Replacing a bad Evaporative cooler belt is part of regular maintenance and something that a home DIYer can do.
Each swamp cooler will have its own build and different belt sizes that can be bought at most home improvement stores, or online.
A bad swamp cooler belt will have cracks and pieces starting to break off from wear and tare.
Once it has cracks and breaks it will fail at any moment and stop blowing air into a home.
The first step is to be sure the unit is off and no power going to it.
Once the power is off the side panels need to be removed. The side panels usually simply push up and pull out.
Most evaporative coolers have a bracket the motor sits on which can be adjusted.
Locate the motor and the bracket it sits on.
Loosen the bolts. They will not need to be removed completely only loosened.
Loosen the bolts on the other side of the cage.
The bracket that holds the motor in place can be pushed up and the belt removed.
After the belt is removed if no size is visible on it take it with you to a hardware store and match it up to a new one.
Installing he new belt is simply the reverse of removing it.
The belt does not need to be extremely tight and can go in roughly 1/2 inch when pushed in on.
Replacing a swamp cooler belt is an easy task that most home do-it-yourself type of persons can do.
As always if in doubt call a professional to do it for you.
Keep in mind not all units are built the same, while there may be some differences the basics will be the same.
Often the hardest part especially on older units is getting the rusted bolts to loosen up.