VIAIR 400P-RV - User Manual

Questions and Answers

J
Jermaine HendersonJul 28, 2025
What to do if VIAIR Air Compressor has low airflow or cannot reach high pressures?
- L
  Lori PerkinsJul 29, 2025
  If your VIAIR Air Compressor's airflow is lower than normal, or it cannot pump to higher pressures, it could be due to a worn piston ring or inlet valve. Service or replacement of the compressor is recommended.
G
gonzalezronaldAug 5, 2025
How to troubleshoot a VIAIR 400P-RV Air Compressor that will not run?
- C
  Craig GonzalezAug 5, 2025
  If your VIAIR Air Compressor won't run, first ensure the compressor switch is in the ON position. A blown fuse could also be the culprit; disconnect the compressor from the power source and replace the fuse, referencing the Specifications section for the correct amperage. Lastly, the motor might be overheating. If so, let the compressor cool off for about 30 minutes to allow the thermal overload switch to reset.
A
Abigail BeckerAug 12, 2025
What to do if the thermal overload protector keeps cutting out on my VIAIR Air Compressor?
- T
  Theresa RichardsonAug 12, 2025
  If the thermal overload protector in your VIAIR Air Compressor repeatedly cuts out, it may be due to a lack of proper ventilation or a high ambient temperature. Try moving the compressor to a well-ventilated area or an area with a lower ambient temperature. Alternatively, the compressor valves may have failed, requiring a compressor replacement.
L
Lauren JohnsonAug 19, 2025
Why is my VIAIR 400P-RV making excessive knocking or rattling noises?
- R
  Rachel JohnsonAug 20, 2025
  Excessive knocking or rattling in your VIAIR Air Compressor could indicate a worn bearing on the eccentric or motor shaft, or a worn cylinder or piston ring. In either case, service or replacement of the compressor is recommended.

Summary

Operating Instructions

Tire Inflation

Steps for connecting the hose and tire gun, and inflating tires to the desired pressure.

Tire Deflation

Procedure for decreasing tire pressure using the tire gun's bleeder valve.

Inline Pressure Gauge

Explanation of how to use the integrated gauge for monitoring tire pressure.

Safety Precautions

Maintenance & Repairs

Guidance on cleaning, lubrication, and authorized service for the compressor.

Summary

Operating Instructions

Tire Inflation

Steps for connecting the hose and tire gun, and inflating tires to the desired pressure.

Tire Deflation

Procedure for decreasing tire pressure using the tire gun's bleeder valve.

Inline Pressure Gauge

Explanation of how to use the integrated gauge for monitoring tire pressure.

Safety Precautions

Maintenance & Repairs

Guidance on cleaning, lubrication, and authorized service for the compressor.

The VIAIR 400P-RV Automatic Portable Compressor, Heavyweight Series (Part No. 40047), is a 12-volt, permanent magnetic motor air compressor designed for inflating tires and other articles. It is a robust and versatile air tool, ideal for RV owners and others who require a reliable portable air source.

Function Description:

The 400P-RV is an automatic portable compressor that provides compressed air for various inflation needs. It is equipped with a built-in pressure switch that automatically turns the compressor on at 130 PSI (± 5%) and off at 155 PSI (± 5%), protecting the unit from over-pressure operation. This automatic feature allows for convenient and hands-free inflation once the desired pressure range is set. The compressor comes with a primary coil hose, an extension coil hose, and a tire inflation gun, enabling both airing up and airing down of tires. The included 45-degree extended reach angled chuck and 90-degree twist-on chuck facilitate access to difficult-to-reach inflation valves.

