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Error code reference

Mitsubishi Air Conditioner Error Code E.UVT

Undervoltage

Mitsubishi codesMitsubishi air conditioner codes

Undervoltage - power supply voltage decreased to about 150 VAC (300 VAC for 400V class) or below, inverter output shut off.

First step from the service manual

Check if a high-capacity motor is driven, check jumper across P/+ and P1, and check power supply system.

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

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What E.UVT means on a Mitsubishi air conditioner

The E.UVT error code on a Mitsubishi air conditioner indicates an undervoltage fault condition detected by the inverter drive circuit. Specifically, the fault triggers when the incoming AC power supply voltage drops to approximately 150 VAC or below on standard 200V class units, or to approximately 300 VAC or below on 400V class systems. When this threshold is reached, the inverter output is automatically shut off as a protective measure to prevent damage to the power transistors, compressor motor windings, and other sensitive inverter components that cannot operate safely under severely reduced voltage conditions.

The inverter section monitors supply voltage continuously during operation. When voltage sags below the protective threshold, the control board registers the undervoltage condition and cuts inverter output immediately. A key component in this circuit is the DC bus link between terminals P/+ and P1. A jumper is normally installed across these terminals in most standard configurations, and if that jumper is missing or has failed, the DC bus voltage will be artificially low even when incoming AC power is adequate. This is one of the first hardware checks specified for this fault code.

Common system-level causes include utility grid voltage sags, shared power infrastructure with large motor loads, undersized wiring causing excessive voltage drop under load, and weak or failing power supply connections. High-capacity motors starting on the same electrical circuit can produce significant instantaneous voltage drops that trigger this protective fault. Investigating the power supply quality at the unit, verifying the P/+ to P1 jumper is intact, and reviewing the electrical load profile of the installation are the primary starting points for diagnosis.

Source: manufacturer service documentation.

Common causes of E.UVT

  1. 01

    Utility or site voltage sag

    Wiring / connection

    The incoming AC supply voltage is dropping below the minimum threshold of approximately 150 VAC (200V class) or 300 VAC (400V class). This can result from utility grid instability, peak demand periods, or heavily loaded branch circuits. Measure voltage at the unit's disconnect with the system under load to confirm.

  2. 02

    Missing or failed P/+ to P1 jumper

    Part replacement

    A jumper connected across terminals P/+ and P1 on the inverter board is required for proper DC bus operation. If this jumper is absent, corroded, or has failed, the inverter will register an undervoltage condition even when supply voltage is adequate. Inspect the terminal block and verify the jumper is securely installed.

  3. 03

    High-capacity motor on shared circuit

    Wiring / connection

    Large motors such as compressors, pumps, or industrial equipment starting on the same electrical circuit can cause sudden, significant voltage drops that trigger the E.UVT fault. Review what other loads share the supply circuit and check for voltage dips during motor start events.

  4. 04

    Undersized or degraded supply wiring

    Part replacement

    Wiring that is too small for the load, or conductors with damaged insulation and high resistance, can produce excessive voltage drop when current draw increases during compressor start. Measure voltage drop from the panel to the unit under load and compare against acceptable limits.

  5. 05

    Loose or corroded power supply connections

    Wiring / connection

    Poor connections at the disconnect, contactor, or terminal block increase resistance under load and cause localized voltage drops. Inspect all power terminals for discoloration, corrosion, or looseness and retorque or replace as needed.

See the test procedure for each cause

Frequently asked questions about E.UVT

What does E.UVT mean on a Mitsubishi air_conditioner?
E.UVT is an undervoltage protection fault. It activates when the AC power supply voltage drops to approximately 150 VAC or below on 200V class units, or to approximately 300 VAC or below on 400V class units. When this occurs, the inverter output is automatically shut off to protect the compressor and drive electronics from operating under unsafe voltage conditions.
Can I fix an E.UVT error myself?
Some causes, such as a tripped breaker or a shared circuit being overloaded by another appliance, may be identifiable without professional help. However, diagnosing internal inverter components like the P/+ to P1 jumper, measuring DC bus voltage, and safely working inside the inverter section requires electrical knowledge and proper safety precautions. A licensed HVAC or electrical technician is strongly recommended for full diagnosis and repair.
Is it safe to keep running the air conditioner with an E.UVT error?
No. The E.UVT fault causes the inverter output to shut off automatically as a protective measure. Attempting to bypass or repeatedly restart the unit without addressing the underlying voltage issue can damage the inverter power transistors, compressor motor windings, and control board. The root cause should be corrected before the system is returned to service.
Will resetting the unit clear the E.UVT error?
A reset may temporarily clear the fault display, but if the underlying voltage problem has not been corrected, the error will return as soon as the inverter detects the low voltage condition again. A persistent E.UVT code that returns after reset indicates an ongoing supply voltage issue or a hardware fault such as a missing P/+ to P1 jumper that must be addressed directly.
How much does it cost to repair an E.UVT error on a Mitsubishi air conditioner?
Repair costs vary widely depending on the cause. If the issue is simply a missing or failed jumper across the P/+ and P1 terminals, costs could range from a few dollars in parts to a standard diagnostic service call fee. If the problem involves electrical supply upgrades, new wiring runs, or inverter board replacement, costs could range from several hundred to over a thousand dollars. A technician assessment is needed to provide an accurate estimate.

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