Here you can find several troubleshooting instructions for the most popular thermostat models of Emerson brand. Each manual is presented in the form of a table for your convenience: it enlists the technical issue, the possible causes and ways to fix problems. Tables cover the whole range of failures and show how to perform troubleshooting manually or using WiFi programming. There’s also the error alert code table: it will help you to define the exact problem in a jiffy. If the following instructions are too challenging for you, please, contact the repair service provider.
| Problem | Cause | Solution |
|---|---|---|
| The maintenance wrench icon appears in the Energy Meter display. | There is a problem with the inputs to the Energy Meter. | |
| The display is blank after applying control power to the meter. | The meter is not receiving adequate power. | Verify that the meter control power is receiving the required voltage. Verify that the heart icon is blinking. Check the fuse. |
| The data displayed is inaccurate. | Incorrect setup values | Verify the values entered for Energy Meter setup parameters (CT and P I ratings, system type, etc.). |
| Incorrect voltage inputs | Check Energy Meter voltage input terminals to verify adequate voltage. | |
| Energy Meter is wired improperly. | Check all CTs and P i’s to verity correct connection to the same service, PT polarity, and adequate powering. | |
| Cannot communicate with Energy Meter from a remote personal computer. | Energy Meter address is incorrect. | Verify that the meter is correctly addressed. |
| Energy Meter baud rate is incorrect. | Verify that the baud rate of the meter matches that of all other devices on its communications link. | |
| Communications lines are improperly connected. | Verify the Energy Meter communications connections | |
| Verify the terminating resistors are properly installed on both ends of a chain of units. UniLs in the middle of a chain should not have a terminator. Verify the shield ground is connected between all units. |
| Comfort Alert Yellow Alert Codes | Cause |
|---|---|
| 1 Flash | Long run time |
| 2 Flashs | System pressure trip |
| 3 Flashs | Short cycling |
| 4 Flashs | Locked rotor |
| 5 Flashs | Open circuit |
| 6 Flashs | Open start circuit |
| 7 Flashs | Open run circuit |
| 8 Flashs | Welded Contactor |
| 9 Flashs | Low voltage |
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| No Heat/No Cool/No Fan (common problems) | 1. Blown fuse or tripped circuit breaker. | Replace fuse or reset breaker. |
| 2. Furnace power switch to OFF. | Turn switch to ON. | |
| 3. Furnace blower compartment door or panel loose or not properly installed. | Replace door panel in proper position to engage safety interlock or door switch. | |
| No Heat | 1. Pilot light not lit. | Re-light pilot. |
| 2. SYSTEM Switch not set to HEAT. | Set SYSTEM Switch to HEAT and raise setpoint temperature above room temperature. | |
| 3. Loose connection to thermostat or system. | Verify thermostat and system wires are securely attached. | |
| 4. Furnace Lock-Out Condition. Heat may also be intermittent. | Many furnaces have safety devices that shut down when a lock-out condition occurs. If the heat works intermittently contact the furnace manufacturer or local service person for assistance. | |
| 5. Heating system requires service or thermostat requires replacement. | Diagnostic: Set SYSTEM Switch to HEAT and raise the setpoint above room temperature. Within a few seconds the thermostat should make a soft click sound. This sound usually indicates the thermostat is operating properly. If the thermostat does not click, try the reset operation listed above. If the thermostat does not click after being reset contact your heating and cooling service person or place of purchase for a replacement. If the thermostat clicks, contact the furnace manufacturer or a service person to verify the heating is operating correctly. | |
| No Cool | 1. SYSTEM Switch not set to COOL. | Set SYSTEM Switch to COOL and lower setpoint temperature below room temperature. |
| 2. Loose connection to thermostat or system. | Verify thermostat and system wires are securely attached. | |
| 3. Cooling system requires service or thermostat requires replacement. | Same procedure as diagnostic for No Heat condition except set the thermostat to COOL and lower the setpoint below the room temperature. There may be up to a five minute delay before the thermostat clicks in Cooling. | |
