Aprilaire Thermostat Troubleshooting Guide
Is your Aprilaire thermostat acting up? Is it displaying error codes or is it simply not working as you expect it to? This quick troubleshooting guide for different Aprilaire thermostats will help you figure out the problem with your unit and fix it right away.
Note that some errors or faults require some level of skill to sort out. Don’t work on parts of the thermostat you don’t understand or are unsure of. We will also add links to the service and user manuals to ramp up the knowledge you have concerning your Aprilaire thermostat.
How to Program Aprilaire Thermostat
Before programming your programmable Aprilaire thermostat, you first have to set the time since it needs the clock to implement the different timed settings you will program into it.
- The first step is pressing the program button. This allows you to adjust the time settings.
- Usually, the AM/PM flash and using the Up and down button select the appropriate one and then press mode.
- Proceed to the Hour which by now is flashing and also use the up and down button to adjust it. Save the change by pressing mode. Adjust the minutes using the same procedure and save the change as done earlier. The thermostat will indicate Done if no other button is touched.
Your thermostat will use the time settings to automatically adjust to the programming schedules of WAKE, LEAVE, RETURN and SLEEP.
Changing Program Schedules
- Press the program button twice for the device to enter the program setting mode.
- Use the up and down button to adjust the start time.
- Then press mode, the Heat setting will flash on the display screen (use the up and down button to adjust the temperature).
- When you press the mode again the COOL setting will flash (use the up and down button to make relevant adjustments).
The programming procedure is the same for the other program options like sleep, leave and return options, you simply repeat the earlier steps when you press the mode key.
Aprilaire 8244 Thermostat Troubleshooting Guide
| Problem | Cause | What to Do |
|---|---|---|
| No Heat/No Cool/No Fan (common problems) | 1. Blown fuse or tripped circuit breaker. 2. Furnace power switch to OFF. 3. Furnace blower compartment door or panel loose or not properly installed. | 1. Replace fuse or reset circuit breaker. 2. Turn switch to ON. 3. Replace door panel in proper position to engage safety interlock or door switch. |
| No Heat | 1. Pilot light not lit. 2. System Switch not set to HEAT. 3. Loose connection to thermostat or system. 4. Furnace Lock-Out Condition. Heat may also be intermittent. 5. Heating system requires service or thermostat requires replacement. | 1. Re-light pilot. 2. Set System Switch to HEAT and raise setpoint above room temperature. 3. Verify thermostat and system wires are securely attached. 4. 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. Set System Switch to HEAT and raise the setpoint above room temperature. A soft click sound should be heard on the thermostat after a few seconds. If the thermostat does not click on, contact your heating and cooling service person or place of purchase for a replacement. |
| No Cool | 1. System Switch not set to COOL. 2. Loose connection to thermostat or system. 3. Cooling system requires service or thermostat requires replacement. | 1. Set System Switch to COOL and lower setpoint below room temperature. 2. Verify thermostat and system wires are securely attached. 3. Same procedure as diagnostic for No Heat condition except set the thermostat to COOL and lower the setpoint below the room temperature. Wait for the click for up to 5 minutes. |
| Heat, Cool or Fan Runs Constantly | 1. Possible short in wiring. 2. Possible short in thermostat. 3. Possible short in heat/cool/fan system. 4. Fan Switch set to Fan On. | Check each wire connection to verify they are not shorted or touching together. No bare wire should stick out from under terminal screws. 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. |
| Furnace 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. | 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, go to menu mode 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 changing cycle time from FAST to SLOW on the menu mode, contact a local service person for additional suggestions. |
| Cooling Cycles Too Fast or Too Slow (narrow or wide temperature swing) | The location of the thermostat and/or the size of the Cooling System can influence the cycle rate. | The cycle rate for cooling is fixed and cannot be adjusted. Contact a local service person for suggestions. |
| Thermostat Setting and Thermostat Thermometer Disagree | Thermostat thermometer setting requires adjustment. | The thermometer can be adjusted +/- 4 degrees. t |
| Blank Display and/or Keypad Not Responding | 1. Thermostat loss of power. 2. Voltage spike or static discharge. | 1. Check possible blown fuse or tripped breaker. 2. Turn system power off. Wait for 5 minutes and turn the power on. |
Aprilaire Thermostat 8463 Troubleshooting
| Problem | Solution |
|---|---|
| DISPLAY IS BLANK | • Check circuit breaker and reset if necessary. • Make sure power switch at heating & cooling system is on. • Make sure furnace door is closed securely. • If thermostat is battery powered, make sure fresh AA alkaline batteries are correctly installed |
| TEMPERATURE SETTINGS DO NOT CHANGE | Make sure heating and cooling temperatures are set to acceptable ranges: • Heat: 45° to 90°F (7° to 32°C). • Cool: 50° to 99°F (10° to 37°C) |
| HEATING SYSTEM DOES NOT RESPOND ("HEATING” APPEARS ON SCREEN) | • Check for 24 VAC at the equipment on the secondary side of the transformer between power and common. If voltage is not present, check the heating equipment to find the cause of the problem. • Check for 24 VAC between the heat terminal (W) and the transformer common. If 24 VAC is present, the thermostat is functional. Check the heating equipment to find the cause of the problem. • Check for loose or broken wires between the thermostat and the heating equipment |
| COOLING SYSTEM DOES NOT RESPOND ("COOLING" APPEARS ON SCREEN) | • Check for 24 VAC at the equipment on the secondary side of the transformer between power and common. If voltage is not present, check the cooling equipment to find the cause of the problem. • Check for 24 VAC between the cooling terminal (Y) and the transformer common. If 24 VAC is present, the thermostat is functional. Check the cooling system to find the cause of the problem. • Check for loose or broken wires between the thermostat and the cooling equipment |
| FAN DOES NOT TURN ON IN A CALL FOR HEAT | • Check System Setting #02 (Fan Control), to make sure the fan control is properly set to match the type of system |
| HEAT PUMP ISSUES COOL AIR IN HEAT MODE, OR WARM AIR IN COOL MODE | • Check System Setting #12 (Reversing Valve), to make sure it is properly configured for your system |
| HEAT/COOL BOTH ON AT SAME TIME | • Check SW1 (Equipment Type), to make sure it is set to match the installed heating/cooling equipment • Check to make sure heating and cooling wires are not shorted together |
| HEATING EQUIPMENT IS RUNNING IN COOL MODE | • Check SW1 (Equipment Type), to make sure it is set to match the installed heating/cooling equipment |
| "HEATING" IS NOT DISPLAYED | • Change the System Mode to Heat, and set the temperature level above the current room temperature |
| "COOLING" IS NOT DISPLAYED | • Change the System Mode to Cool, and set the temperature level below the current room temperature |
Other Aprilaire thermostats that take the above troubleshooting process include:
- Aprilaire 8336
- Aprilaire 8081TT
- Aprilaire 8355
- Aprilaire 8444
You can check out our Aprilaire thermostat manuals download page to get more detailed information about your thermostat. The user and installation manuals will have all the information you need to troubleshoot your thermostat better.