Brand: LENNOX
Category: HVAC
Manual Type:
Language:
Manual for ZGC SERIES - Troubleshooting and error codes + PDF Download
Uploaded: March 30, 2025, 4:25 p.m.
Manual Publish Date: 2018-01-01
Warranty Summary
No warranty information provided in this manual.
Cooling Operation:
The cooling system operates in stages based on thermostat demand. First stage cooling engages compressor 1, and increased demand activates compressor 2. The blower operates at different speeds (low, medium, high) controlled by a VFD based on cooling demand.
Heating Operation:
Heating is also staged. First stage heat activates the combustion air inducer and then the gas valve at low fire. Second stage heat increases the gas valve to high fire. The burner control system manages ignition, flame sensing, and safety limits.
Blower Operation:
The blower speed is controlled by a Variable Frequency Drive (VFD) and operates at different speeds depending on cooling or heating demand. It can also be set to run continuously via thermostat settings.
Troubleshooting and error codes
| LED Flashes | Indicates |
|---|---|
| Slow | Normal operation. No call for heat. |
| Fast | Normal operation. Call for heat. |
| Steady Off | Internal control fault OR no power to control OR Gas Valve Relay Fault. |
| Steady On | Control internal failure. |
| 2 | Lockout. Failed to detect or sustain flame. |
| 3 | Prove switch open or closed or rollout switch open. |
| 4 | Limit switch is open and/or limit has opened three times. |
| 5 | Flame sensed but gas valve solenoid not energized. |
Troubleshooting and error codes
| LED Flashes | Indicates |
|---|---|
| Slow | Normal operation. No call for heat. |
| Fast | Normal operation. Call for heat. |
| Steady Off | Internal control fault OR no power to control OR Gas Valve Relay Fault. |
| Steady On | Control internal failure. |
| 2 | Lockout. Failed to detect or sustain flame. |
| 3 | Prove switch open or closed or rollout switch open. |
| 4 | Limit switch is open and/or limit has opened three times. |
| 5 | Flame sensed but gas valve solenoid not energized. |