landlord was responsible for HVAC repairs. Now most of them place the cost on the tenant. In addition most commercial leases will have a clause that says you have to contract with an HVAC maintenance company to do quarterly maintenance on the HVAC system.

You deal with the issue by having the HVAC system inspected before signing the lease, and if it's old and likely to need repairs, then you negotiate for the landlord to make the repairs prior to the lease beginning.