General Assist Technical Reference
S-Series VRF System
Legacy R407C system overview and indoor-unit lineup
Practical operating era: approximately early 2000s to around 2010
The AIRSTAGE S-Series was one of Fujitsu General's early Variable Refrigerant Flow systems. It was designed for small-to-medium commercial buildings and multi-zone applications requiring individual room control, quiet operation and flexible indoor-unit selection.
Legacy product: The S-Series is no longer a current product platform. Always confirm the complete model and serial number before ordering parts, selecting manuals, diagnosing controls or proposing replacement equipment.
1. System overview
| Feature | Typical S-Series reference |
|---|---|
| System type | Heat-pump Variable Refrigerant Flow system |
| Refrigerant | R407C zeotropic blend |
| Compressor technology | Inverter-driven compressor, model dependent |
| Connectable indoor units | Up to 16, depending on the outdoor model and approved combination |
| Indoor-unit range | 10 product types and 45 models, from approximately 2.2 kW to 17.0 kW |
| Typical applications | Offices, hotels, schools, retail premises and other multi-zone buildings |
| Control options | Wired and centralised control options, subject to model compatibility |
| Approximate era | Approximately 2001-2010, with market and stock overlap |
Key operating characteristics
| 1 | Variable-capacity control. The inverter system adjusts compressor output to match the combined demand of operating indoor units. |
| 2 | Individual zone control. Connected indoor units can be controlled separately, subject to system operating mode and controller configuration. |
| 3 | Flexible indoor selection. The range included cassette, ducted, floor/ceiling, wall-mounted and ceiling-wall indoor-unit styles. |
| 4 | R407C service requirements. Refrigerant must be handled as a blend and charged in liquid form by weight. |
2. Indoor-unit lineup
The supplied S-Series range sheet identifies 10 indoor-unit types and 45 models, covering nominal capacity classes from approximately 2.2 kW to 17.0 kW.
| Indoor-unit type | Models shown | Capacity coverage shown |
|---|---|---|
| Compact cassette | AUXB07LATF, AUXB09LATF, AUXB12LATF, AUXB14LATF, AUXB18LATF | 2.2-5.3 kW |
| Cassette | AU*A20LATF, AU*A25LATF, AU*A30LATF, AU*A36LATF, AU*A45LATF, AU*A54LATF | 5.7-14.1 kW |
| Compact duct | ARXB07LALF, ARXB09LALF, ARXB12LALF, ARXB14LALF, ARXB18LALF | 2.2-5.3 kW |
| Low-static pressure duct | ARXB25LATF, ARXB30LATF, ARXB36LATF, ARXB45LATF | 7.1-12.7 kW |
| Duct | ARXA25LATF, ARXA30LATF, ARXA36LATF, ARXA45LATF | 7.1-12.7 kW |
| High-static pressure duct | ARXC36LATF, ARXC45LATF, ARXC60LATF | 10.5-17.0 kW |
| Floor / ceiling | AB*A12LATF, AB*A14LATF, AB*A18LATF, AB*A24LATF | 3.6-6.8 kW |
| Ceiling | AB*A30LATF, AB*A36LATF, AB*A45LATF, AB*A54LATF | 8.8-14.1 kW |
| Wall mounted | AS*A18LATF, AS*A24LATF, AS*A30LATF | 5.3-8.8 kW |
| Ceiling wall | AW*A07LATF, AW*A09LATF, AW*A12LATF, AW*A14LATF, AW*A18LATF, AW*A24LATF, AW*A30LATF | 2.2-8.8 kW |
Model-table notation: An asterisk shown in the historical range sheet represents a model-family character variation. Confirm the complete rating-label model rather than searching or ordering from the abbreviated family notation.
3. R407C service and maintenance notes
| Service item | Required approach |
|---|---|
| Charging method | Charge R407C in liquid form by weight to preserve blend composition. |
| Temperature glide | Use the correct bubble and dew temperature references when evaluating superheat, subcooling and saturation temperatures. |
| Loss of charge | Where a significant leak or fractionation is suspected, recover the remaining charge, repair the leak, evacuate and recharge the specified mass. |
| Oil and contamination | Use the specified oil and keep the refrigeration circuit dry and clean. Do not mix refrigerants or oils. |
| Parts availability | Availability is model and production dependent. Confirm the exact part number and current stock status before committing to a repair. |
| Documentation | Use the exact model-specific service manual, wiring diagram and controller documentation. |
Do not top up blindly: R407C is a blended refrigerant. An unknown or significantly depleted charge should not be corrected solely from operating pressure.
Information required for technical support
| Check | Done |
|---|---|
| Complete outdoor model and serial number | ☐ |
| All connected indoor model numbers | ☐ |
| Controller type and displayed fault code | ☐ |
| Outdoor PCB LED indication | ☐ |
| Operating pressures and pipe temperatures | ☐ |
| Refrigerant history, leak repairs and charge mass | ☐ |
| Photos of rating labels, PCBs and wiring | ☐ |
4. Repair versus replacement planning
| Consider repair where | Consider replacement planning where |
|---|---|
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Modernisation options: A current replacement must be selected through a new heat-load, piping and controls assessment. Do not assume that an existing S-Series indoor network can be directly connected to a newer J-Series, V-Series or R32 platform.
Customer communication: The age of the product does not automatically require replacement. Present the customer with the confirmed fault, parts availability, repair risk, expected remaining life and replacement implications before making a recommendation.
This article is a practical legacy-system reference based on the supplied S-Series indoor-unit range sheet. It does not replace the applicable model-specific installation, service, design or controller manuals. Historical model availability and production timing varied by market.