In this two-part blog post, we examine the most common problems that we see when we go out on furnace service calls. Read on to discover the adventures our certified HVAC technicians encounter daily when trying to resolve furnace problems for our customers.
- Dirty Flame Sensor
A furnace flame sensor is a safety component located inside the burner assembly, whose job is to detect and confirm whether or not there is a flame burning inside the furnace within 10 seconds of the gas valve opening. If there is no flame detected, the flame sensor will shut off the furnace to prevent a dangerous gas leak.
One of our top complaints on furnace service calls: the customer complains that they can hear their furnace come on, and the burners fire up, but it only stays on for a few seconds. This is usually an easy one to diagnose, and usually the result of a lack of routine maintenance on the furnace. Annual furnace service prevents this issue. - Dirty Furnace Filter
The filter is in the furnace’s return duct, right before the furnace itself. The filter, which is directional, must be installed with the correct orientation. Examine the edge of the filter and you’ll see an arrow, which indicates the direction of the air flow. Another way to tell the proper orientation is to look for a mesh net on one side of the filter; this should face toward the blower motor. In an extreme instance, if the filter gets too clogged, it can get sucked into the furnace and wrapped around the motor shaft.
The furnace filter is one of the first things we check when we go on a call. Examining the filter will give us a quick indication of the current state of the furnace (i.e. whether or not the homeowner has performed regular maintenance). - High Limit Switch
Sometimes when we go out on a service call, customers complain that their furnace will light and burn for a few minutes, then cut off. Or, they complain the furnace can’t keep up when it’s colder outside. The fan continues to blow; it cools down, the furnace lights again, overheats, then cuts off. This usually indicates a faulty high-limit switch. Some furnaces have a lockout feature, that allows the furnace to start 3-5 times in a heating cycle, then will shut the furnace off for about three hours without trying to start again. - Bad Inducer Motor
The inducer assembly is a small fan located above the gas burner compartment of a furnace that pulls air through the furnace heat exchanger and sends it to the outside through a vent pipe, usually through the roof of your home. A couple of indicators the inducer motor is damaged is the homeowner doesn’t get any heat when they turn up the thermostat; or when we arrive on the service call, the inducer motor is scorching hot. Another indicator it may be bad, or headed for trouble, is if it emits a loud banging noise when the fan is bent or the door covering the inducer is bent inward. This usually indicates the inducer motor must be replaced. Sometimes, if the inducer motor won’t turn, there might be a small animal like a squirrel or mouse caught in the housing. - Bad Blower Motor
The blower motor is found at the bottom of the furnace (on a typical upflow furnace), in a large housing right next to the filter. We check the blower motor first by checking to see if the “squirrel cage” or blower wheel with spin by hand. If the motor is seized or frozen it won’t turn. We’ll know if the blower motor is bad when the homeowner says the motor has a hard time starting or they smelled an electrical burn. Closely related is the capacitor, which helps the fan a boost to start. A longtime clogged air filter or bad capacitor can cause the blower motor to go bad.
Next week, we’ll complete the list. Stay tuned!
Remember, as we get into the fall and cool weather is approaching, be sure to call Dor-Mar and schedule your annual maintenance for the safety and protection of your family and the biggest investment of your life – your home.
Schedule an appointment for your Furnace Tune-Up with us today by using our online contact form, or call one of our seven neighborhood offices.. We pride ourselves on our customer-focused service, and our reviews show it.
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