Furnace Repair You Can Do Yourself
It seems that whenever you have a problem with your conventional or high-efficiency furnace, it is when it’s coldest outside. The issues can run from the simplest to the most complicated, but in some cases you can answer for yourself the question, “Why is it so cold in the house?” Or at least you can eliminate some causes before you need to call an HVAC (Heating/Ventilation/Air Conditioning) professional.
So let’s take a look at 19 of the most common gas furnace problems and some tips for how you can take steps to warm up again (note that in some cases the best step is to call a licensed HVAC professional):
Thermostat is off
Furnace circuit breaker tripped
Safety switch tripped
Clogged filter
Objects are obstructing proper furnace operation
Burners contamination
Furnace blower requires lubrication
Bad limit switch
Faulty ignition or pilot control
Furnace turns on and off too quickly
Furnace isn’t blowing air
Furnace is constantly running
Furnace and/or ductwork makes noises
Blocked vents
Intake/exhaust vent blockage
Dirty flame sensor
Gas supply issue
Gas leak
Old furnace needs replacement
1. Thermostat is off
Sometimes the simplest explanations provide the most satisfactory results. You can save yourself the embarrassment, not to mention the cost, of a service call when the only problem is that your thermostat is off.
Follow this checklist to ensure your heating problem isn’t something easily remedied by simply making sure your thermostat is turned on.
- Look for dust or debris in the thermostat and clean out potential clogs.
- Is the thermostat programmable? If so, does it display the right time and day? Power shortages or low batteries can upset timer settings, so that a thermostat isn’t turning on because it is set to the wrong time of day.
- Replace the battery (if the thermostat is battery-operated and not hard-wired to the house electrical system). If you aren’t changing the thermostat battery at least once a year, this is a likely cause of the thermostat going off. In most cases, a flashing light indicates a low battery level.
- Check the furnace breaker. See the next tip below.
2. Furnace circuit breaker tripped
If the thermostat is working and the Heat setting is on, move the temperature dial up and down a few degrees. If the heat still isn’t coming on, go to the circuit breaker panel (usually in the basement or a utility room). Find the circuit breaker for the furnace. If it tripped, flip the breaker back and forth and then make sure it is in the On position. If the breaker does not remain in the On position or particularly if it is hot and you smell something burning, you have a bad circuit breaker that needs replacement.
If the breaker is on, and you still don’t have heat, it is possible the circuit breaker is still bad even if it doesn’t appear so. Another possibility is the circuit itself is bad.
You could check this using a digital multimeter. If you don’t have one handy, we don’t recommend you go out and buy one. Our guess is you probably haven’t worked on an electrical system before and probably don’t feel comfortable starting now. This task is best left to a certified electrician. But before you call an electrician, check out the remaining tips to be sure that’s the actual problem.
3. Safety switch tripped
Check the safety switch on the furnace door. The purpose of this switch is to prevent the fan and burner from operating when the door is opened. If the switch is “popped,” push it back in and see if it remains in. If not, it needs replacement.
You could install the switch yourself. But if you don’t feel particularly handy or comfortable with doing wiring, it’s best to contact your HVAC professional.
4. Clogged filter
The furnace filter looks like a fabric grate, located in either the intake to the furnace or the furnace itself. The filter traps dirt and debris so it doesn’t circulate throughout your home. A clogged and dirty filter, however, impedes furnace operation and in many cases is the cause of insufficient heating. It is also the cause for higher utility bills because the furnace expends more energy trying to deliver conditioned air when the filter is clogged.
Here’s something you can easily do yourself. Remove the furnace filter. Hold the filter up to the light. Can you see through it? If not, it’s dirty and needs replacement.
Better yet, avoid waiting until you have a problem; make it a habit to regularly replace the filter at least once a year, if not more frequently depending on manufacturer recommendations. Even better, an HVAC professional can perform regular maintenance that includes filter replacement, as well as checking that your furnace is operating at peak efficiency to keep you comfortable and your utility bills low. An added benefit is that regular maintenance extends the lifespan of your HVAC system.
5. Objects obstructing proper furnace operation
The furnace area usually shares storage space. Don’t let that storage get too close to the furnace. “Stuff” attracts dust and impedes airflow, which in turn affects optimal furnace operation. Above all, keep flammable materials away from the furnace.
Even if the area around your furnace is relatively uncluttered, dust still collects around it, so make it a habit to vacuum and clean regularly around the furnace. And if you haven’t cleaned and you aren’t feeling as warm as you want, cleaning around the furnace is a good way to see if that improves matters. It’s even easier than cleaning your furnace filter.
6. Burner contamination
Are your furnace burners clean? The way to tell is to remove the furnace access door and see if the burner flames are blue. If so, the burners are clean. If the flames are yellow, that’s an indication that they are dirty.
Turn the furnace completely off–both the power and the gas. Then simply vacuum around the burner assembly and the blowers.
Dust usually collects during the summer when the burners aren’t being used. So you might want to make a habit of cleaning them right before the heating season begins. If you aren’t in the habit, sign up for a regular furnace maintenance plan that includes this service.
7. Furnace blower requires lubrication
Another aspect of regular furnace maintenance is to lubricate the furnace blower. The purpose of the blower is just what the name implies–to blow conditioned air from the furnace and distribute it throughout your house. Like any mechanical part, yearly lubrication extends the life of your furnace and ensures heat is properly distributed.
