Evaporator Coil Replacement
Step-by-step field checklist — recovery, removal, install, and startup
Indoor Evaporator Coil — Replace & Commission
Complete each step in order. Flag any item with an abnormal finding or that requires follow-up.
1. Pre-Work Verification
Confirm Coil Failure & Replacement Need
Verify evaporator coil is the correct diagnosis — confirm leak location, coil damage, or irreparable fouling
Verify Replacement Coil
Confirm replacement coil matches system — tonnage, metering device type (TXV or fixed orifice), refrigerant, and cabinet orientation (A, N, or slab coil)
New Filter Drier On-Hand
A new liquid line filter drier must be installed any time the refrigerant system is opened — confirm drier is correct size and type
Lock Out / Tag Out
Turn off thermostat, disconnect at air handler, and shut off outdoor unit breaker. Verify zero voltage at unit
2. Refrigerant Recovery
Recover Refrigerant from System
Connect recovery machine to service ports at the outdoor unit and recover all refrigerant into a certified recovery cylinder
Oil Acid Test
Test oil sample from system for acid contamination — determines if line set flush or additional driers are needed
3. Removal & Cabinet Access
Gain Access to Evaporator Coil
Remove air handler access panels, blower assembly if blocking access, and any duct connections to the coil cabinet
Disconnect Refrigerant Lines
Braze off or disconnect suction and liquid lines at coil connections. Cap open lines immediately to prevent moisture entry
Disconnect Condensate Drain Pan
Disconnect drain line from old coil drain pan. Inspect drain pan for cracks, mold, or damage — replace pan if needed
Remove Old Evaporator Coil
Slide or lift old coil assembly out of cabinet. Note orientation, metering device location, and any spacers or brackets for reinstall reference
Inspect Cabinet & Blower
With coil out, inspect inside of cabinet for mold, debris, or damage. Clean blower wheel if dirty. Replace blower capacitor if aged
4. Installation
Install New Filter Drier
Braze new filter drier into the liquid line before the coil metering device. Arrow pointing toward metering device. Flow nitrogen during braze
Set & Position New Evaporator Coil
Slide new coil into cabinet in correct orientation. Verify coil is fully seated, drain pan is aligned under coil, and metering device is accessible
Braze Refrigerant Line Connections
Braze suction and liquid line connections to new coil with nitrogen flowing. Inspect all joints for full silver braze penetration
Reconnect Condensate Drain
Reconnect drain line to new coil drain pan. Verify continuous slope to drain point — no sags, no standing water possible
Reassemble Air Handler
Reinstall blower assembly, reconnect supply plenum or duct, and resecure all access panels. Verify no air leaks at cabinet seams
5. Pressure Test, Evacuation & Recharge
Pressure Test with Nitrogen
Pressurize system to 150–200 psig with dry nitrogen. Leak check all new braze joints at coil and filter drier
Triple Evacuation
Evacuate to 300 microns or lower. Break with dry nitrogen, re-evacuate — repeat 3 times for thorough moisture removal
Recharge Refrigerant
Weigh in refrigerant to nameplate charge or verify by superheat/subcooling method. Document refrigerant type and amount
Condensate Drain Flow Test
Pour water into drain pan and confirm it drains freely with no backup. Test condensate pump if installed
System Start & Runtime Verification
Energize system and run in cooling mode. Verify pressures, amps, delta T, and no abnormal noise or frost on new coil
6. Documentation & Close-Out
Photo Documentation
Photograph old coil (leak location if visible), new coil installed, filter drier, braze joints, drain pan, and gauge readings at startup
Refrigerant Log
Document refrigerant type, amount recovered, amount recharged, and technician EPA certification number per Section 608 requirements
Warranty Registration
Register new coil warranty with manufacturer if required. Record coil model, serial number, and install date
Customer Walk-Through & Sign-Off
Explain what was replaced and why, filter maintenance reminder, and warranty terms. Obtain customer signature
Note: Always replace the filter drier when opening the refrigerant system. Never reuse an old filter drier — it cannot be reliably regenerated and will allow moisture and acid to circulate through the new coil.
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