Old mechinic always told use that pumping with the air on was very bad for pump caused all sort of problems for him, never explained hiself.  The only thing i figure is that if the belt broke it would trow it to the main belt and break it also. But was he right does it cause more problems or did he just like to see use sweat while he worked in the air condiction shop????

I was always told the same thing,it has been brought over the years,it is to keep the engine running cooler,belts,harder on the engine,takes up horsepower,R.P.M.. Take your choice,but if you aint using it why run it?

i was told runs commpresser all the time and if stops it will break the belt then break the main belt .

I pump with it off, like he said if you arent using it why have it on. flip it on around the last couple trucks.

IF YOU HAVE AN OLDER TRUCK WITH A VISCIUS FAN, IT WILL NOT BE ABLE TO SENSE THE HEAT BUILD UP IN THE CONDENSOR , AND CAUSE THE REFRIGERANT TO OVERHEAT

WHEN THIS HAPPENS THE REFRIGERANT IS VENTED AND YOU HAVE NO A/C FOR THE RIDE HOME.

NEWER TRUCKS WITH ELECTRIC CLUCTHES. DON'T HAVE THIS PROBLEM. BUT YOU STILL HAVE LESS POWER, MORE FUEL CONSUMPTION, ETC.

just a bunch of bull.it takes more power to pull/drive pump up hills,stop and go than it takes to pump concrete.look at your tach when driveing and pumping, a noticeable difference.if belts show signs of wear replace it,belts brake thats life.besides mythbusters had an episode on this past fall that busted the myth that ac uses alot more fuel/gas to run,it was in the tenths of per gallon,as far as horsepower sit in truck and watch tach and turn on and off ac not to much difference.so what if fan kicks in tenthosandts of second sonner than with it off.just bull. 

When I was trained on REED PUMP(GOOD INSTRUCTOR IN MARTIN RODRIGUEZ) Was told not to!!!  HARD ON ALTERNATOR!!!   REMOTES AND ALL NEED THE JUICE!!! Also know few around here that go thru a few alternators a year!!! THEY LEAVE AIR ON!!!