My 91 SWB Pajero recently developed a screeching noise which starts when you accelerate at around 900RPM, get extremely loud at about 1500 RPM, then disappears at 2000 RPM. Can't seem to pinpoint the source exactly but it seems to come from the front of the engine compartment- fan area. It's worse when you're first starting out.

Engine performance is fine otherwise. Truck has 80K clicks. Still on original timing belts AFAIK.

The exterior belts seem fine tension-wise- some play when you push on them but not much.

Now here's the puzzler - the noise disappears completely if the heat/cool interior fan switch is turned off!

The heater/AC door is in need of alignment or adjustment - one vent puts out cold while the other doesn't when running the AC, for instance, but i'm not sure if this is related to the noise.

Is there a clutch on the main engine fan which is activated when you turn the blower on? There's a fan belt so I can't see how this would work, but...

one more bit of information - the truck has a turbo timer (?) which is supposed to keep the engine on for a count down period when you shut down - but it only has worked when I had the shift console off trying to adjust the starter neutral safety switch. It will run the fan when the engine is not running for the countdown period , though.

Help!

its either the air con compressor belt or the clutch that connects it has seized..so when the engine is turning, the compressor is not able to turn thats when the belts screeches..with engine running try pouring water onto the belts see if it stops..

Thanks I'll have a closer look. The AC does work so I assume this means the clutch is a candidate.
I just found out last night that even with the heater fan turned off it screeches when first starting out. When it warms up- and over 2000 RPM- the noise goes away. it sometimes "chirps" briefly too when accelerating.

what's a good source for parts? - the advertisers on POCUK?