Always follow the manufacturer's instructions and local codes. Lock out and tag out before service.

Commercial Rooftop Unit (RTU) Maintenance Checklist

Packaged gas heat / DX cooling preventive maintenance

Site / Facility:

Unit Tag / ID:

Make / Model:

Serial Number:

Date:

Technician:

Visit Type:Quarterly inspectionSpring start-up (cooling focus)Fall start-up (heating focus)

1Safety and Lockout

Inspect external unit electrical disconnect switch, weatherproof enclosure, and conduit fittingsApply lockout / tagout (LOTO) on all electrical power sources prior to opening high-voltage compartmentsVerify blower door safety interlock switch disconnects control circuit when access panel is removedInspect manual gas cock shutoff handle, gas train unions, and test with detector or bubble solutionSurvey roof access route, walking pads, parapet clearances, and verify fall protection tie-off points

2Filters and Airflow

Inspect air filters; replace dirty filters or wash reusable filter media

Filter specifications:Size:Qty:Type:Replaced today

Inspect filter track, holding racks, blank-off angles, and perimeter gaskets to eliminate dirty air bypassInspect supply blower wheel and housing; clean blade surfaces and verify dynamic balanceInspect flexible supply and return duct transitions for tears, air leakage, and detachment

Airflow & Static Pressure Measurements

Return static:in. w.g.

Supply static:in. w.g.

Total external static (ESP):in. w.g.

Nameplate max ESP:in. w.g.

3Belts, Motors and Bearings

Inspect V-belts for wear, surface cracks, glazing, rollover, and proper operating tension

Belt part / size:Condition:GoodAdjusted tensionNew belt installed

Check motor sheave and blower pulley alignment with a straight edge; check groove wear and taper-lock hubsCheck fan shaft bearings and blower motor bearings for play, rumble, or overheating; lubricate serviceable bearings per manufacturerInspect motor mounting base, adjustment bolts, and rubber vibration isolation grommetsInspect condenser fan blades for stress cracks, balance, tight hub setscrews, and motor shaft axial play

4Electrical

Incoming Supply Voltage (Under Load)

L1 - L2:V

L2 - L3:V

L1 - L3:V

Rated Voltage:V

Phase Voltage Unbalance:% (≤ 2% max)

Control Transformer Secondary:VAC (per manufacturer)

Motor Amp Draw vs. Nameplate RLA / FLA

Motor / Component	Nameplate Rating	Actual Running Amps (L1 / L2 / L3)
Supply Blower Motor	FLA	L1: A L2: A L3: A
Compressor 1	RLA	L1: A L2: A L3: A
Compressor 2 (if equipped)	RLA	L1: A L2: A L3: A
Condenser Fan Motor 1	FLA	Actual: A
Condenser Fan Motor 2	FLA	Actual: A
Combustion Draft Inducer Motor	FLA	Actual: A

Inspect contactors for contact pitting, silver erosion, charring, and verify free coil pull-in without buzzingCheck and torque all screw terminals, lugs, and spade connectors on contactors, boards, and terminal stripsInspect fuses, fuse clips for spring tension, and circuit breaker sizing against unit nameplate MOCP / MCAInspect wiring harnesses and low-voltage bundles for vibration rubbing, heat discoloration, and rodent chewing

Run / Start Capacitors tested:Measured:µFRated:µF (within the rating printed on the capacitor)

5Refrigeration Circuit

Refrigerant Operating Pressures & Temperatures

Circuit	Refrigerant	Suction Line	Superheat	Liquid Line	Subcooling
Circuit 1		psig Sat: °F Line: °F	°F Target: °F	psig Sat: °F Line: °F	°F Target: °F
Circuit 2		psig Sat: °F Line: °F	°F Target: °F	psig Sat: °F Line: °F	°F Target: °F

Need to work out actual superheat and subcooling from these readings? Use our Superheat & Subcooling Calculator.

Inspect liquid line sight glasses: verify solid liquid column (no bubbles) and dry indicator core (green/dry)Check compressor crankcase heaters: verify continuous power and warm compressor sump during standbyInspect copper suction and liquid lines for rubbing, oil spots, cracked schrader caps, and missing valve stemsInspect TXV thermal bulb contact, clamp tightness, clean copper pipe contact, and insulation wrap integrityVerify safety switches: high-pressure cut-out, loss-of-charge switch, and freezestat operating condition

A2L Units (R-454B / R-32), If Equipped

Confirm the refrigerant detection sensor is present and physically undamaged, with no fault or end-of-life/expiry indication showingTest the mitigation response (blower or ventilation activation) per the manufacturer's procedure and confirm it operates as designed

6Coils and Condensate

Inspect outdoor condenser coils: wash with low-pressure water if fouled; straighten bent aluminum finsInspect indoor evaporator coil face: inspect for biological growth, dirt buildup, corrosion, and frost patternsInspect condensate drain pan: verify positive slope toward drain, no rust-through, and absence of standing waterClear and prime condensate P-trap and drain line: verify free drainage to roof drain or drain terminationTest secondary condensate overflow float switch: confirm compressor and cooling circuit lock out on high water

7Economizer and Dampers

Inspect outdoor air (OA) and return air (RA) damper blades, side seals, and polyurethane blade edge gasketsCheck damper drive linkage, ball joints, and crank arms; confirm free movement through full stroke without bindingTest actuator motor spring-return stroke: confirm damper fully drives closed on power interruptionInspect outside air intake hood: clean mesh bird/insect screen and confirm barometric exhaust damper flaps freelyInspect and clean mixed air temperature sensor and outdoor enthalpy / dry-bulb changeover control sensor

Minimum ventilation position setpoint:% openCalculated fresh air:CFM

8Gas Heat

Inspect heat exchanger tubes and vest plate: check for hairline cracks, rust perforations, weld separation, and sootInspect combustion draft inducer blower motor, scroll housing, cooling wheel, and flue exhaust terminationInspect draft proving pressure switch and silicone tubes: verify clear ports and proper cut-in / cut-out differentialClean flame sensor rod with fine abrasive pad; inspect spark electrode / hot surface igniter for cracksInspect burner orifices, primary air shutters, and burner ribbon ports for rust, insect nests, and correct alignmentObserve burner ignition and main flame: steady blue cone, tight flame retention, no rollout, lifting, or yellow tipping

Gas Combustion & Temperature Rise Readings

Gas Manifold Pressure:in. w.g.(Rated: in. w.g.)

Flue Gas CO:ppm(Record air-free CO; compare to the manufacturer's limit)

Supply Air Temp:°F

Return Air Temp:°F

Measured Temp Rise:°F(Nameplate: – °F)

Test primary high-temperature limit switch, auxiliary limit switches, and flame rollout safety thermal cutouts

9Controls, Thermostat and Sequence Check

Verify space thermostat or building automation system (BAS) temperature sensor calibration and schedulesConfirm cooling sequence: Stage 1 Y1 call, Stage 2 Y2 call, economizer lockout, compressor anti-cycle timerConfirm heating sequence: W1 heat call, draft pre-purge, ignition trial, flame rectification, indoor blower delayVerify indoor blower continuous fan mode (“FAN ON”) and automatic cycle mode (“FAN AUTO”)Confirm economizer integrated cooling changeover: modulates dampers on mild days, enables compressor on hot days

Control board error code history:Fault codes cleared after test

10Roof Curb and Cabinet

Inspect roof curb flashing, pitch pans, membrane counterflashing, and sealant beds for weather integrityInspect exterior cabinet panels, access door perimeter seals, and corner posts for air leaks and water entryVerify all panel latches, quarter-turn fasteners, and sheet metal screws are tight; replace missing fastenersInspect gas pipe, electrical power conduit, control wiring, and condensate penetrations through roof curb deckInspect cabinet interior thermal and acoustic insulation for delamination, loose edges, or airflow erosion

11Notes and Sign-Off

Deficiencies Identified & Corrective Actions Completed:

Parts Replaced / Materials Used:

Overall Unit Operating Status:

Pass — Fully OperationalConditional — Repairs RecommendedOut of Service — Tagged Out

Technician (Print):

Technician Signature:

Sign-off Date:

Customer / Facility Rep:

Customer Signature:

Sign-off Date: