VIAIR 93940 40 Amp Air Compressor Relay for 12 Volt Compressors

(13 customer reviews)


40 Amp 12v Relay with Mounting Tabs. Available in 1 or 2-packs.

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  • Four 1/4 inch spade post connectors
  • Handles up to 40 amperes maximum ampere draw in applications
  • Each compressor must have its own relay for a proper installation
  • Mounting tab for relay molded into moisture resistance relay case
Connector Type Quick Connect
Contact Material Silver Nickel
Current Rating 40 Amps
Mounting Type Chassis Mount

Wiring Diagram


Additional information

Weight 0.8 lbs
Dimensions 6 × 5.5 in


13 reviews for VIAIR 93940 40 Amp Air Compressor Relay for 12 Volt Compressors

  1. GMF

    No issues
    Seems fine

  2. Wreckerdan

    Great product

  3. John

    Works good
    Been on for almost a year now and still works fine, plastic mounting tabs usually worry me but this one is sturdy.

  4. s w

    As described and good value for the price.
    Simple, inexpensive robust (40 amps). I use it to run my bilge pump to cut down on burning out bilge pump switches. I have used other realys for this purpose, the all seem to work OK, but this was a very good price and most other relays are only 30 amps. I don’t know if there is really a difference, but will go with the specs. arks are arks, the bigger the contacts the longer they last. Of course with all of this kind of stuff, until it has been in for a few years we really don’t know do we? But it looks good so far.

  5. nick minnema

    These are perfect I’d order again
    Came quickly and worked perfect

  6. Charlie H.

    I have 2 and they work flawlessly

  7. Jim

    Works great

  8. Matthew Harnden

    I got this to replace the one on my ARB Air compressor. Fit perfectly and my compressor works perfectly now

  9. Jay R.

    I only had to replace my last Viair relay because I broke the mounting tab, it was working perfectly for over 6 years in outdoor conditions exposed to direct sunlight, frost, and the elements. I’ve used no-name relays before and they never last this long.

  10. David Allday

    The two plastic pieces comes apart easily.

  11. Mitch owen


  12. RV Customer

    These are a great replacement relay for anyone with an air lift performance system. We’ve all been there when something goes weird just to find out the relay is bad. Quick switch out and direct fit.

  13. NewGold

    It will either work or it won’t.

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