York
Part of Bosch Home Comfort since 2025 (formerly Johnson Controls). Affinity and LX residential lines share platforms with Coleman, Luxaire, Champion and Fraser-Johnston — one parts book, several stickers. York applied and commercial equipment (chillers, applied rooftops) remains with Johnson Controls.
The family: Bosch’s own inverter lines plus York, Coleman, Luxaire and Champion — the residential HVAC brands acquired from Johnson Controls in 2025.
Same family: Bosch, Coleman, Luxaire, Champion
What they make
Split system A/C (straight cool)
Covered in the simulatorOutdoor condenser plus an indoor furnace-and-coil or air handler — the most common machine in single-family homes and garden-style multi-family.
The whole sim is built on this machine: every wing of the board and the guided no-cool flow apply directly.
Start a guided call →Practice: whole system dead →Practice: outdoor unit dead →Practice: runs but won’t cool →Practice: no air inside →Practice: acting possessed →Practice: blows fuses →Practice: gauges on →Practice: wrong part, wrong size →A2L start-up guide →
Heat pump (split)
Lessons carry overA split system that also heats: one reversing valve decides which coil condenses. Everything a straight-cool split has, plus the O (or, on some brands, B) circuit and defrost.
The HEAT PUMP wing of the board works the reversing valve; the guided flow routes heat pumps to escalation until its playbook ships. The electrical side transfers one-for-one.
Open in the Copilot (reference) →Practice: heat pump →Practice: whole system dead →Practice: outdoor unit dead →Practice: runs but won’t cool →Practice: no air inside →Practice: acting possessed →Practice: blows fuses →Practice: gauges on →Practice: wrong part, wrong size →A2L start-up guide →
Gas furnace
Covered in the simulatorThe indoor half of most split systems outside the Sun Belt: burners and heat exchanger below, the A-coil above, the 24V control system inside.
The control side — door switch, transformer, board, blower, low-voltage fuse — is fully modeled as the sim’s indoor cabinet, and the guided flow applies on cooling complaints. Combustion-side diagnostics are on the roadmap.
Start a guided call →Practice: whole system dead →Practice: no air inside →Practice: acting possessed →Practice: blows fuses →
Air handler / fan coil
Covered in the simulatorThe all-electric indoor cabinet: blower, coil, and controls. In multi-family it hides in closets and mechanical rooms; hydronic fan-coil versions swap the coil’s refrigerant for water.
Modeled as the sim’s indoor unit: control power, blower circuits, condensate float, coil airflow. Hydronic (water-coil) versions add loop diagnosis the sim doesn’t model yet.
Start a guided call →Practice: whole system dead →Practice: no air inside →Practice: runs but won’t cool →Practice: acting possessed →Practice: blows fuses →Practice: gauges on →A2L start-up guide →
Evaporator coil
Covered in the simulatorThe indoor coil itself — cased or uncased, A, N or slab — often replaced separately from everything else, which is where mismatches are born.
Freeze-ups, restrictions, airflow starvation and mismatched-coil audits are all on the board, and the guided flow’s superheat/subcooling paths read straight through it. Match by capacity and metering device, never by badge.
Start a guided call →Practice: gauges on →Practice: runs but won’t cool →Practice: wrong part, wrong size →A2L start-up guide →
Package unit
Lessons carry overThe whole system in one outdoor cabinet — on a pad beside the house or on the roof. Gas/electric, straight cool, or heat pump.
Same parts, one cabinet: contactors, dual-run caps, PSC/ECM motors and the refrigerant circuit fail exactly like the board’s scenarios. The guided flow’s split-system routing doesn’t fit a single cabinet, so it escalates package units by design.
Open in the Copilot (reference) →Practice: runs but won’t cool →Practice: blows fuses →Practice: gauges on →
Ductless mini split
Reference for nowInverter-driven outdoor unit feeding one or more wall, ceiling or compact-ducted heads over a communicating line. The fastest-growing machine in both segments.
Inverter boards, communicating controls and electronic expansion valves — not the contactor-and-run-cap machine the board models, and dedicated mini-split tickets are on the roadmap. From the A2L start-up guide, the refrigerant handling, nitrogen and deep-vacuum discipline transfer; its charge-to-subcooling step does not — these machines charge by weight to the manufacturer’s line-length math, behind flares torqued to spec. On the call itself, flash codes and the manufacturer’s service data lead.
Tech support
Tech support here is the guided Copilot with your York info already loaded — one question at a time, evidence before parts, and everything you enter rides into the service report.
Opens the guided Copilot with York already on the equipment card.
Reading York model numbers
Letter block, then size: YCJF36S41S1 reads Y (York) / CJ family / F efficiency / 36 = 3 tons. Coleman and Luxaire wear TC/AC-style prefixes on the same platforms. Furnaces TG9S/TM9V code heating input in the digits after the letters. (Bosch IDS inverter models use their own BOVA/IDS grammar — size still rides in the digits: BOVA-36 is 3 tons.)
YCJF36S41S1— York LX split A/C, 14–16 SEER class (the D tier is the 13 SEER version), 3 tons (36).TCGD48S41S3— Coleman/Luxaire-family split A/C, 4 tons (48).
Thirty years of these units
1990s–2000s: York H*/E* R-22 lines. 2010s: YCJ/YCG R-410A families under Johnson Controls. Since 2025 the badges live at Bosch Home Comfort — platforms and grammar carried over.
Residential packages (PCE/PCG-style) carry the same trailing size codes.
Dating a unit from the serial
Post-October-2004: plant letter, then the year’s two digits split around a MONTH letter — the letter is the month, not a year code. Older serials letter-code the year on a repeating cycle; date those from the family table. (Bosch IDS serials are their own scheme entirely.) Serial W1E5xxxxxxx → E = May, 1_5 = 2015: May 2015.
Common rule — spot-check against the manufacturer’s table
Need the wiring? The practice board’s ladder diagram is live and interactive — the same circuit these units share, with a meter on it. Open the board →