| Heat, Cool or Fan Runs Constantly. | 1. Possible short in wiring. | Check each wire connection to verify they are not shorted or touching together. No bare wire should stick out from under terminal screws. Try resetting the thermostat as described above. If the condition persists the manufacturer of your system or service person can instruct you on how to test the Heat/Cool system for correct operation. If the system operates correctly, replace the thermostat. |
| 2. Possible short in thermostat. | ||
| 3. Possible short in heat/cool/fan system. | ||
| 4. FAN Switch set to Fan ON. | ||
| Furnace Cycles Too Fast or Too Slow (narrow or wide temperature swing) | 1. The location of the thermostat and/or the size of the Heating System may be influencing the cycle rate. | Digital thermostats normally provide precise temperature control and may cycle faster than some older mechanical models. A faster cycle rate means the unit turns on and off more frequently but runs for a shorter time so there is no increase in energy use. If you would like to increase the cycle time, clip Jumper W-905 as mentioned in the instructions for Hydronic Heating Systems. It is not possible to shorten the cycle time. If an acceptable cycle rate is not achieved as received or by clipping W-905 contact a local service person for additional suggestions. |
| Cooling Cycles Too Fast or Too Slow (narrow or wide temperature swing) | 1. The location of the thermostat and the size of the Cooling System can influence the cycle rate. | The cycle rate for cooling is fixed and can not be adjusted. Contact a local service person for suggestions. |
| Thermostat Setting and Thermostat Thermometer Disagree | 1. Thermostat thermometer setting requires adjustment. | The thermometer can be adjusted +/- 3 degrees. |
| Blank Display and/or Keypad Not Responding | 1. Voltage spike or static discharge. | Replace batteries and check heat/cool system for proper operation |
| 2. Battery change required. |
| Options | Default Setting | Additional Information |
|---|---|---|
| Does either a gas or oil furnace provide heating to your home? | GAS | Select GAS if you have either a gas or oil furnace. |
| (for either gas or oil furnace) | If you do not have agas or oil furnace select ELE. | |
| Do you have a Heat Pump? | OFF | If you do not have a Heat Pump select OFF. |
| (no Heat Pump) | If you have a Heat Pump, select (On1) for a 1 -stage, or (0n2) for a 2-stage Heat Pump | |
| Do you want the Cycle Rate to be Fast or Slow? | FA (fast) | Select SL (slow) if you have Hydronic (water or steam) Heating. |
| Otherwise, select default FA. | ||
| Do you want to activate Auto Changeover function? | OFF (no Auto Changeover) | Select default OFF for now. |
| How much displayed temperature offset do you want? | 0 (no offset) | Select default 0 for now. |
| Problem | Possible Cause | Corrective Action |
|---|---|---|
| Multi-stage Air Conditioner/Heat Pump Second, Third, and/or Fourth Stage Won’t Come On | Your thermostat is designed to determine the optimum time to activate the second stage. Simply raising the temperature in heating or lowering it in cooling will not always force the thermostat to bring the second stage on quickly. There is a time delay from 0-30 minutes depending on the performance of the first stage of the system. | Wait for the second, third, and/or fourth stage to come on. |
| No Cool | System switch not set to COOL. | Press SYSTEM button to select COOL and press © to lower the temperature setpoint below room temperature. |
| Outdoor unit disconnect or breaker tripped. | Verify the outdoor unit disconnect or breaker has not been tripped. | |
| Cooling system requires service or thermostat requires replacement. | To diagnose this condition: Press SYSTEM button to select COOL and press © to lower the temperature setpoint below room temperature. Within a few seconds the thermostat should make a soft click sound. This sound usually indicates the thermostat is operating properly. | |
| If the thermostat does not click after being reset, contact your installing contractor for a replacement thermostat. If the thermostat clicks, contact the furnace manufacturer or HVAC contractor for a service visit to verify the cooling is operating correctly. | ||
| No Heat | Pilot light not lit. | If it will not stay lit, call for service from your HVAC contractor. |
| System switch not set to HEAT. | Press the thermostat’s SYSTEM button one or more times to select HEAT and press to raise the temperature setpoint above room temperature. | |
| Furnace Lock-Out Condition. Heat may also be intermittent. | Many furnaces have safety devices that shut down when a lock-out condition occurs. If the heat works intermittently, contact the furnace manufacturer or your HVAC contractor for assistance. | |
