When we rent room or house, maintenance IE leaking aircond is paid by Tenant or Landlord?

u la cos u use and spoil it.

It depends on the terms in the tenancy.
But usual 'fair basis' is landlord service the air-cond before start of tenancy.
Tenant undertake to maintain/service air-cond on intervals of 3-6 months once.

if roof leaking then owner lo, cos not u use one.

No, its just an old aircond. Been using it for a year, so it leaked.