Nissan Repair: A/C 89 Nissan PU, groove belts, spray lubricant

Question
I am having a loud screech when I turn on the A/C.  When I first start the truck I can drive at a slow speed but once I speed up the screech starts. I turn off the A/C and it stops. I can then get the PU to a steady 30 mph or so turn the A/C on and there is no screech, but as soon as I give it more gas it starts again. I can stop the screech by turning off the A/C and then turning it back on, this works unless it is really hot or I have to stop at a light and then it starts over. How do I tighten the belt or can I use belt dressing. Can it be the compressor bearings. I can't find any adjustment for the belt. Thank you for any help.

Answer
Hi Ron -

Did not get the size of the engine, so I will give you generic instructions.

The belt is either too loose, or needs replacement. Do not use belt dressing, it makes it worse. In fact, using a little grease or spray lubricant on the belt will help, as that will soften the rubber.

Can you tell me if you have a serpentine belt, or separate V-groove belts? Serpentine belts have splines in them (about 4 or 5) only one belt, and it drives all components. These belts are non adjustable so the best thing is either use the lubricant, or replace the belt. If it is a V-groove, then you should have 3 belts. The adjustment is usually an intermediate pulley, or on the power steering I think. Follow the components that the A/C belt runs, and you will find it.

Hope this helps -
aloha
calvin