Heating and Cooling Systems
R-22 and Alternative Refrigerants
Forced-Air Heating and Furnace Repairs
or Portable Air
Cooling Capacity ||
Energy Efficiency || AC Condenser Maintenance ||
Testing and Troubleshooting ||
and Electric Attic Fans ||
Forced-Air Heating and Furnace Repairs
The following are simple
repair solutions to help you remedy some common
forced-air furnace problems:
1: No heat
The good news is when your
heating system isn’t heating, the problem is
generally due to thermostat malfunctions, a
blown fuse, tripped circuit breaker, or if you
have a combustion furnace, the pilot light has
more than likely gone out.
The following are some quick checks for
when your heat doesn't come on even after you
have adjusted the thermostat to a setting above
the current room temperature:
Make sure that you have the thermostat
is set to "Heat.”
This is for those of you who have a
combined heating and cooling system.
We receive approximately 30 calls a year
because of this simple problem.
This usually occurs when one person in
the home has turned off the heat for one reason
If the thermostat isn't turn to Heat,
please do so.
If you still are not getting heat, then
go to step 2.
Check the furnace's circuit breaker to
ensure that it is in the on position or that
the fuse has not blown.
Make sure that you check both the main
electrical panel and any secondary sub-panels
that you may have that supplies power to the
the circuit is blown or is tripped, then reset
the breaker or replace the fuse.
However, if the circuit trips again or
the fuse blows again, then call an electrical
contractor as the problem is probably is a
short in the electrical system that provides
power to the furnace.
Do not attempt to repair the short
yourself unless you are an experienced
If the circuit is not tripped or the
fuse blown, then make sure that the furnace's
power switch is turned on.
If the power switch is not on, turn it
will take a couple of minutes for your furnace
If this does not work then proceed to
If after all of this, the problem might
be that the blower motor may need to be reset.
This could be because of an overload.
Look for a RESET button that is usually
located near the blower motor's housing. Once you have located the reset button, press it.
If there is no response, allow the motor
to cool down for approximately 30 to 45
minutes, and then try the RESET button again.
If at this time you still do not have
heat, turn off the power to the furnace at the
main electrical panel or sub-panel.
Check to see if there is a fuse in the
If there is one there, see if it is
it has, replace the fuse, making sure that you
follow the instructions in your owner's manual.
If you have misplaced the owners’
manual or are not sure about what it will take
to replace the fuse, than we strongly suggest
that you call a furnace repair technician.
If you have a gas furnace, and are
getting heat, then check to see if the pilot
light has gone out or if the gas valve has been
Check the furnace's ignition, as
In order for your gas- or oil-burning
furnace to heat, it must be receiving fuel.
If you have a gas-fired furnace, make
sure the valve on the gas pipe is turned on. The handle should be in line with the gas pipe.
If you have an oil furnace, check your
Check the furnace to see if the pilot
light is lit.
If it is not lit, then follow the
instructions in your owner's manual or the
instructions posted inside the furnace cabinet
for pilot light information.
If it still doesn't work, be sure the
thermostat isn't faulty.
for troubleshooting a Thermostat.
If after trying each of these steps,
your furnace still does not work, call a
heating contractor or furnace repair
2: Insufficient heat
If your furnace is
operating, but providing little heat make sure
that there isn’t anything blocking the warm
Check to see if your thermostat is set
If it is, then raise the set temperature
5 degrees and waiting a few minutes to see if
that improves the amount of heat in the room.
Make sure that all of the room’s
heating registers are open.
Check the furnace filter and if it is
dirty, clean it if you have reusable filter, or
replace it if you use a disposable filter.
after following these simple steps, your
furnace still does not work, call a furnace
repair technician to check out your system.
3: Furnace constantly turns on and off
If your furnace continues
to run or cycles off and on too frequently,
then the problem will often be with the
This is especially true if you have a
for troubleshooting a Thermostat.
If you have an
electric-resistance furnace, or heat pump that
frequently turns off and on, the problem is
often due to the unit overheating because of a
clogged filter or blower, which is
Cleaning or replacing the filter.
If this does not correct the problem,
then contact a furnace repair technician.
4: Dramatic changes in room temperature
If the room temperature
drops more than about 3 degrees, between the
time your furnace shuts off, and the time it
turns back on, or it the room temperature
raises more than 3 degrees from what the set
temperature is set on the thermostat, it
generally means that the furnace isn't cycling
on and off often enough. This
problem is usually caused by the thermostat
being improperly calibrated or installed where
it doesn't sense a proper sampling of room air.
Contact a furnace repair technician.
5: Blower runs continuously
If your blower
continuously runs, the problem may be caused by
two things, first the problem may be due to the
thermostat mounted on the wall, or second the
limit switch located on the furnace.
The limit switch is usually located on
the furnace right below the plenum, which is
the box that distributes the heated air to the
job of the limit switch is to shut off the
furnace if the air inside the plenum gets too
Another reason for the
blower to run continuously is if the
"Fan" switch on the thermostat has
been turned on.
If the fan switch is turned on, then
turn it to the “Off" or "Auto”
However, if the switch is set to the off
or auto position, then your furnace's limit
switch must be adjusted.
If you have are handy with this type of
repair, follow the instructions in your owner's
manual to reset the pointers on the fan side of
the limit control.
However, if you are not handy or
comfortable with this type of repair, then we
strongly suggest that you call a furnace repair
technician to adjust the limit switch.
6: Noise Furnace
If you hear squealing
sounds coming from your forced-air furnace,
this is often due to the belt that connects the
motor to the fan slipping.
In many instances, the belt has been
improperly aligned or is worn and in need of
To replace or properly align the belt,
follow the instructions in your owner's manual. If you do not have or have misplaced your owner’s manual,
contact the manufacturer, and request one.
Replacing the belt will
involve removing the access panel, loosening a
few bolts, which secure the blower motor at the
proper tension, and then replacing, and
aligning the belt.
Even if the belt appears in good
condition, it is a good idea to remove the belt
and purchase a new replacement at the hardware
you replace the belt, make sure that you do not
over-tighten it as this can cause the motor
bearings to wear out quickly.
After you have replace the
belt, if your furnace starts making rattling
noises, then check the cover panels to ensure
that it is screwed on tight.
However, if you hear a
grinding noise coming from the blower, turn off
your unit and call a furnace repair technician.
A grinding noise coming from the blower
usually means the motor's bearings are shot.
7: Noisy Air ducts
Having noisy air duct is a
more common problem than most people thing.
The reason is that most heating ducts
are metal, which will expand and contract as it
heats up and then cools down.
Another reason for air ducts being noisy
is they will conduct sounds from the
air-handling unit to your rooms.
If you want quieter air ducts, consider
having a heating contractor insert flexible
insulation ductwork between the furnace or air
conditioner and the ductwork runs, this will
reduce the amount of noise coming from your air
Popping noises coming from your ductwork is often
caused by thermal expansion.
However, it can also be due to air
blowing past a loose flap of metal.
To discover what is causing the popping
sound, follow the duct runs, carefully
listening for the sound.
Once you have located where it is coming
from, you want to make a small dent in the
By making a small dent, you will make a
more rigid surface that will be less likely to
move when it is heated and cooled.