A thermostat is simply a switch: inside it is a mechanism that activates whenever it detects a temperature that is too high or too low. And since it’s a switch, you can turn it off.
First, make sure the thermostat is on and in A/C or Heat. See if there are any schedule overrides. Finally, replace your batteries if your unit is battery powered.
Not at “room temperature” yet? Now it’s time to check the HVAC unit itself without going through the thermostat.
Supplies needed: masking tape and a pen or pencil, flat head screwdriver, Phillips head screwdriver
How to bypass the thermostat
1. Turn off the circuit breaker for your HVAC system.
2. Remove the thermostat cover plate with a flathead screwdriver. (Each model is different: some will have an easily removable cover plate, while others require you to twist, push down on a tab, or remove a few screws.)
3. Use a Phillips head screwdriver to remove the wall mounting screws from the thermostat.
4. Using masking tape, label the wires coming out of the thermostat. They correspond to the letters R, W, Y, G and C on the thermostat terminals.
5. Carefully unscrew the thermostat terminals, then disconnect the wires from your thermostat. You can use some duct tape to secure the wires to prevent them from falling back into the hole in the wall.
6. Connect the R and W wires. The other wires must not be in contact with each other. Turn on the circuit breaker for the HVAC unit; the oven should turn on. Turn off the circuit breaker and untwist the R and W wires.
7. Using the R and G wires, repeat step 6. This should cause the fan to turn on. Turn off the breaker to the HVAC unit and untwist the wires.
8. If steps 6 and 7 caused the oven and fan to come on, then you have a bad thermostat. Replace your unit as soon as possible.
9. However, if the tests did not turn on the heat or fan, the HVAC system may be at fault. Make sure your unit is receiving power; if it’s getting power but not working, this could indicate a break in the wire connecting the thermostat to the oven or a problem with the actual oven. At this point, you’ll want to call in a professional for an evaluation.
Whatever the results, you’ve just saved a piece of the change by doing these tests yourself.