mypros+
Error code reference

Samsung Air Conditioner Error Code E172

Change of EVAP IN temperature of other indoor unit during piping check.

Samsung codesSamsung air conditioner codes

Change of EVAP IN temperature of other indoor unit during piping check.

First step from the service manual

Check indoor unit address matches MCU; check EEV connection; verify piping connections.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

MyPros+ Max

Get the full diagnostic procedure for E172.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What E172 means on a Samsung air conditioner

Error code E172 on a Samsung air conditioner occurs during the piping check phase of a multi-split or VRF system installation or commissioning. During a piping check, the system runs through a controlled sequence to verify that refrigerant is flowing correctly through each indoor unit circuit. The error triggers when the evaporator inlet (EVAP IN) temperature of a different indoor unit, other than the one being actively checked, changes unexpectedly during this process. This indicates that refrigerant is leaking into or affecting a circuit it should not be influencing at that moment, pointing to a cross-piped or incorrectly routed refrigerant circuit.

The most likely root causes involve a mismatch between indoor unit address settings and the MCU (master control unit) configuration, incorrect piping connections between the indoor units and the outdoor unit, or a faulty or improperly wired EEV (electronic expansion valve). The EEV controls refrigerant flow into each indoor unit's evaporator coil. If the EEV on a particular unit is stuck open, miswired, or receiving incorrect signals, refrigerant may flow to the wrong circuit during the piping check, causing the EVAP IN sensor on an unintended indoor unit to register a temperature shift.

Diagnosing E172 requires verifying that each indoor unit's address is correctly programmed and matches the MCU's expected configuration. Technicians should also inspect all piping connections to confirm they correspond to the correct indoor unit branch circuits. The EEV connector and harness on each unit should be checked for secure seating and continuity. If the wiring and addressing check out, refrigerant circuit tracing may be necessary to confirm correct piping routing.

Source: manufacturer service documentation.

Common causes of E172

  1. 01

    Incorrect indoor unit address configuration

    Wiring / connection

    If an indoor unit's address does not match what the MCU expects, the system cannot properly track which unit is being tested during the piping check, causing EVAP IN temperature changes to be attributed incorrectly. Verify that each indoor unit address is set correctly according to the system's wiring diagram.

  2. 02

    Cross-piped or misrouted refrigerant connections

    Wiring / connection

    If refrigerant piping between the outdoor unit and indoor units has been connected to the wrong branch ports, refrigerant will flow into unintended indoor unit coils during the piping check, triggering E172. Trace all piping connections and confirm they match the designed circuit layout.

  3. 03

    Faulty or stuck-open EEV

    Part replacement

    An electronic expansion valve that is stuck in the open position or not responding to control signals will allow refrigerant to flow into a coil when it should be blocked. Inspect the EEV connector for secure seating and check the valve for proper operation.

  4. 04

    EEV wiring harness issue

    Wiring / connection

    A loose, damaged, or incorrectly routed EEV connector can cause the valve to receive wrong signals or fail to close properly during the piping check sequence. Inspect the harness and connector pins for damage, corrosion, or incorrect installation.

  5. 05

    EVAP IN temperature sensor fault on an indoor unit

    Part replacement

    If the evaporator inlet temperature sensor on one of the indoor units is reading inaccurate values, the system may falsely detect a temperature change during the piping check. Check the sensor resistance values against specifications and replace the sensor if readings are out of range.

See the test procedure for each cause

Frequently asked questions about E172

What does E172 mean on a Samsung air conditioner?
E172 indicates that during the system's piping check sequence, the evaporator inlet temperature of an indoor unit that was not being actively tested changed unexpectedly. This suggests refrigerant is flowing into the wrong circuit, which typically points to incorrect piping connections, mismatched indoor unit address settings, or an EEV that is not controlling refrigerant flow correctly. The error is most common during initial installation or after system modifications.
Can I fix E172 myself, or do I need a technician?
Resolving E172 generally requires someone with HVAC technical knowledge and access to the system's wiring diagrams and configuration settings. Checking indoor unit address settings is something an informed installer can do, but tracing refrigerant piping, inspecting EEV wiring, and running a piping check sequence safely requires proper tools and training. Homeowners should contact a certified HVAC technician to diagnose and correct this error.
Is it safe to run my Samsung air conditioner while E172 is displayed?
E172 occurs during the piping check commissioning phase and indicates a refrigerant circuit issue that has not been resolved during setup. Running the system in this state risks improper cooling performance and potential refrigerant circuit stress. It is best to avoid operating the system until the piping configuration and addressing have been verified and corrected by a qualified technician.
Will resetting the unit clear the E172 error?
A simple reset will not permanently clear E172 because the error is tied to the results of the piping check sequence, not a temporary communication glitch. The system will repeat the piping check upon restart and will generate the error again if the underlying issue, such as incorrect piping or address settings, has not been corrected. The root cause must be resolved before the piping check can complete successfully and the error will clear.
How much does it cost to repair an E172 error on a Samsung multi-split system?
Repair costs depend on what is causing the error. If the fix involves only reprogramming indoor unit addresses or reseating an EEV connector, labor costs might range from $75 to $200. If piping must be rerouted or an EEV needs replacement, costs can range from $200 to $600 or more depending on system complexity, refrigerant handling requirements, and local labor rates. Getting a diagnostic visit from a certified HVAC technician is the best way to get an accurate estimate.

Related Samsung air conditioner codes

All Samsung air conditioner codes
View all 572 Samsung air conditioner codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass