Red Bull Fridge — Dumpster Rescue & First Diagnostics

Work in Progress — Diagnostic Stage
A serendipitous appliance repair project, learning about refrigerator repair and electronics.

I was walking home when I spotted a Red Bull-branded mini-fridge abandoned next to the garbage.
It was dirty, heavy, and almost certainly broken — so obviously I took it home. I’ve always wanted one. They are COOL.

This thing weighs approximately “way too much.”

Data sheet says 95 lbs

Dragging it inside was… athletic. I should maybe have rethought my life choices… But I finally found a dolly for the home stretch.

Eventually I got it up the stairs and into the apartment:

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First Power Test

When plugged in, nothing happened — bad sign — the compressor didn’t even try to start.
No hum, no click, just silence.

Time for diagnostics.

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Opening It Up

The back panel revealed:

• A compressor and fan (standard fridge guts)
• A small relay module (suspicious)
• A simple power input board with Potentiometer
• An accessory power brick feeding off the input board. Probably for the front lights

Based on symptoms, my first suspects were:

1. Bad Starter Relay and Overload Protector (hopefully)
2. Bad Compressor Relay
3. Power board traces / input connector
4. The compressor itself (hopefully not)

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Wiring Diagram

flowchart LR

  %% === AC SUPPLY (vertical stack) ===
  subgraph AC["AC Supply"]
    HotBus["AC Hot (L)"]:::hot
    NeutralBus["AC Neutral (N)"]:::neutral
  end

  %% === POWER INPUT BOARD + POT (vertical stack) ===
  subgraph PB["Power Input Board + Controls"]
    Board["Power Input Board"]:::board
    Pot["Potentiometer<br/>(Temp Setpoint)"]:::ctrl
    CtrlOut["Control Signal<br/>(to Relay)"]:::ctrl
    AuxPS["Aux Power Supply<br/>(Lights / Display)"]:::board

    Board --> Pot
    Pot --> CtrlOut
    Board --> AuxPS
  end

  %% === RELAY (single box, still grouped) ===
  subgraph RLY["Compressor Relay"]
    Relay["HF115F-012-1H3AF Relay"]:::relay
  end

  %% === COMPRESSOR CIRCUIT (vertical stack) ===
  subgraph COMP["Compressor Circuit"]
    Overload["Overload Protector"]:::protect
    Run["Run (R)"]:::comp
    PTC["PTC / Start Device"]:::comp
    Start["Start (S)"]:::comp
    Common["Common (C)"]:::comp
    Overload --> Run --> PTC --> Start
  end

  %% === FAN ASSEMBLY (vertical stack) ===
  subgraph FAN["Fan Assembly"]
    FanHot["Fan Hot"]:::hot
    FanMotor["Fan Motor"]:::fan
    FanNeutral["Fan Neutral"]:::neutral
    FanHot --> FanMotor --> FanNeutral
  end

  %% === MAIN LEFT → RIGHT FLOW BETWEEN GROUPS ===
  HotBus --> Board
  Board --> Relay
  Relay --> HotSw["Switched Hot"]:::hot

  %% Control path (Pot → relay logic)
  CtrlOut -- "Temp Control" --> Relay

  %% Compressor connections
  HotSw --> Overload
  NeutralBus --> Common

  %% Fan in parallel
  HotSw --> FanHot
  NeutralBus --> FanNeutral

  %% Aux supply neutral return (optional but clear)
  NeutralBus --> AuxPS

  %% === COLOR STYLES ===
  classDef hot fill:#4a1d1d,stroke:#ff8080,color:#ffecec,stroke-width:1px;
  classDef neutral fill:#1d2a4a,stroke:#80aaff,color:#e6f0ff,stroke-width:1px;
  classDef board fill:#333333,stroke:#bbbbbb,color:#f5f5f5,stroke-width:1px;
  classDef relay fill:#4a3a1d,stroke:#ffcc80,color:#fff7e6,stroke-width:1px;
  classDef comp fill:#1d4a2a,stroke:#80ffb3,color:#e8ffef,stroke-width:1px;
  classDef fan fill:#163b4a,stroke:#66d0ff,color:#e5f9ff,stroke-width:1px;
  classDef protect fill:#4a321d,stroke:#ffb366,color:#ffecdd,stroke-width:1px;
  classDef ctrl fill:#3a1d4a,stroke:#d080ff,color:#f7e6ff,stroke-width:1px;

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The Multimeter Comes Out

Compressor Resistance Test:

• The compressor leads measured normal resistance
  (no shorts to ground, no winding imbalance)
• Jumping the relay started the compressor AND the fan
  → meaning the compressor works, and the power supply is fine. Not option 4.

That narrows it down dramatically.

I decided to swap out the Starter Relay and Overload Protector mounted to the compressor as these are a common problem, but no such luck. Not option 1.

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The Relay: Probably Evil

Here’s the relay the fridge shipped with:

This is the villain of the story.

Based on the datasheet and what I saw in-circuit:

• Relay does not click
• Zero volts at compressor terminals through relay
• But full voltage when jumped around it
• Most importantly: continuity through the coil is inconsistent, sometimes briefly non-zero, sometimes nothing
  → Dead relay coil is the most likely failure.

I pulled the part number:

HF115F-012-1H3AF
Common refrigerator compressor relay: cheap, and apparently fragile.

Replacement cost: $6–$10.

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Current Status

So far, the fridge:

• Powers on (when relay is bypassed)
• Lights work
• Fan works (when relay is bypassed)
• Compressor runs (when relay is bypassed)
• Compressor runs under control of the relay
• Actually cools my Red Bulls
• Sold for profit (if my wife hates it). They go for crazy high prices on facebook market and eBay (200-500$)

Based on the tests, I’m now 90% sure the relay is the issue.

New relay is on the way.

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Next Steps

• Replace the HF115F relay
• Inspect input board traces for heat damage
• Clean interior + replace seal
• Add thermometer + data logging because why not (may be low-priority but is a fun learning opportunity)
• Replace missing ‘l’ on front (currently says “Red Bul”)

When the new relay arrives, I’ll post a follow-up to see if this thing becomes a functional fridge… or goes back to the street from whence it came.

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