NOT COOLING

AC Not Cooling — Outdoor Unit Running

NOT STARTING

Outdoor Unit Won't Start

FREEZING UP

Evaporator Coil Freezing — Ice on Refrigerant Lines

SHORT CYCLING

AC Turns On and Off Rapidly

CAPACITOR FAIL

Run/Start Capacitor Failure

CONTACTOR FAIL

Contactor Failure or Pitting

REFRIGERANT LEAK

Refrigerant Leak — Low System Charge

FAN MOTOR FAIL

Condenser Fan Motor Failure

LED OFF

No Power to Control Board

LED ON

Normal Operation — System Idle

1 FLASH

Normal — Heat Call Active

2 FLASH

System Lockout — Ignition Failed

3 FLASH

Pressure Switch Stuck Closed

4 FLASH

Pressure Switch Stuck Open

5 FLASH

Flame Sensed Without Gas Valve Command

6 FLASH

Power Reversed or No Ground

7 FLASH

Low Flame Signal

8 FLASH

Igniter Circuit Failure

10 FLASH

Rollout Switch Open

RAPID FLASH

Control Board Failure

NO HEAT

Furnace Not Producing Heat

SHORT CYCLE

Furnace Short Cycling

BLOWER CONTINUOUS

Blower Motor Runs Continuously

NOISY OPERATION

Unusual Furnace Noises

INDUCER NOISE

Inducer Motor Noise or Failure

LED OFF

No Power to Control Board

LED ON

Normal Operation — System Idle

1 FLASH

Normal — Heat Call Active

2 FLASH

System Lockout — Ignition Failed

3 FLASH

Pressure Switch Stuck Closed

4 FLASH

Pressure Switch Stuck Open

5 FLASH

Flame Sensed Without Gas Valve Command

6 FLASH

Power Reversed or No Ground

7 FLASH

Low Flame Signal

8 FLASH

Igniter Circuit Failure

9 FLASH

Grounding Problem — Flame Sense Affected

10 FLASH

Rollout Switch Open

11 FLASH

High-Stage Pressure Switch Open (Two-Stage Only)

RAPID FLASH

Control Board Failure / Communication Error

NO HEAT

Furnace Not Producing Heat

SHORT CYCLE

Furnace Short Cycling — Shuts Off Too Soon

BLOWER CONTINUOUS

Blower Motor Runs Continuously

NOISY OPERATION

Unusual Furnace Noises

INDUCER NOISE

Inducer Motor Noise or Failure

1 BLINK / 3 SEC

Normal Operation

2 FLASH

Thermopile Voltage Low

4 FLASH

Temperature Exceeded High Limit

5 FLASH

Temperature Sensor Failure

7 FLASH

Gas Control Valve Electronics Failure

8 FLASH

Insufficient Thermopile Power

NO HOT WATER

No Hot Water — Pilot Light Out

INSUFFICIENT HOT

Not Enough Hot Water — Runs Out Quickly

RUMBLING

Rumbling or Popping Noises During Heating

ELEMENT LED ON

Heating Elements Active — Normal

ELEMENT LED OFF

Elements Not Firing — No Demand or No Power

DISPLAY DASHES

Temperature Sensor Error

NO DISPLAY

No Power to Unit — Display Dark

LOW TEMP OUTPUT

Insufficient Temperature Rise — Unit Undersized

05

False Flame Detection

10

Abnormal Combustion — Blocked Vent

11

Ignition Failure — No Flame Detected

12

Flame Failure — Flame Lost During Operation

14

Thermal Fuse Activated — Overheat Safety

16

Overheating — Outgoing Water Too Hot

24

Abnormal Temperature Rise — Low Water Flow

29

Condensate Drain / Vent Blockage

32

Outgoing Water Temperature Sensor Failure

33

Incoming Water Temperature Sensor Failure

34

Combustion Air Temperature Sensor Failure

52

Gas Proportional Valve Failure

61

Combustion Fan / Blower Motor Failure

65

Water Flow Control / Flow Sensor Failure

72

Flame Detection Circuit Failure

99

Communication Error — Remote Controller

SCALE BUILDUP

Heat Exchanger Scale Accumulation

CONDENSATE ISSUES

Condensate Drain Problems

VENT ICE

Vent Termination Icing in Cold Climates

NO HOT WATER

No Hot Water — Complete Failure

INSUFFICIENT HOT

Runs Out of Hot Water Too Quickly

ECO TRIPPING

High-Limit Reset Button Keeps Tripping

LEAKING

Water Heater Leaking

ELEMENT SCALE

Heating Element Scale and Sediment Buildup

RUMBLING

Rumbling, Popping, or Banging Noises