in the traditional ignition, spark happens when a current carrying switch is opened...regarding why it might matter to electrical stuff at shutdown.)