Viair 90-120 PSI Pressure Switch with 40A Relay



The Viair 90-120 PSI Pressure Switch with 40A Relay is a heavy-duty pressure switch that features a built-in 40 amp relay to increase durability and simplify the install. When the air pressure in your tank drops below 90 PSI, the Viair 90-120 PSI Pressure Switch with 40A Relay will automatically activate your compressor until the pressure reaches 120 PSI and then automatically shut you compressors off. The Viair 90-120 PSI Pressure Switch with 40A Relay sets the standard for reliability, tested to last over 10,000 cycles and pre-fitted with insulated 1⁄4” male push-to-connect terminals. The Viair 90-120 PSI Pressure Switch with 40A Relay makes installation much easier with the built-in relay and clearly labeled lead wires.

Compatible With

Use With The Following To Run At 120 PSI:

  • Viair 275C (Partnumber: AC-275)
  • Viair 280C (Partnumber: AC-280)
  • Viair 325C (Partnumber: AC-325, AC-325C)
  • Viair 330C (Partnumber: AC-330, AC-330IG)
  • Viair 350C (Partnumber: AC-350, AC-350C)
  • Viair 400C (Partnumber: AC-400, AC-400C)
  • Viair 450C (Partnumber: AC-450, AC-450C, AC-350IG)

May Be Used As A Replacement With:

  • 150 PSI Shocker Train Horn Kits (Partnumbers: HK-S4-***)
  • 150 PSI AirChime Train Horn Kits (Partnumbers: HK-P3-5**, HK-P5-5** HK-K3-5**, HK-K5-5**)
  • 150 PSI Outlaw Train Horn Kits (Partnumbers: HK-C3-***, HK-C3B-***, HK-C3M-***)
  • HornAir 150 PSI Onboard Air Systems (Partnumbers: HA-***)
  • Viair 150 PSI Onboard Air Systems (Partnumbers: AS-****)
  • Moisture Resistant
  • Built-in 40 Amp Relay
  • Viair 90-120 PSI Pressure Switch with Built-in Relay
  • Part Number: PS-120R
  • Ports: 1x ⅛″ NPT male
  • Turn-Off Pressure: 120 PSI
  • Restart Pressure: 90 PSI
  • Voltage: 12 Volts DC
  • Max Amps: 40 Amps
  • Length: 4.25″ (107.95 mm)
  • Width: 2.25″ (57.15 mm)
  • Weight: 1 lb (0.45 Kg)
Refunds, Returns, & Warranty
  • Money-Back Guarantee/Refund Policy
    All merchandise unless otherwise indicated may be returned within 30 days from the shipment arrival date for a refund. A Returned Merchandise Authorization (RMA) number is required for all returns. A 15% restocking fee may apply. Additional deductions may be made to reflect the products current market value. These terms apply to all refunds. Most products are shipped with a refund/replacement guarantee period unless otherwise noted in the product listing. Customers must inform of any order discrepancy within 7 days from the invoice date so that we may investigate and resolve the situation accordingly.
  • Warranty
    This product is backed by Viair's One-Year Manufacturer's Defect Warranty!
  • Satisfaction Guarantee offers our customers a 30-day satisfaction replacement or refund guarantee on all purchases, except when otherwise noted in the product listing.
  • Cross-Shipments will not cross-ship returned merchandise.
  • Physical Damage Policy
    Physical damage to any product purchased at will effectively void warranty coverage. Physical damage includes but is not limited to improper handling and/or any other type of damage sustained by irregular usage.


This product can expose you to chemicals including lead, which is known to the State of California to cause cancer, birth defects or other reproductive harm. For more information, go to