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AIR CONDITIONING BASIC TROUBLESHOOTING
First make sure that the thermostat is set lower than the actual room temperature. The
selector switch must be on "cool". If the thermostat is programmable, be certain it has
Check for power by moving the fan switch from "auto" to "on". If the blower runs, there is
power. If nothing happens, a control is burned out or power is disconnected. If the system
uses a furnace for heat, check that the emergency switch is on. If you are familiar with
the fuse or circuit breaker panel, check for blown fuses or tripped breakers. Correct the
problem one time only. If it repeats, call for service.
With the selector switch on cool and the fan switch on auto, move the thermostat well
below room temperature. If the blower runs but the condenser(outdoor unit) does not,
check the circuit breaker panel. If the breaker is on, examine the condenser. Some
have a high pressure cut out. It is a button sticking out of the cabinet, usually near the
refrigerant lines. Push it in as far as it will go to reset it.
If both units are running and no cooling is taking place, touch the larger of the two
copper lines exiting the condenser. If it is warm, the system is out of freon or the
compressor is down. If the line is frozen or iced over, there is an air flow problem inside,
such as clogged filter or too many registers closed or an object covering the return duct.
A low freon charge will also cause a freeze-up. Shut the system down and let it thaw out
completely. If it freezes up again, call for service.
If the unit is in the basement and has a condensate pump, the control wire for the
condenser might be wired through a safety switch on the pump. Check to see if the
pump is plugged in and operable.
If the unit is in the attic, there could be a float switch in the air handler or in the safety pan
that will shut the condenser off if the drain is clogged. Water around the unit is evidence
of trouble. Call for service.
ELECTRIC FURNACE BASIC TROUBLESHOOTING
The thermostat must be set higher than the actual room temperature. If the thermostat is
programmable, be certain it has fresh batteries.
If there is central air, or the system is zoned, make sure the selector switch is on heat.
If you are familiar with the fuse or circuit breaker panel, check for blown fuses or tripped
breakers. Correct the problem once. If it repeats, call a serviceman.
Do not attempt to service the controls inside the cabinet. Deadly high voltage conditions
HEAT PUMP BASIC TROUBLESHOOTING
Make certain that the thermostat is set higher than the actual room temperature and the
selector switch is on heat if heat is needed, or that the thermostat is set lower than the
actual room temp and the switch is on cool if air conditioning is desired. If the thermostat
is programmable, be certain the batteries are fresh.
Test for power to the air handler by moving the fan switch from "auto" to "on". If the
blower runs, the air handler is functional. If nothing happens, check the circuit breakers
on the air handler cabinet and the breakers or fuses in the main panel. If any breakers
are tripped, reset them once. If they trip again do not reset them. Deadly high voltage
conditions exist inside the air handler cabinet and inside the access panel of the
condenser. Let a qualified serviceman open them.
If the air handler runs constantly but cannot satisfy the thermostat setting, it is possible the
backup heat is running but the condenser is not. Some condensers have the high
pressure cut-out switch externally accessible. Look for a button sticking out of the cabinet
in the vicinity of the refrigerant pipes. Press it in. If the machine starts up, the head
pressure got too high, possibly from turning on and off too quickly, too much or too little
refrigerant, or an electrical interruption. As the unit ages , the switch can weaken and
pop easily. If the condition repeats itself often, have a serviceman check it.
Because all the controls are internally mounted, and high voltage wiring is exposed,
only a serviceman should open panels.
GAS FURNACE BASIC TROUBLESHOOTING
Check that the thermostat is set higher than the actual room temperature. If you have a
programmable thermostat, make sure it has fresh batteries.
If equipped with central air, or the system is zoned, Make sure the selector switch is on
Check the emergency switch( usually a red switch plate at the top of the attic stairs or on
the side of the furnace) to see that it is on.
If you are familiar with the fuse or circuit breaker panel, see if the fuse is burned or the
breaker tripped. Correct the problem once. If it repeats, call a serviceman.
On standing pilot furnaces, the burner will not light if the pilot has gone out. If you are not
familiar with the function of the gas valve or lighting the pilot, call for service.
Furnaces with electronic ignition have a sequence of safety steps the burner takes to
light. Information is usually attached to the inside of the burner or blower access door.
Follow the procedure according to the manufacturers guidelines to avoid the risk of fire
Do not disconnect any piping to check for gas supply. An instrument is used to check for
pressure, and should be done by a qualified serviceman.
If the furnace is vented through PVC (white plastic pipe) out the side of the building,
examine the ends of the pipe or pipes outside. Blockage of any kind will cause a
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