3709815C94 | Genuine International® Air Brake Twin Compressor For MaxxForce 13, 11

• Provides braking power

  • Compresses air and sends it to the air tanks (reservoirs).

  • When the driver presses the brake pedal, that stored air is released to apply the brakes.

• Maintains air pressure automatically

  • The system includes a governor valve that starts and stops the compressor to keep air pressure within a safe range (usually around 100–130 psi).

• Powers other pneumatic systems

  • Besides brakes, compressed air also runs:

    • Suspension systems (air ride)

    • Air horns

    • Transmission controls

    • Door systems (on buses)

• Ensures safety and reliability

  • Air systems don’t leak or boil like hydraulic fluid, making them ideal for heavy-duty trucks that require powerful, reliable braking under heavy loads.

1. Slow Air Pressure Build-Up

The system takes longer than normal to reach operating pressure (typically 100–130 psi).
Indicates worn compressor pistons, valves, or air leaks.
If it takes more than 3 minutes to reach full pressure from empty, that’s a red flag.

2. Excessive Air Leaks

Audible hissing around the compressor or fittings.
Could mean damaged gaskets, fittings, or cracked lines.
Persistent leaks make the compressor run continuously, causing overheating or failure.

3. Overheating or Unusual Noise

Grinding, knocking, or rattling noises from the compressor area.
Often caused by worn bearings, connecting rods, or broken internal components.
Overheating can lead to oil breakdown and internal scoring.

4. Oil Carryover / Contamination

Oil found in air tanks or lines indicates the compressor is passing oil through the system.
Can damage valves, air dryers, and other pneumatic components.
Usually caused by worn piston rings or seals.

5. Frequent Governor Cycling

Compressor turns on and off too often.
Suggests air leaks, faulty governor valve, or compressor inefficiency.
May also indicate the compressor is undersized or struggling to maintain pressure.

6. Air Dryer Problems

Air dryer purging too often or spitting oil.
Often a symptom of compressor overwork or oil carryover.
If the dryer is constantly active, check compressor output first.

7. Warning Lights or Fault Codes

On modern trucks, low-air-pressure warnings or fault codes may appear on the dash.
If the low air pressure warning buzzer sounds frequently, it’s a strong indicator of compressor or system trouble.

8. Visible Damage or Leakage

Oil leaks around the compressor body or clutch housing (for clutched types like 3709815C94).
Cracked or corroded fittings may also signal internal wear.