The contactor is an electrically controlled switch that sends line voltage to the compressor and outdoor fan. Burned or welded contacts can stop operation or keep equipment running.

Read the complete guide → Airflow & Motors

What Are Signs of a Bad Blower Motor?

The indoor blower moves air through the filter, furnace or air handler, coil, ducts, and rooms. Failure can cause weak airflow, freezing, overheating, and loss of comfort.

Read the complete guide → Airflow & Motors

What Is a Bad ECM Blower Motor?

An ECM blower uses electronic controls to vary speed and maintain programmed airflow. Problems can involve the motor, module, wiring, controls, or duct resistance.

Read the complete guide → Airflow & Motors

What Does a Dirty Evaporator Coil Do?

A dirty indoor coil restricts airflow and insulates the heat-transfer surface. The result can be weak cooling, high energy use, freezing, odor, and water problems.

Read the complete guide → Airflow & Motors

What Does a Dirty Condenser Coil Do?

The outdoor coil must reject heat to outside air. Dirt, cottonwood, grass, and debris raise pressure and temperature and make the compressor work harder.

Read the complete guide → Common Symptoms

What Is HVAC Short Cycling?

Short cycling means the equipment starts and stops more frequently than intended. It reduces comfort, wastes energy, and increases wear.

Read the complete guide → Heat Pumps

What Is a Bad Heat Pump Reversing Valve?

The reversing valve redirects refrigerant so a heat pump can switch between heating and cooling. Failure can leave the system stuck in one mode or operating poorly.

Read the complete guide → Heat Pumps

What Is a Bad Heat Pump Defrost Board?

The defrost control decides when the outdoor coil needs to be warmed to remove frost. Failure can cause heavy icing or unnecessary defrost cycles.

Read the complete guide → Heat Pumps

Why Is My Heat Pump Covered in Ice?

Light frost can be normal during heating. Thick ice that does not clear blocks airflow and may indicate a defrost, refrigerant, fan, sensor, or drainage problem.

Read the complete guide → Electrical & Controls

How Do I Know If My Thermostat Is Bad?

A thermostat senses temperature and sends control signals. Problems may involve the thermostat, wiring, configuration, power source, or equipment controls.

Read the complete guide → Refrigeration & Compressors

What Is a Refrigerant Restriction?

A restriction limits refrigerant flow through a filter-drier, metering device, distributor, capillary tube, or damaged line. It can look like low refrigerant.

Read the complete guide → Refrigeration & Compressors

What Does a Compressor Shorted to Ground Mean?

A compressor shorted to ground has lost internal electrical insulation, allowing a winding to contact the shell or ground path. This is usually a serious failure.

Read the complete guide → Common Symptoms

Why Is My AC Blowing Warm Air?

Warm air can come from thermostat settings, outdoor-unit failure, low airflow, a frozen coil, low refrigerant, a restriction, or a compressor problem.

Read the complete guide → Electrical & Controls

Why Does My HVAC Breaker Keep Tripping?

A breaker trips to protect wiring and equipment from excessive current or a fault. Repeated resetting is unsafe and does not fix the cause.

Read the complete guide → Airflow & Motors

What Is HVAC Static Pressure?

Static pressure is the resistance the blower must overcome to move air through filters, coils, ducts, grilles, and registers.

Read the complete guide → Refrigeration & Compressors

What Is Superheat in HVAC?

Superheat is vapor temperature above saturation temperature. It helps evaluate evaporator feeding and compressor protection.

Read the complete guide → Refrigeration & Compressors

What Is Subcooling in HVAC?

Subcooling is liquid refrigerant temperature below saturation temperature. It helps show whether solid liquid reaches the metering device.

Read the complete guide → Furnaces

Why Is My Furnace Blowing Cold Air?

Cold air from a furnace can be normal briefly at startup or shutdown, but sustained cold airflow may involve ignition, fuel, airflow, control, or safety problems.

Read the complete guide → Furnaces

Why Is My Furnace Short Cycling?

A furnace that repeatedly starts and stops may be overheating, losing flame, receiving bad thermostat signals, or encountering a venting or safety problem.

Read the complete guide → Mini Splits

Why Is My Mini Split Leaking Water?

Water from an indoor mini-split head usually points to drain blockage, poor slope, pump failure, dirty coils, icing, or installation problems.

Read the complete guide → Mini Splits

Why Does My Mini Split Smell?

Odors can come from microbial buildup, a dirty blower wheel, drain issues, absorbed household odors, overheating electronics, or outside air pathways.

Read the complete guide →

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Frozen CoilWhy Is My Evaporator Coil Frozen?→ System OperationWhat Is HVAC Short Cycling?→ AC TroubleshootingWhy Is My AC Blowing Warm Air?→

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Refrigeration & Compressors

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CompressorWhat Is a Bad HVAC Compressor?→ CompressorWhat Does a Compressor Shorted to Ground Mean?→ RefrigerantWhat Does Low Refrigerant Mean?→ Metering DeviceWhat Is a Bad TXV?→ RefrigerantWhat Is a Refrigerant Restriction?→ Technician MeasurementWhat Is Superheat in HVAC?→ Technician MeasurementWhat Is Subcooling in HVAC?→

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Electrical & Controls

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ElectricalWhat Is a Bad HVAC Capacitor?→ ElectricalWhat Is a Failed HVAC Contactor?→ ElectricalWhy Does My HVAC Breaker Keep Tripping?→ ControlsHow Do I Know If My Thermostat Is Bad?→

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Airflow & Motors

5 articles

Blower MotorWhat Is a Bad ECM Blower Motor?→ Blower MotorWhat Are Signs of a Bad Blower Motor?→ AirflowWhat Is HVAC Static Pressure?→ Coil & AirflowWhat Does a Dirty Evaporator Coil Do?→ Outdoor CoilWhat Does a Dirty Condenser Coil Do?→

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Heat Pumps

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Heat Pump TroubleshootingWhy Is My Heat Pump Blowing Cold Air?→ Heat Pump TroubleshootingWhy Is My Heat Pump Covered in Ice?→ Heat Pump ComponentWhat Is a Bad Heat Pump Reversing Valve?→ Heat Pump ControlsWhat Is a Bad Heat Pump Defrost Board?→

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What Is a Bad HVAC Compressor?

What Does Low Refrigerant Mean?

What Is a Bad TXV?

Why Is My Evaporator Coil Frozen?

Why Is My Heat Pump Blowing Cold Air?

What Is a Bad HVAC Capacitor?

What Is a Failed HVAC Contactor?

What Are Signs of a Bad Blower Motor?

What Is a Bad ECM Blower Motor?

What Does a Dirty Evaporator Coil Do?

What Does a Dirty Condenser Coil Do?

What Is HVAC Short Cycling?

What Is a Bad Heat Pump Reversing Valve?

What Is a Bad Heat Pump Defrost Board?

Why Is My Heat Pump Covered in Ice?

How Do I Know If My Thermostat Is Bad?

What Is a Refrigerant Restriction?

What Does a Compressor Shorted to Ground Mean?

Why Is My AC Blowing Warm Air?

Why Does My HVAC Breaker Keep Tripping?

What Is HVAC Static Pressure?

What Is Superheat in HVAC?

What Is Subcooling in HVAC?

Why Is My Furnace Blowing Cold Air?

Why Is My Furnace Short Cycling?

Why Is My Mini Split Leaking Water?

Why Does My Mini Split Smell?

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