Toptech thermostat troubleshooting

SymptomPossible CauseCorrective 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 Heat1. Pilot light not lit.Re-light pilot.
2. System Switch not set to HEAT.Set System Switch to HEAT and raise setpoint 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 thermo- stat is operating properly If the thermostat does not dick, try the reset operation listed above. If the thermostat does not dick after being reset contad your heating and cooling service person or place of purchase for a replacement. If the thermostat dicks, contad the furnace manufacturer or a service person to verify the heating is operating correctly.
No Cool1. System Switch not set to COOL.Set System Switch to COOL and lower setpoint 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 connedion 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 manufadurer of your system or service person can instrud you on how to test the Heat/Cool system for corred operation. If the system operates corredly. replace the thermostat.
2. Possible short in thermostat.
3. Possible short in heat/cool/fan system.
4. Fan Switch set to Fan On.
Furnace (Air Conditioning) Cycles Too Fast or Too Slow (narrow or wide temperature swing)1. The location of the thermostat and/or the size of the Heating (Cooling) System may be influencing the cycle rate.Digital thermostats normally provide predse temperature control and may cyde faster than some older mechanical models. A faster cyde 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, dip Jumper W-905 as mentioned in the instrudions for Hydronic Heating Systems. It is not possible to shorten the cyde time. If an acceptable cyde rate is not achieved as received or by clipping W-905 contad a local service person for additional suggestions.
Thermostat Setting and Thermostat Thermometer Disagree1. Thermostat thermometer setting requires adjustment.The thermometer can be adjusted +/- 3 degrees. See Temperature Display Adjustment in the Operation sedion.
Blank Display and/or Keypad Not Responding1. Voltage spike or static discharge.Use the Reset Operation listed above.

Toptech R251W thermostat troubleshooting

Symptom:Potential Solution:
The word HEAT or COOL is flashing in the thermostat displayThis indicates that the heating or cooling system is currently running. When these systems are not running, HEAT or COOL will not flash
HEAT or COOL is flashing but the system is not runningThe thermostat is telling the heating or cooling system to run, but the system is not responding. You may need to call your local heating and air conditioning contractor
Thermostat does not turn on heating or cooling systemCheck to see if OFF is shown in display. This indicates that the system is turned off at the thermostat. Move the system selector switch to the HEAT or COOL position. After the compressor short cycle protection 5-minute period expires the system should start.
Compressor protection feature may be in effect due to compressor short cycle conditions. See section 6.
Heating or cooling system may be malfunctioning. Call a professional service technician immediately to verify system operation
Thermostat turns on heating instead of cooling or cooling instead of heatingCheck thermostat wiring to make sure that the heating and cooling stages are connected to the correct terminals on the wiring terminal block
Thermostat will not follow program set pointsCheck current time of day, day of week program settings. Make sure to verify AM/PM indicator is accurately displaying desired time settings. See section 4.
Check to see if OFF is shown in display. This indicates that the system is turned off at the thermostat. Move the system selector switch to the HEAT or COOL position. After the compressor short cycle protection period expires the system should start within several seconds.
Verify your program set point time entries. The heating and cooling programs utilize the same set point times, but have individual set point temperatures for the MORN, DAY, EVE and NIGHT set points. See section 4.
Thermostat program has been temporarily overridden and program indicator is flashing in the display. Press the HOLD button twice to return the thermostat to normal program operation or wait until next set point and the temporary override will expire.
Thermostat program is in Extended Hold (Vacation) Mode and HOLD is showing in display. Press HOLD button to release permanent hold and return the thermostat to normal program operation
Thermostat turns heating or cooling system on too often or not often enough: Increase or decrease first stage temperature differential setting as appropriate to provide the desired performance level
Low battery indicator is shown in thermostat displayReplace batteries immediately to maintain proper system operation
OFF is shown in thermostat display and heating or cooling system will not startThis indicates that the system is turned off at the thermostat. The thermostat must be in HEAT or COOL modes of operation to control the heating or cooling system. Move the system selector switch to the HEAT or COOL position
HI is shown in the thermostat display where the room temperature is normally displayedThe temperature sensed by the thermostat is higher than the 99˚ F (37˚ C) upper limit of the thermostat’s display range. The display will return to normal after the sensed temperature lowers within the 40˚ to 99˚ F (5˚ to 37˚ C) display range. Turn on the cooling system or use other methods to lower the temperature accordingly. This condition could occur from the system being turned off during an exceptionally warm period or upon installation when the thermostat has been stored for a long period of time in a warm vehicle or location prior to being installed
LO is shown in the thermostat display where the room temperature is normally displayedThe temperature sensed by the thermostat is lower than the 40˚ F (5˚ C) lower limit of the thermostat’s display range. The display will return to normal after the sensed temperature rises within the 40˚ to 99˚ F (5˚ to 37˚ C) display range. Turn on the heating system to raise the temperature as needed for comfort within the room. This condition could occur from the system being turned off during a cold weather period or upon installation when the thermostat has been stored for a long period of time in a cold vehicle or location prior to being installed. The thermostat should be allowed to warm up prior to installation to allow proper heating control once installed
Cannot program a set point temperature higher than 90˚ F (32˚ C)This is above the normal thermostat temperature setting range of 45˚ to 90˚ F (7˚ to 32˚ C)
Cannot program a set point temperature lower than 45˚ F (7˚ C).This is below the normal thermostat temperature setting range of 45˚ to 90˚ F (7˚ to 32˚ C)
Fan continues to run all the time whether the system is on or offCheck that the fan control switch is in the AUTO position. This will allow the fan to run only when the heating or cooling system is turned on and running. Check thermostat wiring to make sure that the fan control wiring is connected to the correct terminals on the wiring terminal block
The room is too warm or too coldVerify the current set point and make any changes that are necessary
System turns on prior to the end of a setback periodThermostat is in Adaptive Recovery Mode
NO AUX SET is shown in the thermostat display (model TT-P-421 only).The thermostat (model TT-P-421 only) is configured for a conventional system, and the system switch is in the EM HEAT position. The unit will still function in a conventional 2 stage HEAT mode, but the display will flash NO AUX SET. Move the system switch to the HEAT position