just had the belts changed and at start up when a/c engages loud squeal. switch to econ and it stops- no noise after warm-up. sprayed with wd40 no real help- ?

 

The belt(s) made need to be re-tightened. When I put my UR pulley on, one of my belts wasn't tight enough and it would squeak when I first started the car. After warming it up a few minutes, it was fine. I just retightened the tensioner bolts/screws it it was fine. It does still for a split second when I start the car in the real cold temps, but Nissan told me it was because the pulley was too small for the tensioner to tighten the belts any more than they did. Don't know if that's the true answer or not, but it doesn't matter to me since the belt does it rarely now.

 

WD40 is a lubricant which would make it slip even more. Use belt dressing next time. New belts should not need to be sprayed with anything at all it there installed correctly.