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HomeRepair HelpIntertherm Central A/C RepairIntertherm Central air conditioner won't turn on Repair
Intertherm Central air conditioner won't turn on
Is your Intertherm central air conditioner not turning on? If the air conditioner will not start, begin with the most likely causes: a failed transformer, a defective furnace control board, dead wall thermostat batteries, or an incoming power problem. The transformer supplies the 24-volt signal that lets the thermostat activate the contactor and start the outdoor condensing unit. A control board can also prevent that signal from reaching the contactor or stop power from reaching the blower motor. If the thermostat display is blank, replace its batteries if applicable, then check the furnace or air handler for a tripped circuit breaker, blown fuse, or turned-off power switch. Less commonly, the wall thermostat or Intertherm wall thermostat may not send the cooling signal through the thermostat wire. Testing for 24 volts between the C and Y terminals requires a multimeter and electrical experience. Disconnect power before inspecting components, and leave 240V wiring, the disconnect box, contactor, and other line-voltage repairs to a qualified technician. Refrigerant work is not involved in this diagnosis, but any sealed-system repair requires EPA 608 certification. Enter your model number to find the exact Intertherm transformer, control board, thermostat, or other replacement part for your central air conditioner.
01 - Intertherm Central Air Conditioner Transformer
The furnace control board sends a low voltage signal of 24 volts to the thermostat. When the themostat cooling contacts close, a 24 volt signal is sent to the contactor coil, closing the high voltage circuit and sending power to the condensing unit components. Some furnaces have a separate transformer for the 24 volt circuit, so if the contactor is not receiving the proper voltage when the thermostat cooling contacts are closed, it's likely this transformer has failed and the component will need to be replaced.
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Highly Likely
02 - Intertherm Central Air Conditioner Control Board
If the central air condensing unit contactor is not receiving 24 volts or power is not getting to the furnace blower motor, a possible cause is a defective furnace control board. While this is not a common problem, if all other potentially faulty components are working properly, the control board should be replaced.
Highly Likely
03 - Wall Thermostat Batteries
Most wall thermostats are either powered by an enclosed battery or by the furnace or air handler transformer. If the thermostat display is dead, you can remove the thermostat cover and look for replaceable batteries. Replace the batteries if needed and check operation.
Common
04 - Incoming Power Problem
Check to see if there is power to the furnace or air handler. One or more indicator lights on the control board should be illuminated. If there is no power to the furnace or air handler, check to see if a circuit breaker has tripped or a fuse has blown. Confirm the power switch on the side of the unit is turned on.
Common
05 - Intertherm Central Air Conditioner Wall Thermostat
The furnace control board sends a low voltage signal of 24 volts to the contactor through the wall thermostat. When the contactor receives the signal from the wall thermostat, it closes the circuit, sending voltage to the condensing unit components. There should be 24 volts between the common (“C”) and yellow (“Y”) thermostat wire terminals on the furnace control board when the wall thermostat is in the cooling mode. You can check for this voltage with a multimeter. If voltage is not reaching the contactor, it's likely the wall thermostat is defective and will need to be replaced.
Less Common
06 - Intertherm Central Air Conditioner Wifi Thermostat
The furnace control board sends a low voltage signal of 24 volts to the contactor through the WiFi thermostat. When the contactor receives the signal from the WiFi thermostat, it closes the circuit, sending voltage to the condensing unit components. There should be 24 volts between the common (“C”) and yellow (“Y”) thermostat wire terminals on the furnace control board when the WiFi thermostat is in the cooling mode. You can check for this voltage with a multimeter. If voltage is not reaching the contactor, it's likely the WiFi thermostat is defective and will need to be replaced.
Less Common
Frequently Asked Questions
Why is my Intertherm central air conditioner not turning on?
How do I know if my Intertherm thermostat is not turning on the AC?
Could the Intertherm transformer or control board be causing the air conditioner not to start?
What should I check if the outdoor AC unit is not turning on but the furnace or air handler has power?
How do I find the correct Intertherm replacement part for my central air conditioner?
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