Aprilaire thermostat troubleshooting

Aprilaire 8263 thermostat troubleshooting

SymptomPossible CauseCorrective Action
No Heat/No Cool/No Fan (common problems)1. Blown fuse or tripped circuit breaker.1. Replace fuse or reset breaker.
2. Furnace power switch to OFF.2. Turn switch to ON.
3. Furnace blower compartment door or panel loose or not properly installed.3. Replace door panel in proper position to engage safety interlock or door switch.
No Heat1. Pilot light not lit.1. Re-light pilot.
2. System Switch not set to HEAT.2. Set System Switch to HEAT and raise setpoint above room temperature.
3. Loose connection to thermostat or system.3. Verify thermostat and system wires are securely attached.
4. Furnace Lock-Out Condition. Heat may also be intermittent.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.
5. Heating system requires service or thermostat requires replacement.5. 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 Cool1. System Switch not set to COOL.1. Set System Switch to COOL and lower setpoint below room temperature.
2. Loose connection to thermostat or system.2. Verify thermostat and system wires are securely attached.
3. Cooling system requires service or thermostat requires replacement.3. 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 Constantly1. Possible short in wiring.1.-4. 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 on page 7. 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)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, change the cycle rate to "SL“ in the configuration menu. It is not possible to shorten the cycle time. If an acceptable cycle rate is not achieved as received or by changing the cycle rate, 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 DisagreeThermostat thermometer setting requires adjustment.The thermometer can be adjusted +/- 4 degrees. See Select Temperature Display Adjustment (#5 in the Configuration Menu section).
Thermostat Does Not Follow Program1. AM or PM set incorrectly in program.1.-3. Check current clock and program settings including the AM or PM designations for each time period. If a voltage spike or a static discharge occurs use the Reset Operation listed on page 7 in this Troubleshooting section.
2. AM or PM set incorrectly on the clock.
3. Voltage spike or static discharge.
4. Thermostat may be performing Progressive Recovery actions.4. Disable Progressive Recovery from the Configuration Menu if this feature is not desired.
Blank Display and/or Keypad Not RespondingVoltage spike or static discharge.If a voltage spike occurs, use the Reset Operation listed on page 7 in this Troubleshooting section.
Clock Loses or Gains TimeLoss of power to thermostat.The thermostat will maintain its program in memory even with no power but the clock time will be incorrect when power is restored.
See No Heat/No Cool/No Fan (common problems) in the Troubleshooting chart on page 7 for items to check in the system.
Heat or Cool Starts EarlyProgressive Recovery activated.See Configuration Menu item #4.

Aprilaire 8355 thermostat troubleshooting

SYMPTOMREMEDY
Thermostat does not turn on system.Check Wiring (see INSTALLATION).
Check fuse. Replace with 3 amp fuse if fuse has opened. Five minute compressor short cycle protection may be in effect. Press RESET to override. NOTE: This will erase programming.
Thermostat turns on and off too frequently.Increase Temperature Differential (see PROGRAMMING).
Display is blank, flashing or constant "LO BAT."Replace batteries.
Time shown on display is not the current time of day.Change time of day setting (see PROGRAMMING).
Thermostat does not follow program.Thermostat in MANUAL mode (see PROGRAMMING).
Thermostat may not have been programmed in HEAT or COOL position. Verify program.
Check AM/PM indicators at time of day and programmed time changes (see PROGRAMMING).
Verify program and day of week is correct (see PROGRAMMING).
Thermostat does not advance day of week.To view or change day of week use method on page 5.

Aprilaire 8620 thermostat troubleshooting

ProblemCause/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 CHANGEMake sure heating and cooling temperatures are set to acceptable ranges:
• Heat: 40° to 90°F (4° to32°C).
• Cool: 50° to 99°F|10° to37°C).

HEATING SYSTEM DOES NOT RESPOND ("HEATING” APPEARS ON SCREEN)• Check for 24VAC 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 24VAC between the heat terminal (W| and the transformer common. If 24VAC 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 24VAC 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 24VAC between the cooling terminal (Y) and the transformer common. If 24VAC 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 05 (Fan Control), to make sure the fan control is properly set to match the type of system (see page 8).
HEAT PUMP ISSUES COOL AIR IN HEAT MODE. OR WARM AIR IN COOL MODE• Check System Setting 31 (O/B Operation) to make sure the reversing valve operation matches the heat pump.
HEAT/COOL BOTH ON AT SAME TIME• Check SW1 (Equipment Type), to make sure it is set to match the installed heating/cooling equipment (see page 8).
• 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 (see page 8).
“HEATING” IS NOT DISPLAYED• Check Installer System Setting number 01 (Control Setup) is set correctly.
• Change the System Mode to Heat, and set the temperature level above the current room temperature.
“COOLING" IS NOT DISPLAYED• Check Installer System Setting number 01 (Control Setup) is set correctly.
• Change the System Mode to Cool, and set the temperature level below the current room temperature.
HUMIDIFIER DOES NOT OPERATE IN AUTO MODE• Check Installer System Setting number 11 (Outdoor Sensor) is set to yes.
• Verify that the outdoor sensor is functioning correctly. If the sensor is functioning correctly the outdoor temperature will display in the outdoor temperature location (see Home Screen on page 17 for the location).