First-Generation FR-S/BRZ/86 Integrated Under-Dash HVAC Unit and Case Identification

Checked formal service replacement chains are SU003-01999 -> SU003-07633 for the Toyota/Scion without-automatic-A/C complete unit, 72100CA050 -> 72100CA051 for the Subaru Base/manual-HVAC complete unit and 72100CA070 -> 72100CA071 for the Subaru High/automatic-climate complete unit. SU003-02001 and SU003-07635 are retained as separate checked automatic-climate catalog/production branches; no formal relationship between them is asserted. Case halves, blower cases, heater cores, evaporators and expansion valves are separately serviced components rather than complete-unit supersessions. No Toyota/Scion-to-Subaru supersession or whole-unit interchange is claimed.

Treat the factory assembly as one integrated under-dash HVAC unit, not three universally separable donor modules. Begin with both VINs/build dates, badge and installed controls; distinguish manual HVAC from automatic dual-zone climate, then match the exact service identity and molded/printed case references. Compare firewall heater tubes, evaporator/expansion-valve connections, condensate drain, duct joints, mounting tabs, blower opening and controller interface, temperature/mode/recirculation doors, actuators, sensors, harnesses, seals and hardware. Seller words complete heater box are not an inventory: require written confirmation of heater core, evaporator, expansion valve, blower motor/fan, manual resistor or automatic controller, doors/actuators, sensors, drain tube, ducts, harnesses, brackets and fasteners. Reject cracked or warped cases, broken tabs, seized doors, kinked or cut tubes, coolant or refrigerant-oil residue, corrosion, fire/flood exposure, mold, rodents, heavy debris, odor, cut wiring or unknown coating/disinfectant. Pressure-test or otherwise verify cores before major dash labor. Recover refrigerant with approved equipment before opening a circuit likely to discharge it; work only on a cold and depressurized cooling system. Use current Toyota/Subaru procedures and qualified dash/HVAC service. Preserve ZN6-0041 external A/C ownership and ZN6-0045 blower-electrical diagnosis ownership.

Direct-replacement heater cores, evaporators and expansion valves are component-level alternatives only after the exact badge/VIN, climate branch, dimensions and interfaces are verified; a core or valve listing is not a complete under-dash unit and does not prove case interchange. A clean exact-service-identity factory donor rebuilt with independently verified cores and new required seals can be considered only with actual-piece photographs, written contents, contamination history, test method, warranty and return terms. Universal systems, mixed manual/automatic control conversions and unsupported cross-badge whole-case swaps alter controls, ducts, drains, wiring, coolant/refrigerant interfaces and major dash work and are outside this guide.

US/LHD first-generation factory integrated under-dash HVAC unit only. Match both VINs/builds, badge, installed manual versus automatic climate controls, exact unit/case identity, interfaces and written contents. Toyota/Scion and Subaru numbers are parallel badge anchors, not proof of cross-brand whole-case interchange. Reject cracked, contaminated, mold/rodent/flood/fire-exposed or cut-wiring donors. Core-only listings are not complete units. Require lawful refrigerant recovery, a cold/depressurized cooling system and qualified dash/HVAC service; seller states are dated.

Supersede reviewed 13 unique research sources for this guide. 5 also appear above as a seller or official action and are not repeated here; 8 additional citations follow.

Research last verified 2026-08-06.

1. Toyotapartsdeal — heating air conditioning cooler unitOpen source
2. Toyotapartsdeal — heating air conditioning cooler unitOpen source
3. Subaru Parts Deal — heater systemOpen source
4. Subaru Parts Deal — heater systemOpen source
5. Toyotapartsnow — a c evaporator heater componentsOpen source
6. Techinfo subaru — MSA5B1606ABRZQRG111115Open source
7. NHTSA — MC 10117546 9999Open source
8. EPA — regulatory requirements mvac system servicingOpen source