[b][i][#0000ff]I am replacing a power supply on an HP Pavilion for a friend. It was completely dead and I assumed it was the power supply. I received the replacement and plugged it in...nothing. However, when just plugging the power supply into an outlet, the fan does not come on. The green light does, but very slowly and dimly. Is this correct? Shouldn't the fan come on immediately upon plugging it into an outlet?

No, often the PSU fan will not run unless it is required to cool the PSU.
It depends on a number of factors if the PSU will be that smart.

OK - thank you. All of the ones that I had experience with before had a switch on them and when turned on, the fan would spin. I appreciate your quick reply.

in most cases the fans on a PSU only run when the computer itself is on. Normally when the PSU is plugged in and the computer is off it is only supplying a very small amount of power to the board for turning on the system and some other various small power requiring tasks. Generally the amount of power required for these tasks isn't enough to make the PSU to generate the amount of heat that would require a fan.

If the psu is dead, hope that it didn't take down any components with it. The fan usually runs at low or not at all, if it isn't warm.