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Error code reference

Samsung Air Conditioner Error Code 407

Compressor down by high pressure sensor protection control

Samsung codesSamsung air conditioner codes

Compressor down by high pressure sensor protection control - detects when high pressure sensor value over 4.0MPa (or 38kg/cm2).

First step from the service manual

Check if service valve is open; compare manifold gauge and S-net values; check if indoor/outdoor EEV operates; check for piping clogs; check fan operation; check refrigerant amount.

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

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What 407 means on a Samsung air conditioner

Samsung error code 407 indicates the compressor has been shut down by the high pressure protection control circuit. This safety function activates when the high pressure sensor detects refrigerant pressure at or above 4.0 MPa (approximately 38 kg/cm2) on the high side of the refrigeration circuit. At these pressures, continued compressor operation risks damaging the compressor, refrigerant lines, and connected components. The system halts compressor operation automatically to prevent catastrophic failure.

The high pressure sensor monitors the discharge side of the compressor continuously during operation. When pressure climbs to the protection threshold, the control board triggers the shutdown and logs code 407. Common root causes include a closed or partially closed service valve restricting refrigerant flow, a blocked or restricted liquid line or filter drier, a malfunctioning outdoor electronic expansion valve (EEV) that fails to open properly, outdoor fan failure reducing condenser heat rejection, or an overcharge of refrigerant in the system. Any of these conditions can cause discharge pressure to spike beyond safe limits.

Diagnosis should begin by confirming the service valve is fully open, then connecting manifold gauges to compare actual system pressures against the values reported through S-net diagnostics. Technicians should verify that both indoor and outdoor EEVs are operating and responding to commands. Inspect refrigerant piping for kinks or blockages, confirm outdoor fan motor and blade are functioning normally, and verify refrigerant charge is within specification. If pressures remain elevated after ruling out mechanical restrictions and fan issues, refrigerant overcharge is a strong possibility.

Source: manufacturer service documentation.

Common causes of 407

  1. 01

    Closed or partially closed service valve

    Wiring / connection

    If a service valve on the outdoor unit was left closed or not fully opened after installation or maintenance, refrigerant flow is restricted and discharge pressure rises quickly. Check that all service valves are fully back-seated open.

  2. 02

    Outdoor fan failure or reduced airflow

    Part replacement

    If the outdoor condenser fan motor has failed or the fan blade is obstructed, heat cannot be rejected from the coil efficiently and high-side pressure climbs. Confirm the fan spins freely, at correct speed, and without obstruction.

  3. 03

    Malfunctioning outdoor or indoor EEV

    Part replacement

    An electronic expansion valve that is stuck closed or not responding to control signals will restrict refrigerant flow and cause high pressure on the discharge side. Use S-net diagnostics or direct commands to verify EEV operation and step response.

  4. 04

    Refrigerant piping restriction or blockage

    Part replacement

    A kinked line, clogged filter drier, or debris blockage in the liquid line can back up refrigerant and raise high-side pressure significantly. Compare manifold gauge readings at multiple points to isolate the restriction location.

  5. 05

    Refrigerant overcharge

    Wiring / connection

    Excess refrigerant in the system raises both high-side pressure and condensing temperature. If all mechanical components check out normally, compare actual subcooling values against specification to determine whether refrigerant needs to be recovered.

See the test procedure for each cause

Frequently asked questions about 407

What does 407 mean on a Samsung air conditioner?
Error code 407 means the system detected high-side refrigerant pressure at or above 4.0 MPa (38 kg/cm2) and shut down the compressor as a safety precaution. This protection function prevents damage to the compressor and refrigerant circuit. The fault will remain active until the cause of elevated pressure is identified and corrected by a qualified technician.
Can I fix error code 407 myself?
Some initial checks are accessible to a knowledgeable DIYer, such as confirming the outdoor fan is running, checking for physical obstructions at the outdoor unit, and verifying service valves are fully open. However, diagnosing EEV operation, measuring system pressures with manifold gauges, and correcting refrigerant charge all require EPA Section 608 certification and specialized tools. Most of the root causes for code 407 require a licensed HVAC technician to resolve safely.
Is it safe to keep using my air conditioner when it shows error 407?
No. Error 407 means the system has already shut down the compressor to prevent damage from excessive pressure. Attempting to bypass the fault or repeatedly resetting the unit without addressing the root cause risks compressor failure, refrigerant line rupture, or damage to other system components. Leave the unit off until a technician has diagnosed and repaired the problem.
Will resetting the unit clear error code 407?
A power reset may temporarily clear the fault and allow the system to restart, but if the underlying cause of high pressure has not been corrected the unit will trip the same protection and log code 407 again, often within minutes of restarting. Repeatedly resetting the system under these conditions can accelerate compressor wear. A proper repair of the root cause is required for the fault to stay cleared.
How much does it cost to repair a Samsung air conditioner showing error 407?
Repair costs depend heavily on the root cause. If the fix is as simple as opening a closed service valve or clearing an airflow obstruction, a service call fee of roughly $75 to $150 may be all that is required. If a faulty EEV, failed fan motor, or damaged filter drier needs replacement, parts and labor can range from $200 to $600 or more depending on the specific component and system model. Refrigerant recovery and recharge adds additional cost if overcharge or a refrigerant-side restriction is involved.

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