Cornerstone A/C & Heating

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Troubleshooting

No Cool / No Heat

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 fresh batteries. 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 exist.


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 heat. 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 manufacturer's guidelines to avoid the risk of fire or explosion. 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 shutdown.







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