Mitsubishi Mr Slim Aircond (MS-A10VD) Malfunction
Symptoms:
- Indoor unit doesn't receive the signal from remote controller, the aircond is not turn on.
- When the "Emergency Operation" switch is pressed, indoor unit operates.
Analysis:
- Change new battery for remote controller. This is to make sure the battery is in good condition.
- Put the remote controller in front of smartphone's camera, you should be able to see the IR LED is flashing purple or white light on your phone's screen. This confirms the remote is transmitting a signal, even if invisible to the naked eye.
- Open up the indoor unit cover, look for manual switch. When the "Emergency Operation" switch is pressed, indoor unit operates. It means most likely the IR Receiver Board is malfunction. This is executed when the remote controller is lost, broken, or has dead batteries.
- Operation Sequence (Common):
- First Press: Starts a 30-minute test run (usually high fan speed, no temperature control).
- After 30 Mins: Often shifts to a default COOL mode (approx. 25°C).
- Subsequent Presses: Cycles between EMERGENCY COOL and STOP modes.
- If repairing the receiver on the PCB board, look for 38kHz, standard 940nm 5mm IR Receiver Module (VS1838 / VS1838B / TSOP4838).
- TSOP4838: Manufactured by Vishay, a major brand in electronics components. It is more expensive, roughly US$1.
- VS1838 / VS1838B / HX1838: A generic or third-party manufactured component, frequently sold in hobbyist kits. It is significantly cheaper, sometimes just 14 - 20 cents.
- After bought and received the TSOP4838 (07/Mar/2026), found out that the Receiver Board was designed using different pinout configuration, it is using pinout configuration for TSOP2238.
- The Vishay TSOP2238 and TSOP4838 are both 38kHz infrared (IR) receiver modules that are nearly identical in technical performance and electrical specifications. The primary difference between them is the internal pin assignment, which determines how they are wired to a power source and ground.
- Pin Assignment Differences
- While both modules use a 3-pin configuration, their layout differs, making them incompatible if swapped in a circuit without adjusting the wiring. According to the manufacturer, Vishay, the pinning is as follows:
- TSOP2238 Pinout: 1 = OUT, 2 = (Supply), 3 = GND (Ground).
- TSOP4838 Pinout: 1 = OUT, 2 = GND (Ground), 3 = (Supply).
- Both use AGC2, which is optimized for legacy designs and all common IR remote control data formats.
- For new projects, manufacturers often recommend switching to the TSOP2438 (compatible with TSOP2238 pinout) or TSOP4438 (compatible with TSOP4838 pinout). These newer series feature AGC4, which provides better immunity against modern interference sources like Wi-Fi and energy-saving fluorescent lamps (CFLs).
- Key Differences at a Glance:
- Recommended Parts Listing (Legacy: AGC2 vs New: AGC4)
Photos:
- Instruction of Troubleshooting (from Service Manual)
- Emergency Operation Switch location
- Troubleshooting Flow (from Service Manual)
- Mr Slim (MS-A10VD) Indoor Unit PCB & Receiver PCB Diagram
- IR Receiver Module (VS1838 / VS1838B) inside Receiver PCB
- Model: DH00L515
- Replacement Part Number: E22 41G 329
- Remove the screw caps of the panel. Then, remove the screws.
- Open the holder, dismantle the Receiver Board from indoor unit
- Simple IR Remote Tester (with battery)
Video:
- Testing the old IR Receiver Module with Smartphone (Remote Control): TBA
[ Pending to dismantle from Mitsubishi Aircond ]
= To Be Update Later =
- Testing the new TSOP4838 with Smartphone (Remote Control): OK
Costs Involved:
- IR Receiver Module (TSOP4838): US$1.00 (bought from Element14)
- IR Receiver Module (TSOP2238): US$1.25 (bought from Element14)
Tools Required:
- Received IR Receiver Module (TSOP4838) on 05/Mar/2026.
- Dismantled Receiver Board of Mitsubishi Aircond. Soldered TSOP4838 and found out pin configuration was wrong.
- TSOP4838 is not suitable for this aircond. The aircond unable to turn ON due to incorrect part soldered on board.
- Need to source for alternative IR Receiver (TSOP2238)
Location of Receiver Board
Dismantled Receiver Board
from its Holder
TSOP4838 & Original IR Receiver Module
Soldered TSOP4838 on Receiver Board
(but aircond not working)
Pin Configuration on Board
(1: Out, 2: Vs, 3: Gnd)
