My swap cooler needs a new motor has a 1/2 hp can I use a 1 hp as an upgrade?

Use a multi-speed 1/2 HP if they don't have the proper single speed frame size, then coil tap it for the proper RPM's.

They always have a muti-speed 1/2 HP replacement that will fit and coil tap to the needed RPM's on the fan shaft.

The same deal often on a 2 speed furnace blower, then you have to get a 3 speed motor and coil tap it for 2 speed.

I suggest you do not do this; the 1/2 hp appears to have worked; a higher hp motor will be larger, need bigger motor mounts, and will need larger electrical feed and larger breaker

check the rotation speed. different speed would mean different rate of air flow.

Taken from the Square D Slide Rule:

1 HP Single Phase

Full Load Amps-16

Minimum copper wire- 12 gauge

Circuit Breaker- 30 Amps

One half horsepower single phase:

Full load amps- 8

Minimum copper wire- 14

Circuit breaker-15

The motor circuit is sized for one half horse power and if you install a one horse power then the wires will be too small and get hot and could start a fire. You are dancing with the Devil if you don't know what you're doing.

If it's the same RPM, voltage and frame size it will work just fine. But, it will use twice the energy to accomplish the same result. Go ahead and replace with a 1/2 HP motor. It'll save you money in the long run.

if it came with a smaller motor then replace it with the same size

It should not need to be upgraded. If the 1 HP motor has the same speed as the old one and will fit OK no harm will be done, but first check for any fault which may have caused the original motor to fail.

Your evaporative cooler's components are designed to operative with a 1/2 hp motor only. sorry.