Troubleshooting A Faulty Thermostat

Faulty and defective thermostat could be one of the causes of a malfunctioning HVAC. Do not panic if you feel that the thermostat has gone awry. The problem could be a minor one and can be troubleshot at home itself. Here are top problems that are caused by a faulty thermostat. Let’s see how to troubleshoot them-

HVAC is not heating

This can be caused by multiple reasons. But if the problem is because of the thermostat, then check if it is heat mode. The temperature set in the unit should be a few degrees above the room temperature. When you crank up the thermostat, you will hear a click. The heating system will respond to this click by commencing its operation. Wait for some time to allow it begin heating.

If connections to the thermostat have become loose, then heating unit will not respond to it. You will require checking if the thermostat and system wires are securely attached. Also check if the batteries have run out. In case none of these work out, you will require placing call with a HVAC technician.

Note: The same phenomenon can be observed in cooling mode as well.

Furnace is locked out

Sometimes the furnace is locked out and therefore will not respond to the thermostats. There are several safety sensors that check on furnace operation. In case any of the sensors detect an abnormal functioning of the furnace it will send signal to the furnace controller ASAP. The controller will prevent fuel to flow into the furnace and thereby shut it down to prevent a mishap or damage to the unit. This condition is known as lock out. Your furnace normally will remain in the locked-out state until you manually reset it. Reset it and then set the thermostat of the furnace to resolve the problem.

The fan is running continuously

This can be caused by a variety of causes. But if the problem stems from the thermostat, then check if the fan is set in Auto mode. In this setting, the fan will run only when the machine heats and cools. But if it set in Fan mode, then it continuously runs.

The setting of the thermostat disagrees with its thermometer

You have to adjust the thermostat in this case. If your thermostat has a mercury unit inside it you can adjust the temperature indicator with a small screwdriver. In case of a digital thermostat, the thermometer can be adjusted ±5 degrees.

The furnace is cycling on and off too frequently

Again this problem can be caused by various reasons. It can be caused by inappropriate location of the thermostat. If it is placed closed to an area which gets exposed to lot of sunlight or outside air, it affects the temperature the thermostat "sees." So position it where it will not be exposed to heat of the sunlight or other electrical appliances. Ensure that it is not blocked by any furniture or curtain. Also note that digital thermostat controls the temperature precisely therefore cycles faster than older mechanical models. Check the manufacturer's manual to adjust the cycle time faster or slower.

How to test a thermostat-

Here are some steps to test a thermostat

• Check if the thermostat is set in heating or cooling mode. In heating mode it should be a few degrees higher than room temperature. In cooling mode it should be a few degrees lower.

• To check the connections to thermostat from heating device turn on the power from the breaker. Now remove the cover to the thermostat. It will come off with gentle prying by hand.

• Now check the wires that connect to various terminals on the wall plate of the thermostat. Ensure that each wire is attached firmly to its respective mounting screw. If a wire has turned loose feed it through the terminal and retighten the screw,

• Now flip the breaker to see if the thermostat is working. If it does not, remove the cover again. Choose the red and white wires, if the furnace is having a problem in kicking on, or the red and green wires if there is an issue with the A/c comic on. Unscrew any of the pairs according to your need and wrap them together. Now turn on the breaker. If the blower comes on -- for furnaces or air conditioning systems -- the thermostat is bad.

Disclaimer: Although these are the typical methods used to troubleshoot a thermostat they can vary from place. Please consult the professional service provider as the details are for information purposes.



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