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HomeRepair HelpMars Central A/C RepairMars Central A/C Condensing unit does not run Repair
Mars Central Air Conditioner Condensing unit does not run
When your Mars central air conditioner's condensing unit does not run, A bad run capacitor or a tripped circuit breaker or blown fuse is the most likely cause. A failed compressor is a possible but less common cause. If the compressor, condenser fan motor, and capacitor appear to operate correctly, the compressor can be checked for electrical continuity, but replacement should be handled by a qualified HVAC technician. A failed wall thermostat can also prevent the furnace and outdoor condensing unit from starting. Next, inspect the condenser fan motor and fan motor, since seized bearings or an open electrical circuit can keep the outdoor AC unit from running; the condenser fan blades should rotate freely by hand with power disconnected. If the unit has power and the contactor is working but neither the compressor nor fan runs, a sealed-system problem, such as low refrigerant causing the low pressure switch to trip, is possible. A faulty high pressure switch or low pressure switch is less common. Testing or replacing 240-volt components requires appropriate training, and any refrigerant, pressure switch, or sealed-system repair requires EPA 608 certification and a licensed HVAC technician. Enter your Mars model number to find the exact replacement part for your central air conditioner.
01 - Mars Central Air Conditioner Compressor
Central air conditioners use a compressor to pump refrigerant through the condenser coils located in the outside condensing unit and through the evaporator coils mounted on top of the furnace or air handler. While it's not a common problem, if the compressor fails, the condensing unit will not run. You can use a multimeter to test the compressor for electrical continuity, a continuous electrical path present in the component, to help determine if the compressor is faulty. If all other potentially defective components, such as the capacitor and condenser fan motor, are operating properly, then a qualified technician should ...
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Highly Likely
02 - Mars Central Air Conditioner Wifi Thermostat
The WiFi thermostat has contacts in it that control the furnace. If the contact fails it can result in the furnace and the condensing unit to not run at all.
Common
03 - Mars Central Air Conditioner Condenser Fan Motor
A faulty condenser fan motor can be responsible for the central air conditioner condensing unit not running. You can use a multimeter to test the fan motor for electrical continuity, a continuous electrical path present in the motor, to help determine if the motor is defective. You can also use the multimeter to determine if power is reaching the motor. You can also try rotating the fan blades by hand. If the blades do not turn freely, it's likely the motor bearings have seized and the fan motor will need to be replaced.
Common
04 - Mars Central Air Conditioner Fan Motor
A faulty fan motor can be responsible for the central air conditioner condensing unit not running. You can use a multimeter to test the fan motor for electrical continuity, a continuous electrical path present in the motor, to help determine if the motor is defective. You can also use the multimeter to determine if power is reaching the motor. You can also try rotating the fan blades by hand. If the blades do not turn freely, it's likely the motor bearings have seized and the fan motor will need to be replaced.
Common
05 - Sealed system problem
If the condensing unit has power to it, the contactor checks out okay, but the fan and compressor are not running, it is likely that the unit is low on refrigerant which will cause the low limit pressure switch to trip and keep the unit from running. Since diagnosing and repairing a sealed system takes specialized tools and knowledge, a qualified service technician should diagnosis and repair the unit.
Common
06 - Mars Central Air Conditioner Pressure Switch
A pressure switch is a safety device used to help prevent component and system failures. There are basically three types of pressure switches used in central air conditioning and heat pump applications: High Limit, Low Limit, and Ambient Temperature. Depending on the model, you may have one or more of these or none. The pressure switch(es) can be checked with a multimeter, referencing the wiring diagram for the circuit locations. Note: If a pressure switch needs to be replaced the refrigerant will need to be removed, requiring a qualified technician.
Less Common
Frequently Asked Questions
Why is my central AC condenser not turning on?
What should I check when the condenser fan is not running?
Can a thermostat cause the outside AC unit not to turn on?
What does it mean if the AC condenser has power but the fan and compressor do not run?
How do I identify the correct Mars central AC replacement part?
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