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Intertherm Central air conditioner won't turn off

Won’t your Intertherm central air turn off? A shorted contactor or a bad wall thermostat or thermostat wiring is the most likely cause, keeping a cooling signal on the yellow (Y) terminal even after the thermostat is set to Off. A shorted furnace control board or main control board can cause the same problem, though it is a less common cause, by continuing to send voltage to the outdoor condensing unit and making the air conditioner run constantly. Next, check the wall thermostat or thermostat wiring. A stuck contact between the common "C" and yellow "Y" thermostat wire terminals can keep signaling the contactor to run; with power disconnected, use a multimeter to test for continuity while the thermostat is set to Off. A shorted contactor is less common but can keep the condensing unit energized after the control signal stops. This central air conditioner repair involves control-board diagnostics and 240-volt equipment. Shut off power at the disconnect box and circuit breaker before inspection, and have a licensed HVAC technician handle energized testing or contactor replacement if you are not qualified. Enter your Intertherm model number to find the exact replacement control board, thermostat, wall thermostat, or contactor for your system.

01 - Intertherm Central Air Conditioner Control Board

If the furnace control board has a short, it may be providing continuous voltage to the central air condensing unit preventing it from turning off. Inspect the control board for any damage and replace if necessary.

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Common

02 - Intertherm Central Air Conditioner Main Control Board

If the furnace's main control board has a short, it may be providing continuous voltage to the central air condensing unit preventing it from turning off. Inspect the control board for any damage and replace if necessary.

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Common

03 - Intertherm Central Air Conditioner Wall Thermostat

The wall thermostat has electrical contacts that send signal voltage back to the control board and the condensing unit's contactor to run the central air system. If the contact that controls the contactor sticks closed, it will send continuous voltage to the contactor, causing the central air system to run continuously. To determine if the thermostat is defective, use a multi-meter to test it for continuity. If the wall thermostat shows continuity between the common (“C”) and yellow (“Y”) thermostat wire terminals when the thermostat is in the off position, the thermostat has failed and will need to be replaced.

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Common

04 - Intertherm Central Air Conditioner Wifi Thermostat

The WiFi thermostat has electrical contacts that send signal voltage back to the control board and the condensing unit's contactor to run the central air system. If the contact that controls the contactor sticks closed, it will send continuous voltage to the contactor, causing the central air system to run continuously. To determine if the thermostat is defective, use a multi-meter to test it for continuity. If the WiFi thermostat shows continuity between the common (“C”) and yellow (“Y”) thermostat wire terminals when the thermostat is in the off position, the thermostat has failed and will need to be replaced.

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Common

05 - Intertherm Central Air Conditioner Contactor

The furnace control board sends a low voltage signal to the contactor. When the contactor receives the signal from the control board, it closes the circuit, sending voltage to the condensing unit components. If the contactor has shorted, it can send continuous voltage to the condensing unit's components resulting in the central air system not turning off. To determine if the contactor is at fault, use a multimeter to test the contactor for a short. If the contactor has shorted, replace it.

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Less Common

Frequently Asked Questions

Why won't my Intertherm central air conditioner turn off?

How can I test an Intertherm thermostat that will not shut off the AC?

Can a bad contactor cause an Intertherm AC unit to run constantly?

Could the Intertherm control board be making the air conditioner run continuously?

How do I find the correct Intertherm part for an AC that will not turn off?

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