I have a set of "factory" fans from an 05 yukon i got from a junkyard....high amp draw problem. Got a new set of Dorman fans from rockauto and the draw was not as bad..i think the factory fans were worn out..
The relays burn up because we don't have proper control of the fans in the older model trucks. Not sure it's a problem in the 03+ trucks. Trucks with factory ac don't cycle the fans with the compressor, they work on ac pressure and don't have the constant high load and can actually cycle on low.
OK, so I called Dorman today. Since both the 620653 and 620654 will both bolt in to these trucks, I wanted to know what the difference was.
Apparently, the 620653 replaces the factory 5 and 7 blade fans. The 620654 replaces the 7 and 9 blade fans. The fan blades are the all the same on the Dorman replacements, but the 620654 spins at a higher RPM than the 620653 does to compensate for the fan blade count.
It looks like the 620654 has different motors than the 53 to spin the blades faster. This would explain the increase in amp draw with the 620654 units.
Now I just need to figure out which one I want for my '03 Yukon. The 54 would probably cool better, but may be more noisy. Probably should run a bigger alternator with that one, but still not sure if it would cause wiring or relay issues.
The 620653 should draw less amps, but don't know how well it will cool my rig when towing or running in really hot weather.
Why can't it just be simple....?
