How to make sure your tenant will Change an Air Conditioner Filter?

[A W]

I think even if I put in the lease, it is hard to monitor/enforce that.. How frequently do you require them to change the filter? every 3 month or every 1 month?

Thanks.

[Ralph S.]

Pride of Ownership is only found in, uh, owners.
You really can't delegate those kind of things to tenants and trust they'll get done.
And, having shelled out $$$ to replace induction motors in furnances on several occasions, I can attest to the need.
Landlording is not just turning over a unit to a tenant and hoping for the best cause it's in the lease, or trying to minimize visits to your units. These can be a recipe for disaster (been there, too). Any routine maintenance and inspection is best done by the landlord, whether it is furnace filters, smoke detector batteries, checking for leaks under the sinks or anything else. It's the only way to insure these things get done is with routine inspection. It will also keep the tenant on thier toes, knowing the LL will be poking under sinks and going through all the rooms.
It's your property, not theirs. If you don't wanna, how can you expect them to?