HVAC Troubleshooting and FAQ
Naturally, any extensive work your HVAC system may need should be performed by a licensed
professional. And, many people simply prefer to call their dealer when they are unhappy with the
performance of their system, or if the HVAC system has quit working altogether. However,
there are other people who prefer to be more hands-on.
Replace the indoor unit's air filter monthly:
Old/Dirty filters cause equipment to work harder, resulting in energy waste and possible internal
damage. If you have a reusable/washable filter, make sure that it has completely dried prior to
Inspect the blower compartment of your furnace or blower coil:
Use a vacuum to remove any dirt or dust, which can result in improper performance and low
efficiency. Make sure that the coil is dry prior to vacuuming.
Remove clutter from around the furnace or blower coil:
Items stored near the furnace are fire hazards. They may also obstruct combustion air supply.
This could cause complete combustion and the production of carbon monoxide gas. Your furnace
or blower coil could be located in a closet, attic or basement. Removing clutter applies to your
equipment no matter where it is located.
Check the chimney or flue pipe connections for tightness, blockages or loose connections:
Your gas furnace flue pipe must remain tightly connected and free of blockage for the furnace to
operate correctly. If repairs are required, contact your local dealer to schedule the repairs.
Set the thermostat on "HEAT" and move the temperature setting above room
temperature: Listen for any unusual sounds and call your local dealer if you suspect problems.
Keep return registers/grilles clear of obstructions:
The return register/grille must remain free of obstructions such as furniture, lint, dust or pet hair
for the system to operate properly.
Clean humidifier reservoir regularly:
If your home comfort system includes a humidifier, it may be necessary to clean the water
reservoir to prevent mold or mildew buildup.
Trim brush and shrubbery near outdoor units to prevent airflow obstruction:
It is important to provide unrestricted airflow to the outdoor unit. Leaves, trash or shrubs
crowding the air conditioner or heat pump cause the unit to work harder and use more energy.
Also remove any debris that may have collected around the unit.
Clean outdoor coil:
The outdoor coil on an air conditioner or heat pump can sometimes become obstructed by grass
clippings, leaves, dust, etc. If this happens, using a garden hose, gently run water over the coil,
removing unwanted obstructions.
Make sure outdoor unit remains level:
Ground shifting or settling can cause an air conditioner or heat pump to sit in an uneven position.
If this happens, re-level the unit to make sure water/moisture drains from the cabinet properly.
The following is a checklist of things you can check prior to calling your dealer for service. If
neither the maintenance tips above nor the troubleshooting checklist below corrects the problem,
you will need to contact your local dealer for service. Please write down the model and serial
number of your air conditioner or heat pump and your furnace or blower coil.
1. Check to see that electrical disconnect switches are ON.
2. Make sure the thermostat temperature selector is properly set.
3. The thermostat system switch should be in the on position.
4. Replace any blown fuses or reset "tripped" circuit breakers.
5. Make sure unit access panels are in place.
6. Clean or replace air filter.
The following information can help guide you in your approach:
What maintenance can I do myself?
What routine maintenance do I need help with?
Can I troubleshoot before calling a dealer?
Should I repair or replace old equipment?
With the proper maintenance and care, your Carrier
equipment will operate economically and dependably. There are a few simple, routine
maintenance operations you can do to help ensure the best performance and comfort from your
Before you perform any kind of maintenance, consider these important safety precautions.
Disconnect all electrical power to the unit before removing access panels to perform
maintenance. Please note that there may be more than one power connection switch.
Check the air filter in your furnace or fan coil every 3 to 4 weeks. A dirty filter will cause
excessive strain on your furnace, air conditioner or heat pump. Replace your filter when
necessary, or clean it if you have the reusable type. (If you have a reusable filter, make sure it’s
completely dry before you re-install it.) The prefilter and collection cells of an electronic air
cleaner should be cleaned at least two or three times per year.
Clean dust off of your indoor coil. With a vacuum cleaner and soft-brush attachment, you can
remove any dust from the top and underside of the coil. Make sure you only do this when the coil
is dry. If you can’t get the coil clean this way, call your dealer for service.
Keep your outdoor condensing unit free of debris. If you keep grass clippings, leaves,
shrubbery and debris away from your outdoor unit, it should only require minimal care to operate
properly. Check the base pan (under the unit) occasionally and remove debris, to help the unit
If the outdoor coil becomes dirty, use a brush or a vacuum cleaner with a soft brush attachment
to clean the surface. To clean dirt that is deep in the coil, contact your dealer.
Take special care of outdoor condensing units in ocean environments. If your unit is located
near a sea coast, you can help preserve its optimal condition with a little extra care. Ocean mist
and sea breezes carry salt, which is corrosive to most metals. Although new Carrier units are
made out of galvanized metal and are protected by top-grade paint, you can add life to your unit
by washing all exposed surfaces and the coil approximately every three months. (Ask your
installing contractor about the appropriate interval in your area.)
