Changing Polarity of 12 Volt exhaust fan motor

Good afternoon all,

I have had to replace the exhaust fan impeller in our van. The motor runs anti clockwise & the blades were set on the old impeller in such a way that it did exhaust air from the toot.

All impeller's at our local Jayco spare parts have the blades set in such a way (opposite pitch) that with the motor running anti clockwise they draws fresh air in.

The bloke in the spare parts section reckons all I need do is reverse the polarity on the motor to make it run the opposite way & all will be unky dory.

However I don't want to damage the motor & would like some sort of confirmation that it is OK to simply swap the two wires over going to the motor & that this will change motor direction.

Thanks