Common Gas Furnace Issues to Check Before Calling
Check for electrical power to the gas furnace. Even if you know your equipment has a problem, in most situations, it is not possible to correctly diagnose the problem if the gas furnace or home has no power.
If the thermostat is blank, check to see if the thermostat has batteries, replace batteries as needed. A blank thermostat could also indicate a tripped water safety switch at the air handler. Sometimes a programmable thermostat can change your temperature setting, make sure the thermostat is set the way you intended it.
Gas to the home
Confirm that you have set up an account with the gas company and gas to the house is on. Check another gas appliance in the house to see if it works properly if it does then you know you have gas to the home.
Check filters to ensure they are clean. Some systems can have multiple air filters inside the house, or you can have a single air filter located at the furnace).
Tripped water switch or full condensate pump
While at the furnace/air handler check to see if there is a pan under the furnace. For those that find a pan, check to see if there is water in the pan. For condensate pans with water, you can remove the water and clear the drain line; this may restore the system to normal operation. If there is a condensate pump, check to confirm the condensate pump isn’t full to the top with water. A pan with water in it or a full condensate pump can turn off the equipment to protect from water damage. Do not bypass safety switches or water could cause damage to the home.
Tripped circuit breaker
Check your breaker panel for a tripped breaker, reset a tripped breaker (If the breaker trips immediately, call for service). Wait 5 minutes, if the equipment turns back on normally, you may still have a problem, if the breaker trips again, call for service.
Reset power to the furnace/Air Handler
While at the furnace, check for a light switch near or attached to the gas furnace (looks just like a regular light switch), this is the power disconnect, turn the power off to the gas furnace and back on. Some gas furnace/Air handler disconnects are located in your breaker or fuse panel if you do not see one at the gas furnace. If you have an air handler the disconnect will look different it will look like the grey rectangular box outside next to the condenser. Did the gas furnace turn on after resetting the power? (Could take up to 5 minutes). And if you’re not comfortable touching anything electrical, don,t and contact a professional. Gas heating repair specialist.
Reset power to the condenser
Similar to the above there should be electrical conduit going from the air conditioner outside into a rectangular box, open the box and there should be a handle, reset power by pulling out the air handler, waiting 30 seconds and plugging it back in.