| Heating system requires service or thermostat requires replacement. | To diagnose this condition: Press SYSTEM button to select HEAT and press © to raise the temperature setpoint above room temperature. Within a few seconds the thermostat should make a soft click sound. This sound usually indicates the thermostat is operating properly. If the thermostat does not click after being reset, contact Delmarva Power Energy Wise Rewards for a replacement thermostat. If the thermostat does click, contact the furnace manufacturer or your HVAC contractor for a service visit to verify the heating is operating correctly. | |
| Furnace (Air Conditioner) Cycles Too Fast or Too Slow (Narrow or Wide Temperature Swing) | The location of the thermostat and/or the size of the heating system may be influencing the cycle rate. | Electronic thermostats, like this one, normally provide precise temperature control and may cycle faster than some older mechanical models. A faster cycle rate means the unit turns on and off more frequently to maintain the desired temperature, but runs for a shorter time so there is no increase in |
| Thermostat Setting and Thermometer Disagree | Thermostat thermometer setting requires adjustment. | The thermometer can be adjusted +/– 5 degrees |
| Symptom | Possible Cause | Action |
|---|---|---|
| Display does not come on. | Thermostat is not being powered. | Check if the thermostat is mounted and latched on the wallplate—mount and latch the thermostat on the wallplate. |
| Check if the circuit breaker is tripped—reset the circuit breaker. | ||
| Check if the fuse is blown—replace the fuse. | ||
| Check if the system switch at the equipment is in the Off position—set to the On position. | ||
| Check wiring between thermostat and HVAC equipment— replace any broken wires. | ||
| If 24 Vac is present, proceed with troubleshooting. | ||
| Temperature setting does not change (Example: cannot set the heating higher or the cooling lower). | The upper or lower temperature limits were reached. | Check that the temperature setpoints are: Heating: 55 to 85°F (13 to 29°C) Cooling: 65 to 99°F (18 to 37°C). |
| Heating does not come on. | No power to the thermostat. System selection is not set to Heat. Heating setpoint is below room temperature. | Check that setpoint is above room temperature. |
| Check if the circuit breaker is tripped—reset the circuit breaker. | ||
| Check if the fuse is blown—replace the fuse. | ||
| Check if the system switch at the equipment is in the Off position—set to On position. | ||
| If 24 Vac is present, proceed with troubleshooting. | ||
| Wait five minutes for the system to respond (thermostat displays Wait). | ||
| Set system selection to Heat. | ||
| Cooling does not come on. | No power to the thermostat. System selection is not set to Cool. Cooling setpoint is above room temperature. | Check that setpoint is below room temperature. |
| Check if the circuit breaker is tripped—reset the circuit breaker. | ||
| Check if the fuse is blown—replace the fuse. | ||
| Check if the system switch at the equipment is in the Off position—set to On position. | ||
| If 24 Vac is present, proceed with troubleshooting. | ||
| Wait five minutes for the system to respond (thermostat displays Wait). | ||
| Set system selection to Cool. | ||
| System on indicator (flame=heat, snowflake= cool) is lit, but no warm or cool air is coming from the registers. | Heating/cooling equipment turns on the fan when the equipment has reached the setpoint. | Wait a minute after seeing the flame or snowflake and then check the registers. |
| System on indicator reads Filter and backlight is flashing. | Filter expired. | |
| Outdoor temperature not displayed or is incorrect. | Filter expired. | Press B twice for outdoor temperature when filter expiration shows on display. |
| Installer did not activate this option. Outdoor sensor is connected incorrectly. | ||
| Contact installer or service technician. | ||
| LED is lit. | System switch is set to Em. Heat. Compressor failure. | Move switch to Heat or Auto Contact service technician. |
| Message | Cause | Outputs |
|---|---|---|
| •P1” | Room probe failure | Compressor output acc. to par. “Con” and “COF” |
| “P2″ | Second probe failure | Outputs unchanged |
| “P3″ | Third probe failure | |
| “P4” | Fourth probe failure | |
| “HA’ | Maximum temperature alarm | |
| “LA” | Minimum temperature alarm | |
| “HA2” | Condenser high temperature | It depends on the “Ac2” parameter |
| “LA2” | Condenser low temperature | It depends on the “bLL” parameter |
| “dA” | Door open | Compressor and fans restarts |
| “EA” | External alarm | Output unchanqed. |
| “CA” | Serious external alarm (i1F=bAL) | All outputs OFF. |
| “CA” | Pressure switch alarm (i1F=PAL) | All outputs OFF |