Air-source heat pump outdoor unit beside a house in the snow
2 components covered

Field manual · Fundamentals

HVAC brand families: who builds Carrier/Bryant/Payne/ICP, Goodman/Amana/Daikin, Rheem/Ruud, Trane/American Standard, Lennox/Allied, York/Coleman/Luxaire and Nortek

Covers: US residential split AC, heat pumps, furnaces and air handlers sold under about 40 badges by seven manufacturer families, current to 2026 (including Johnson Controls' residential business moving to Bosch in 2025).

Cross-checkedBrands: Carrier, Bryant, Payne, Day & Night, Heil, Tempstar, Comfortmaker, Arcoaire, KeepRite, Airquest, Goodman, Amana, Daikin, Janitrol, Rheem, Ruud, WeatherKing, Sure Comfort, Trane, American Standard, Ameristar, RunTru, Oxbox, Lennox, Armstrong Air, AirEase, Ducane, Concord, MagicPak, York, Coleman, Luxaire, Guardian, Champion, Evcon, Fraser-Johnston, Frigidaire, Maytag, Gibson, Westinghouse, Tappan, Intertherm, Miller2 components

Residential HVAC is a handful of factories behind many badges. Once you know the family, you know the board, flash codes, serial date format and parts channel. Families: Carrier (Carrier, Bryant, Payne + ICP's Heil, Tempstar, Comfortmaker, Arcoaire, KeepRite, Airquest, Day & Night); Daikin Comfort (Goodman, Amana HVAC, Daikin, older Janitrol); Rheem (Rheem, Ruud, WeatherKing, Sure Comfort); Trane Technologies (Trane, American Standard, Ameristar, RunTru, Oxbox); Lennox (Lennox + Allied Air: Armstrong Air, AirEase, Ducane, Concord, MagicPak); York, now Bosch (York, Coleman, Luxaire, Guardian, Champion, Evcon, Fraser-Johnston); Nortek Global HVAC (licensed Frigidaire, Maytag, Gibson, Westinghouse, Tappan; own Intertherm, Miller).

Safety first

  • Kill power at the disconnect before opening electrical covers; capacitors can hold a charge.
  • Refrigerant circuit work is blocked (EPA 608): diagnose and refer.
  • Gas valve, burner and venting work is blocked: diagnose and refer.

How it works

Sister badges usually share the chassis, board and compressor family but use different model prefixes and warranties. Never assume parts identity across badges; confirm with the exact model.

Rheem family: first model letter R = Rheem, U = Ruud, W = WeatherKing on the same unit (older RAKA/UAKA/WAKA condensers differed only by stickers).

Goodman family: first letter G = Goodman, A = Amana (HVAC Amana is a Daikin/Goodman brand, unrelated to Amana appliances).

ICP: one model scheme across its badges; the first letters mark tier/badge (an entry line uses N across several badges, e.g. N4A-style condensers), so a Heil-style string decodes the same on Tempstar, Comfortmaker or Day & Night.

Serial date formats differ by family and help confirm it: Carrier/Bryant = 4 digits + plant letter + 5 digits (week, year); Goodman/Amana = 10 digits starting YYMM; Rheem/Ruud HVAC = letter + week-year; Trane/American Standard 2010+ = YYWW; Lennox = plant, year, month letter. (Rules in brands.json.)

Ownership changes to know: ICP joined Carrier in 1999; Goodman bought Amana HVAC with Raytheon Appliances in 1997 and Daikin bought Goodman in 2012 (renamed Daikin Comfort Technologies North America in 2022); Johnson Controls sold its residential and light-commercial HVAC (York and sister brands) to Bosch, closing July/August 2025.

Westinghouse is split: its HVAC business went to Borg-Warner/York in 1981 (with Luxaire and Fraser-Johnston names), while the Westinghouse HVAC name is now used under license by Nortek.

Components & tests

Unlock all 2 components, specs, service mode and teardown

Full library + AI assistant + the OnCall Tech app for iPhone & Android. $34.90, one time.

Get lifetime access

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): Air-source heat pump outdoor unit beside a house in the snow by PeterEastern, CC BY-SA 4.0

Diagnostic guides for this appliance

Guide · Fundamentals

Blower runs nonstop and no cooling on a new HVAC system: A2L refrigerant leak sensor

A2L systems carry a refrigerant leak sensor near the indoor coil. When it reports a leak, or when the sensor fails or loses communication, the control stops the compressor and runs the blower to dilute any refrigerant. This guide separates a sensor or wiring fault from a possible real leak; any real leak is referred to an EPA 608 technician.

8 steps ~40 minmoderate
Guide · Fundamentals

Confirming an inverter board's DC bus is discharged before you touch it

Inverter boards store high-voltage DC in large capacitors after the power is off, and a dark LED does not mean the board is safe. Remove power, wait the maker's time, then measure the DC bus at the marked test points until it reads 0 V. Only then unplug loads or handle the board.

7 steps ~20 minmoderate
Guide · Fundamentals

Load will not turn off: shorted triac or welded relay (board vs load)

When a load runs with no command, the board output that feeds it is usually shorted: triacs most often fail shorted and relay contacts can weld closed after inrush. Confirm the output is truly on with the load connected (not a ghost reading), then test the load itself, because a shorted or seized load is what usually kills the output.

8 steps ~40 minmoderate

Other tech fundamentals manuals

Manual · Fundamentals

ECM blower motors in depth: constant-torque vs constant-airflow, connectors and safe checks

Electronically commutated (ECM) blower motors in residential furnaces, air handlers, fan coils and package units: constant-torque tap motors (X13-style and similar) and programmed constant-airflow / variable-speed motors (ECM 2.3, 2.5, 3.0 and similar families). Concepts and safe checks only; the equipment's own wiring diagram and the motor maker's guide always win.

8 components6 common failuresAll
Manual · Fundamentals

Inverter drives in appliances: rectifier, DC bus and output stage, safe checks and when to refer

Variable-speed (inverter) drives in refrigerators, freezers, mini-splits and inverter window/portable ACs, plus the similar drives in direct-drive washers and BLDC pumps. Electrical concepts and safe checks only. Anything that opens the sealed refrigerant system is blocked (EPA 608).

8 components6 common failuresAll
Manual · Fundamentals

Control board output devices: relays, triacs and transistor drivers, and how loads kill them

Output switching parts on appliance control boards (washers, dryers, dishwashers, refrigerators, ranges, microwaves): electromechanical relays, triacs with their snubbers and opto-isolators, and transistor/MOSFET drivers for DC loads. Explains failure patterns and what to measure; no board-level repair.

8 components5 common failuresAll
HVAC brand families: who builds Carrier/Bryant/Payne/ICP, Goodman/Amana/Daikin, Rheem/Ruud, Trane/American Standard, Lennox/Allied, York/Coleman/Luxaire and Nortek · OnCall Tech