Tenant changing attic air filter

[Pete B.]

We have a home with an hvac unit in the attic, our lease requires tenants to replace the air filter. We had a tenant living here a couple years ago and replaced the hvac system while he was living here. We moved back in over a year after the new unit was installed, to find he never replaced the filter once, in over a year. The attic is accessed from the garage, and because of the installation of the piping to the unit, it is a little difficult to finagle the filter in and out. Should put in the lease that I replace the filter myself every 3 months for them, providing they leave clear accessibility to the attic? I dont want to shell out another 5k for a new hvac. Anybody change filters themselves?