Ductless mini-split indoor head mounted high on a wall
7 components covered

Field manual · Air Conditioner

Goodman / Amana GSX air conditioner and GSZ heat pump outdoor units: quick sheet

Covers: Goodman GSX (cooling-only condensers) and GSZ (split heat pumps), single-stage, 13-16 SEER class, plus Amana/Daikin badged equivalents. Heat pumps use a time-temperature defrost control board with selectable intervals.

Single sourceBrands: Goodman, Amana, Daikin7 components

Basic single-stage outdoor units: a contactor, a dual run capacitor, a PSC condenser fan motor and a single-stage compressor. GSX condensers usually have no control board; the thermostat's Y signal pulls in the contactor directly. GSZ heat pumps add a defrost board, a reversing valve and a defrost sensor on the outdoor coil.

Safety first

  • Refrigerant work (gauges, charge, recovery, brazing, compressor replacement) is blocked: refer to an EPA 608-certified technician.
  • Turn off the disconnect and verify 0 V; discharge capacitors before touching.
  • Do not run the compressor with the condenser fan stopped.

How it works

Cooling: the indoor thermostat sends 24 V on Y to the contactor coil (through any pressure switches or board). The contactor closes and powers the compressor and fan motor, both started through the dual run capacitor.

Heat pump reversing valve: on these units the valve is normally energized in cooling (O terminal). With no 24 V on O the unit heats.

Defrost (GSZ): the board counts compressor run time in heat mode only while the coil sensor reads cold. When the selected interval (commonly 30, 60 or 90 minutes) expires with a cold coil, it shifts the reversing valve to cooling, stops the outdoor fan and brings on auxiliary heat. Defrost ends when the coil warms enough to open the sensor or at a maximum time limit.

A TEST (speed-up) jumper position or pins on the defrost board lets the tech force a defrost to check the board, valve and fan relay.

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Ductless mini-split indoor head mounted high on a wall by NEOSiAM, Pexels License

Diagnostic guides for this appliance

Guide · Air Conditioner

PTAC not cooling (fan runs, air not cold)

Most PTAC no-cool calls are airflow (filter, coils), a wrong control setting or a failed compressor start component. Rule those out before suspecting the sealed system.

6 steps ~60 minmoderate
Guide · Air Conditioner

PTAC not heating (electric heat or heat pump)

PTACs heat with electric strip heat, a heat pump, or both. Heat pump models switch to strip heat in cold weather. Check settings, then the heater element and its limits, then the reversing valve.

5 steps ~60 minmoderate
Guide · Air Conditioner

PTAC error codes: how to read and clear them

Most PTAC brands store fault codes that can be shown with a button combination on the control (for example GE Zoneline uses a MODE + another key sequence on some models). Read the active code, fix the cause, then clear it.

4 steps ~20 mineasy

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Carrier / Bryant split AC and heat pump outdoor units (single-stage): quick sheet

Carrier, Bryant and Payne single-stage split air conditioners (24-series style) and heat pumps (25-series style) with conventional 24 V control. Communicating Infinity/Evolution and variable-speed inverter units use different boards and are not covered.

7 components5 common failuresCarrier, Bryant, Payne
Manual · Air Conditioner

Window air conditioner (incl. U-shaped inverter): field service manual

Standard box-type window units with mechanical or electronic controls and U-shaped inverter window units (Midea U style and similar saddle designs). Series names only; confirm details on the model's tech sheet.

9 components8 common failuresFrigidaire, GE, LG, Midea
Manual · Air Conditioner

Portable air conditioner (single and dual hose): field service manual

Floor-standing portable units with one or two window hoses, internal condensate tank or pump, and auto-evaporation in cooling mode.

6 components6 common failuresGE, LG, Frigidaire, Midea, Haier
Goodman / Amana GSX air conditioner and GSZ heat pump outdoor units: quick sheet · OnCall Tech