A sure sign of a blower that needs lubrication is if your furnace makes unusual noises when it starts up. If you feel sufficiently handy, you could do the lubrication yourself. This requires removing the furnace access door, unbolting the blower motor, and applying a few drops of oil to the motor and shaft ports. See these full instructions on how to oil a furnace blower motor. Otherwise, your HVAC professional lubricates the blower as part of your regular furnace maintenance plan.
8. Bad limit switch
If your blower is running continuously, you probably have a bad limit switch. While a faulty thermostat can also cause the blower to run, this is yet another situation where it is best to get a technician to replace either device.
9. Faulty ignition or pilot control
Many modern gas furnaces operate with electronic ignition, though there are still many units that employ a continual flame in a heating element called a pilot light. Drafts or dirt clogs can cause the pilot light to go out, in which case the pilot light requires manual relighting. Electronic ignition largely eliminates this problem; however, nothing is foolproof and faults with the ignition system do still occur.
An improperly functioning ignition system impairs the ability of the furnace to properly heat your home. If you have a pilot light, follow the manufacturer directions to relight it. If it is electrical ignition, call for HVAC service.
10. Furnace turns on and off too quickly
If the furnace is turning on and off too quickly, the first thing to check is the air filter. Dirty and worn-out filters are a primary cause of this issue. If the filter is still clean, or if you replace it and you still have the problem, the issue is probably with the blower motor and belts. Call an HVAC service technician.
11. Furnace isn’t blowing air
There are any number of reasons why a furnace does not blow air. The thermostat, blower motor, run capacitor, furnace control board, and/or transfer are potential sources of the problem. None of these are issues the average homeowner has the skills to diagnose. Call an HVAC service technician.
12. Furnace runs constantly
The first thing to do if your furnace runs constantly is check to make sure your thermostat isn’t set to “continuous fan.” If it isn’t, try lowering the temperature to see if that corrects the issue.
Otherwise, a furnace that doesn’t shut off is a furnace in need of repair. Call an HVAC service technician.
13. Noisy fan and/or ductwork
There is some noise associated with furnace start-up, particularly with older furnaces. In addition, ductwork sometimes expands and contracts as it heats and cools, causing popping or pinging noises. However, if you’re hearing some new and unusual noises—squealing, rumbling, or rattling—from the furnace and/or ductwork, it indicates something is wearing out or is loose.
While you could troubleshoot the underlying cause of the noise problem yourself, an HVAC professional can do this faster and with the capability to correct it quickly and properly.
14. Blocked vents
Here’s one that’s “easy peasy.” Take a walk through your house to see if any of your vents are blocked by furniture, toys, or anything that can prevent heat flow.
15. Intake/exhaust vent blockage
Another vent to check is the one from the furnace to the outside of the house (though not all furnaces have this kind of vent, it’s pretty obvious if they do). Check to see if leaves or other objects are blocking this vent, and remove them. The best way to ensure debris doesn’t get inside the vent is to cover it with ½-inch mesh. If you have ice in the intake or exhaust vent, call an HVAC professional.
If you also have an outside heat pump, the same principle applies to keeping the area around it clean.
16. Dirty flame sensor
The flame sensor is typically a rod located near the back of the furnace, close to the burner. While the sensor safeguards against improper fuel combustion, a dirty sensor can affect furnace operation. Over time, oxidation or carbon buildup on a dirty flame sensor can cause serious furnace damage and malfunction. This is yet another reason to regularly clean around the furnace to prevent dirt and debris from entering your system, as much as possible.
To clean what looks like a dirt flame sensor, turn off the power to the furnace, remove it if possible and gently remove any dust or residue. However, the best way to determine if a dirty flame sensor is causing a furnace malfunction is to perform a micro amp draw reading. An HVAC technician can perform this test and clean or replace the flame sensor if necessary.
17. Gas supply issue
Sometimes if we are not paying attention, things get knocked about and something inadvertently gets closed when it shouldn’t. Such is the case with the gas supply line, particularly if both the furnace and the hot water heater are not delivering heat.
Check the entire gas line from the main inlet to ensure the Valve wasn’t turned off. If that’s the source of the problem, it is another simple fix that avoids the cost of a service call.
18. Gas leak
What’s not a simple problem, and is a potentially hazardous one, is if you smell a gas odor. A gas leak can impair furnace operation, but the larger issue is safety. Call your gas utility company immediately and leave the house until they locate and repair the source of the leak.
19. Old furnace needs replacement
Nothing lasts forever, and your furnace is no exception. The lifespan of a well-maintained furnace is anywhere from 15 to 20 years and possibly longer. If you have a furnace older than that, or even an older model that is inefficient, it is time for a new, more energy-efficient model. Your investment in a new furnace pays off not only in better comfort levels, but lower utility bills.
Your HVAC Partner
If all this seems a bit overwhelming, we here at Ongaro & Sons can quickly determine why your furnace isn’t working properly and design a cost-effective solution that best meets your needs and lifestyle. We’ve been in business over 90 years, providing high-quality service using only the highest quality equipment. Our 100% guarantee ensures your complete satisfaction. We also offer financing that fits any budget.
Ongaro & Sons is a licensed state contractor and our qualified technicians are insured. Our goal is to make your home more comfortable, more energy-efficient, and more affordable with lower utility bills.
Contact Ongaro & Sons today if you need a furnace repair or replacement. If it’s an emergency, call us at 707-675-0947. We look forward to serving you.