Lennox Air Conditioner: Outdoor unit will not start – Lennox EL16KC1

Outdoor unit will not start - Lennox EL16KC1 on a Lennox air conditioner: Thermostat calls for cooling but the compressor and outdoor fan do not run.

Homeowner with a air conditioner problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Applies to: Lennox EL16KC1 (Elite) R-454B air conditioners, sizes -018 to -060

Common causes of outdoor unit will not start - lennox el16kc1

• No 24 VAC Y1 call or common
• High pressure switch open
• Low pressure switch open
• Timed-off control (A4) delay, if installed
• Refrigerant detection system (RDS) in leak mode
• Contactor or line voltage problem

How to fix outdoor unit will not start - lennox el16kc1: step by step

1. Check 24 VAC between Y1 (yellow) and C (black) at the outdoor unit wire connections.
2. If an A4 timed-off control is used, wait out its delay; Y1 goes to A4 terminal 2 and S4 to terminal 3.
3. Test high pressure switch S4: it should open at 590 +/- 10 psig and close again at 418 +/- 5 psig.
4. Check the low pressure switch S87 (opens at 40 +/- 5 psig, resets at 90 +/- 5 psig); a low charge will hold it open.
5. Check that contactor K1 pulls in and line voltage is within the nameplate range.
6. If the RDS board LED is flashing blue, the system is in leak mitigation and keeps the compressor off - find the leak or sensor issue first.
7. Crankcase heater should be powered 24 hours before start-up.

If the unit shows an error code, look it up: Lennox Air Conditioner codes

Models

EL16KC1-018-230AEL16KC1-024-230AEL16KC1-030-230AEL16KC1-036-230AEL16KC1-041-230AEL16KC1-042-230AEL16KC1-047-230AEL16KC1-048-230AEL16KC1-060-230A