Make sure your outdoor unit stays in a level position. If the support for your split-system
outdoor unit shifts or settles and the unit is no longer level, re-level it promptly to make sure
moisture drains properly out of the unit. If you notice that water or ice collects beneath the unit,
arrange for it to be drained away from the equipment.
Inspect your furnace’s combustion area and vent system before each heating season. If you
find dirt, soot or rust, your system may not operate properly or at its peak efficiency. Call your
servicing dealer and do not operate your furnace until it is professionally inspected and/or
Have oil-fired boilers inspected annually. Call your servicing dealer before each heating
season to replace your oil filter cartridge and conduct a thorough inspection of the unit’s
Clean your humidifier at the beginning of every heating season. Review your owner’s
manual for the proper procedure to clean the external and internal components of your unit. The
evaporator pad should also be replaced before each heating season. If the water in your area is
hard or has high mineral content, you may need to clean or service your humidifier more
Clean the core and air filters on a ventilator at least every three months. You can vacuum
the core of an energy recovery ventilator as long as it is dry and the outdoor temperature is
between 60 F (16 C) and 75 F (24 C). Heat recovery ventilator cores can be soaked for three
hours in a solution of warm water and mild soap and then rinsed. Ventilator air filters are
washable: just use a vacuum to remove the heaviest accumulation of dust and then wash them in
lukewarm water. Replace them after they are completely dry.
Think about how you take care of your car. Sure, most people can handle the little
stuff - checking and topping off fluids, keeping tires inflated to the correct pressure,
changing the wiper blades. But, to keep your car operating at its best, you need an
occasional tune-up from a trained professional.
Your heating and cooling system is no different. To get the most performance and
longest life from your system, it's a good idea to have a professional perform routine
checks in the spring and in the fall.
In the spring, your dealer will typically check a heat pump or air conditioner for all or
some of the following:
lubrication of moving parts
In the fall, you can expect a dealer to check your furnace in the following areas:
burner and pilot assemblies
cracks in the heat exchanger
check the pilot thermocouple
examine the filter and check vent piping
test the electronic ignition
test the fan
test the limit switch
measure manifold gas pressure
measure temperature rise
carbon monoxide test
set the heat anticipator
check and adjust belt tension
examine the draft diverter
lubricate the fan motor
The answer is, "Yes." Here are some simple procedures you can perform before going to the
expense of a service call:
Check disconnect switches (indoor and outdoor if you have a split system). Make sure
that circuit breakers are ON or that fuses have not blown.
Check for sufficient airflow. Make sure air filters are clean and that supply-air and
return-air grilles are open and unobstructed.
Check the settings on your thermostats. If you want cooling, make sure the
temperature control selector is set below room temperature and the SYSTEM switch is on
the COOL or AUTO position. If you want heat, make sure the temperature control
selector is set above room temperature and the SYSTEM switch is at HEAT or AUTO.
The FAN switch should be set at ON for continuous blower operation or AUTO if you
want the blower to function only while the unit is operating.
In addition to the routine maintenance you perform, your home comfort system should be
inspected at least once a year by a properly trained service technician. Your servicing dealer will
make sure your system operates safely and gives you the best performance at the lowest cost.
You may also want to ask your dealer about an economical service contract that covers seasonal
inspections for a flat fee.
Three main factors to consider are:
Life Expectancy of Current System
When you’re frustrated with an equipment break-down, it can be tempting to find the least
expensive "quick fix" to get on with your life in relative comfort. That "quick fix" may be the
least expensive now, but it may not give you the most value — or cost you the least — in the
Paying for repairs to an old or inefficient system often simply prolongs the inevitable. It’s almost
like putting a bandage on a serious injury. An older system that breaks down once is likely to
break down again. That means more emergency service calls or, worse yet, the risk of damage to
your home or to other components of your heating and cooling system.
There’s also an ongoing cost factor to consider. Restoring your old system will only bring it back
to its current level of energy efficiency. After you’ve recovered from the repair bills and the
frustration of system breakdowns, you still won’t save on your energy bills.
Even six-year-old heat pumps and air conditioners are considered grossly inefficient by today’s
energy efficiency standards. So are most furnaces built before 2000. So you could save up to
60% on your energy bills with new high-efficiency equipment. That’s why installing a new
heating and cooling system can actually pay for itself in energy savings within a relatively short
Looking at the Big Picture
When one component of your system breaks down unexpectedly, it’s easy to just focus on
repairing or replacing that component. But each part of your system works with the others to
boost efficiency and reliability, so it helps to keep the big picture in mind.
Replacing your old furnace with a new higher-efficiency model but leaving your old mechanical
thermostat in place, for example, won’t allow you to enjoy all the efficiency advantages the
furnace has to offer. Likewise, if you install a new furnace but don’t get a humidifier, the air may
seem cooler, forcing you to operate your new system at a higher temperature to be comfortable.
Plus, you can often save on installation costs if you have several components of your system (for
example, a furnace and an air conditioner) replaced at the same time.