Daikin LV Series wall-mount mini-splits (FTXS09-36LVJU indoor, RXS / RKS LVJU outdoor): quick sheet

Covers: Daikin inverter pair wall units FTXS09LVJU, FTXS12LVJU, FTXS15LVJU, FTXS18LVJU, FTXS24LVJU, FTXS30LVJU, FTXS36LVJU with RXS..LVJU heat pump outdoor units (RKS30/36LVJU cooling only), plus FDXS09/12LVJU slim ducted units, covered by Daikin service manual SiUS091133. The digits are the nominal capacity in kBtu/h. The newer 19 Series (FTX..NMVJU) and Oterra (FTXF) are different platforms; see the Daikin 19 Series sheet.

Single sourceBrands: Daikin5 components

Self-diagnosis codes are shown on the wireless remote (ARC452 series) after a service check, not on the unit. The indoor unit has DC fan motors on FTXS (AC motor on FDXS). Many codes split into System (U-codes), Indoor (A and C codes) and Outdoor (E, F, H, J, L, P codes).

Safety first

Outdoor inverter capacitors hold charge after power off.
No refrigerant work: refer to an EPA 608 certified technician.

How it works

Codes appear only when the system has shut down on a fault.

Service check method 1: point the remote at the unit and hold TIMER CANCEL 5 seconds ('00' appears); press TIMER CANCEL repeatedly, stepping through codes, until the unit gives a long beep: the code then shown is the fault.

Method 2 (if method 1 doesn't find it): press TEMP up, TEMP down and MODE together to enter diagnosis, then change each digit until a long beep.

To exit, hold TIMER CANCEL 5 seconds or leave the remote idle 60 seconds.

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): 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 · 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, on GE Zoneline (2019 technical service guide) you hold FAN and the red AUX button together while the unit is OFF, and AUX clears stored faults; other models use other sequences, so use the model's tech sheet). Read the active code, fix the cause, then clear it.

4 steps ~20 mineasy

Other air conditioners manuals

Manual · Air Conditioner

Carrier Infinity Greenspeed 24VNA6 air conditioner and 25VNA4 heat pump (variable speed): quick sheet

Carrier Infinity Greenspeed Intelligence variable-speed outdoor units: 24VNA6 air conditioner (up to 26 SEER) and 25VNA4 heat pump (up to 24 SEER, up to 13 HSPF), 2-5 ton. Nomenclature from the service manual: 24 = AC, 25 = HP; V = variable speed; N = Infinity series; A = Puron (R-410A); 6 / 4 = SEER tier; two digits = nominal capacity (e.g. 36 = 36,000 BTU/h); voltage digit 3 = 208/230-1; compressor ID 4 = variable-speed scroll, 5 = variable-speed rotary. Serial format: week + year + plant letter + sequence (e.g. 0118E00001). Other 24VNA families (24VNA0, 24VNA9) use different software and code lists.

5 components4 common failuresCarrier

Manual · Air Conditioner

Trane XV20i / XV18 variable-speed outdoor units (4TTV0 AC, 4TWV0 heat pump, ComfortLink II): quick sheet

Trane variable-speed TruComfort / ComfortLink II communicating outdoor units: 4TTV0 air conditioners (XV20i family, e.g. 4TTV0024A1000C, 4TTV0036, 4TTV0048, 4TTV0060, 4TTV0061) and 4TWV0 heat pumps (Service Facts 4T-V0-SF). They use an Integrated Variable Speed Control (IVSC) board and a Communicating Display Assembly (CDA) in the outdoor unit. Distributor listings note several 4TTV0 revisions; confirm the full model on the nameplate before ordering parts. Single-stage XR14/XR16 units are on a separate sheet.

4 components3 common failuresTrane

Manual · Air Conditioner

Lennox XC21 air conditioner and XP21 heat pump (Dave Lennox Signature, iComfort-enabled): quick sheet

Lennox XC21 (air conditioner, service literature Corp. 1007-L2) and XP21 (heat pump, Corp. 1031-L7), 2, 3, 4 and 5 ton, R-410A, expansion valve indoor coils only. Both use an A175 main control (outdoor control part number 101798-xx) that works in communicating (iComfort) or conventional 24 V mode, plus a separate fan motor control. The XP21 literature describes a two-stage scroll compressor; the 2018 XC21 literature describes the compressor as one-stage while the same control section covers two-stage units, so confirm staging on the nameplate. For ML14XC1/EL16XC1 single-stage units see the separate sheet.

4 components3 common failuresLennox