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Silver metal compressor unit with black sealed switch and mounting brackets

VIAIR

VIAIR 40042 400H hardmount compressor kit 33% duty sealed 12 V 150 PSI 2.54 CFM 35 in

SKU CH-HQKG-AB8SB

12 V compressor kit delivers 2.54 CFM at 150 PSI with 33 % duty cycle for tyres up to 35 inches

  • Product typeAir Compressors
  • 12 V sealed compressor runs with engine on
  • 150 PSI maximum working pressure for demanding tasks
  • 54 CFM free flow at 0 PSI for fast inflation
  • 33 % duty cycle suits intermittent off-road use
  • Good for up to 35 inch off-road tires

Purpose and Fit

The VIAIR 40042 400H is a hard-mount 12-volt air compressor kit built for off-road vehicles needing on-board inflation. It suits drivers who want a permanently installed unit for tyres up to 35 inches. Not for buyers who need an integrated air tank or a portable carry-handle model.

Thermals Noise Power

The compressor runs at a 33 percent duty cycle, so it requires cool-down periods during extended airing sessions. The engine must be running to supply adequate voltage at the 150 PSI maximum working pressure. The environmentally sealed on/off switch protects the electrical contacts from dust and moisture.

Deciding Spec

The 2.54 CFM free-flow rating at 0 PSI determines how quickly the unit fills large off-road tyres. This flow figure is the single specification that tells you whether the compressor matches your tyre size and inflation-time expectations.

How it compares

Measured against everything we stock in Portable Air Compressors, at today’s prices. Recalculated every night.

Price $240.99
Pricier than about 91% of the 61 comparable items (median $55.99).

Specifications

Product
Product typeAir Compressors

Questions about this item

How is the VIAIR 40042 400H compressor hardmounted and what wiring step is often missed?

Bolt the compressor to a solid frame rail using the included bracket, then run a fused power lead straight to the battery; the step people skip is fitting the relay so the motor only draws current when the engine is running.

What maintenance will the 400H kit need after extended off-road use?

Check the environmentally sealed pressure switch for grit, clean the intake filter screen, and verify the 33 % duty cycle limit has not overheated the head; re-torque mount bolts if vibration loosens them.

What limit appears first when airing up four 35-inch tyres back-to-back?

The 33 % duty cycle at 150 PSI forces a cool-down pause after roughly ten minutes of continuous run time before the 2.54 CFM flow can resume safely.

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