One time rent discount for heat issues

[Shawn H.]

We recently had a heat pump replaced in one of our units. The new unit should be more efficient. The first full bill after install was $100 higher than the previous month. I can check the usage online through the electric company, so I suspected something was wrong. When I went to look at the unit, the thermostat was set on 68, so it was set reasonably. The tenant was unaware of a high bill at this point. Part of the increase is due to colder weather, maybe $40-$50. I called the installer to look at the unit. 2 problems: low refrigerant and the breaker to the outside unit was off, not tripped, off. The installer of course says breakers were on when they were finished. The tenant is a single mom, good tenant, I really don't think she flipped the breaker. I believe everything is now working correctly. The tenant mentioned the higher bill, but didn't ask for any discount. Should I give her a one time discount? I don't feel like it is my fault, I have been proactive on having a unit installed and checking proper operation, but I want to keep her happy. The installer is claiming no fault. I don't mind giving a credit, but I don't want to get into the trap of her thinking a discount will be due anytime a bill is high. What do you think?