Is there a law required by pa that landlord needs to replace the commercial hvac unit?

the answer to this question is probably in the terms of your lease.  I've seen responsbility for the HVAC unit in a commercial lease allocated to tenants or to landlords.  It just depends on the situation. If the unit services only your premises, if it's relatively small, if the lease is long enough to "recover" what you pay to replace it, usually that would mean the tenant picks it up. But if the landlord presented the lease to you and you didn't negotiate it, you are probably responsible for it. Read your lease -- that's the first step.  There is no commercial landlord law that speaks to this issue.