What is wrong? › Commercial HVAC
A jump in the power bill is the unit telling you something
The Department of Energy puts the saving from a clean filter alone at 5 to 15 percent, and DOE's maintenance research finds preventive maintenance saves 12 to 18 percent on average against run-to-failure.
What is probably happening
- Dirty filters and coils making the unit run longer for the same cooling.
- An economizer stuck open, cooling outside air all summer.
- A refrigerant leak: the unit runs constantly and never quite gets there.
- Electric heat strips running in cooling season on a heat pump unit, or a schedule that runs the unit all night with nobody in.
- Or the rate went up. Check kWh on the bill, not just dollars.
Do this in the next five minutes
- Compare kWh this month to the same month last year. If kWh is flat, it is the rate, not the unit.
- Check the thermostat schedule. Set unoccupied hours to set back, not off.
- Change reachable filters and note the date.
- Walk the roof line from the ground: is the unit running at 7 am before anyone is in?
- Book a maintenance visit and ask for an economizer check and coil cleaning.
Do not
- Do not shut the outside air damper to save money. You trade a small saving for air quality complaints.
- Do not buy a new unit on the promise of savings alone without seeing the old unit's actual condition and runtime.
- Do not set the thermostat to Off overnight in a humid climate. The building soaks up moisture and the unit works harder in the morning.
Who to call
A licensed commercial HVAC contractor
Coil cleaning, economizer repair, leak search and control scheduling are all maintenance on the unit you already have.
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What it should cost
$300 to $600 basic, $800 to $1,500 full coverage, per rooftop unit per year
Maintenance plan pricing for a 5 to 15 ton rooftop unit, industry vendor (Oxmaint, February 2026), not neutral research
Source: Oxmaint, HVAC maintenance plan pricing calculator, February 2026 (vendor). View source
National published range, not a quote for your job. The full cost table for this trade is on the commercial hvac page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- Can you check the economizer, the refrigerant charge and the coils on one visit, and note each on the report?
- Is the unit running outside occupied hours, and can you fix the schedule while you are here?
- Is any electric heat energising during cooling?
- What is the unit's age and condition, honestly, and what would you expect it to cost to keep for three more years?
End the call if
- A replacement pitch built only on 'new units are more efficient' with no diagnosis of why the bill rose.
- A refrigerant top up with no leak search.