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Before assuming the worst during an HVAC malfunction, take the time to thoroughly check all possible causes for the problem. The trouble could be caused by something as small, but as critical, as a nonfunctioning thermostat. Here are five ways to test your business thermostat to see it's preventing your heating and cooling system from working.

  1. Check the settings: Make sure the unit is turned on and receiving power. Check the function settings to ensure they are set to heating or cooling, as appropriate for the season. See if the temperature settings have been changed to something too high or low to let the system work. Look over the other settings and programming on your business thermostat to make sure there are no other changes that could affect HVAC system performance.
  2. Check the battery: Verify that the battery is working properly. Many modern thermostats get their power from a battery. Even if the display is lighted, the battery may still be too weak to control your furnace. If the battery has been in the thermostat for several months to a year, or even if you suspect the battery may be at fault, the best option is to put in a fresh one to be sure.
  3. Check the circuit breakers: Check breakers at the main circuit breaker panel for building, as well as any individual circuit breakers or safety controls that are in place on the HVAC units themselves. A tripped circuit breaker could shut off power to your heating and cooling system and prevent thermostat signals from reaching the HVAC equipment. If the furnace or air conditioner has power, and the thermostat itself is functional, then the problem may be in the wiring between the HVAC equipment and the thermostat.
  4. Check the signal: Make some changes in the settings at the thermostat to see if it is sending a signal to the HVAC unit. Have someone stand near the HVAC unit while you work the business thermostat. As temperature settings are raised or lowered, the thermostat should click or make an audible sound. At the same time, the air conditioner or furnace unit should also make a sound indicating that the signal has been received. Even if the HVAC unit doesn't switch on, it should still make that sound in response to the signal from the thermostat. If the unit doesn't make a corresponding sound, the problem is likely in the unit itself, the thermostat, or in the wiring between the HVAC unit and the thermostat.
  5. Conduct a switch bypass test: Turn off the power to the furnace and remove the thermostat from its mounting bracket on the wall to expose the wiring that comes through the wall from the furnace. Make careful note of the position and connections of the wires so they can be replaced later. Secure any wires in place so that they don't slip back through the hole in the wall. Remove the wires labeled R (or Rh) wire W. Connect these wires by twisting them together or using a wire connector. This will have the same effect of flipping the switch to turn the HVAC unit on. Restore power and see if the furnace or air conditioner comes on. If it does, the problem is most likely in the thermostat itself. If it doesn't, the problem may be in the HVAC unit, connecting wiring, or elsewhere in the system. Shut off the power again, return the wires to their original position, and replace the thermostat.

If these steps do not give you the results you need, contact your local trusted HVAC services provider for professional assistance.

Our goal is to help educate our customers about Plumbing, HVACR, Fire Protection and Alarm Systems in Mechanical, Commercial and Residential settings. For more information on testing your business thermostat, and to view projects we've worked on, visit our website!

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