Check all the hoses going to and from the unit (they should be free of wear and tear)
If you still have a problem, then it’s time to check the thermostat. First, let’s discuss the problem of no heat. There are some possible causes such as blown fuse or tripped circuit breaker. If you’re changed the fuse or reset the breaker and still have no heat then the problem then it could be:
- Loose wires
- Dirty thermostat
- Bad battery (a problem only for digital electronic thermostats)
Solving this problem requires a: small, soft paintbrush and screwdriver.
- Use the screwdriver to remove the cover
- Use the paintbrush to clean the components such as the small metal plates and wires. Be careful. Do not touch any of the thermostat’s interior parts with your fingers.
- Turn the thermostat to the lowest setting and gently clean the bimetallic coil (with paintbrush).
- Turn the thermostat to the highest setting and gently clean the bimetallic coil
- Return the thermostat to its normal setting
- Move the anticipator (the small metal tab right in from the arcing printed scale) in both directions
- Check for any loose or disconnected wires and tighten them
- Use the screwdriver to reinstall the cover
- Turn the furnace on
HVAC thermostat repairs also can also occur when the heat doesn’t exceed or even reach the temperature setting. There’s no cleaning involved because the heat anticipator may not be set correctly or your thermostat was placed on the wall without being leveled. Use a level to make sure the thermostat is mounted correctly on the wall. If it isn’t:
- Remove the thermostat cover
- Loosen the screws holding it to the wall
- Level the thermostat
- Tighten screws
- Replace thermostat cover
If the thermostat is leveled, it may be the heat anticipator. After you remove the cover, move the anticipator (the small metal tab right in from the arcing printed scale) in both directions. This should adjust the anticipator.
You may notice that I mentioned four common HVAC thermostat repairs. So far we’ve covered:
- No heat coming from the furnace
- Heat doesn’t reach the temperature setting
- Heat doesn’t exceed temperature setting
If none of these HVAC thermostat repairs work, let me know. Your HVAC system may have a more serious thermostat problem such as faulty wiring. Often times I make these types of simple HVAC thermostat repairs during an annual maintenance so your HVAC system is ready for whatever Lubbock weather decides to give us.