Important Technical Specifications:

Part Number: 40047 / 400P-RV Automatic
Motor Voltage: 12-volt
Motor Type: Permanent Magnetic
Max. Intermittent Pressure: 150 PSI
Max. Duty Cycle: 33% (20 minutes on / 40 minutes off) at 72°F & 100 PSI. This means the compressor can operate continuously for 20 minutes, followed by a 40-minute cool-down period, to prevent overheating and ensure longevity.
Max. Current Consumption: 30 amps
Fuse: 40 amp
Inline Pressure Gauge: 160 PSI (Tolerance: ± 3%)
Built-in Pressure Switch: 130 PSI / On, 155 PSI / Off
Automatic Reset Thermal Protection: Yes. This feature automatically cuts off power to the compressor if its internal operating temperature rises above safe levels, preventing permanent damage. The compressor will automatically restart once it has cooled down.

Usage Features:

The 400P-RV is designed for ease of use and safety.

Operation: Always operate the compressor at or below its maximum pressure rating and observe the maximum duty cycle to prevent damage. It is recommended to keep the vehicle's engine running while using the compressor to prevent draining the vehicle's battery. The compressor should only be operated in well-ventilated areas, and its performance is enhanced when the vehicle engine is running.
Connection: Before connecting the power clamps to the vehicle's battery terminals, ensure the ON/OFF switch is in the OFF position. Attach the Positive (+) battery clamp (Red) to the Positive terminal and the Negative (-) battery clamp (Black) to the Negative terminal of the battery.
Tire Inflation: To inflate tires, attach one end of the extension coil hose to the compressor and the other end to the tire gun kit, using either the 45-degree angled chuck or 90-degree twist-on chuck as needed. Turn the compressor switch ON and hold down the trigger on the tire gun kit to begin inflation. Release the trigger once the desired pressure is reached.
Tire Deflation: The tire inflation gun also allows for deflation. With the inflation option still connected, press the bleeder valve button on the tire gun kit to decrease tire pressure. Release the button to stop deflation.
Inline Pressure Gauge: The pressure gauge on the inflation gun provides convenient tire pressure monitoring during airing up or down. However, for accurate readings, release the lever on the tire inflation gun during inflation to check the tire air pressure, as air velocity can affect readings.
Excess Pressure Release: To release excess pressure from the coil hose after use, turn off the compressor, disconnect the hose from the compressor, and with the tire inflation gun still connected to the other end of the coil hose, pull the trigger on the tire inflation gun.
Safety Precautions: Never exceed recommended tire pressures to avoid over-inflation and serious injury. Use heat-resistant, minimum 200 PSI-rated working pressure extension hoses. Avoid touching the compressor or fittings with bare hands during or immediately after use, as they can become very hot. Wear heat-resistant gloves if necessary. Never place the compressor in soft sand while running, as vibration can cause it to draw in foreign particles. Do not expose the compressor to water while running.
Automatic Restart: If the compressor shuts off due to the thermal overload protector, turn the ON/OFF switch to the OFF position and allow it to cool for about 30 minutes before resuming use.
Pressure Switch Behavior: During inflation between 130 PSI and 155 PSI, if inflation is stopped, the compressor may not restart immediately because the inline pressure is greater than the cut-on pressure but less than the cut-off pressure. To restart, deflate the tire pressure to below 130 PSI, reconnect the tire chuck, and resume inflation.
Delayed Start: A slight delay in the motor starting when the ON/OFF switch is turned on while the compressor is pressurized (i.e., when there is pressure in the line) is normal and not a malfunction.

Maintenance Features:

The VIAIR 400P-RV is designed for low maintenance.

Motor: The compressor is equipped with a permanently lubricated, maintenance-free motor. Do not attempt to lubricate the compressor.
Cleaning: Regularly clean dust and dirt from the compressor cooling fins and motor housing to ensure optimal performance and prevent overheating.
Air Filter: Ensure the air filter element is properly installed in the Inlet Air Filter Assembly. Remove the temporary protective red plug from the compressor's air inlet port and hand-tighten the inlet air filter. Replace the filter element periodically for optimal compressor performance, as a clogged filter will drastically reduce flow rate and performance.
Repairs: All repairs should be performed by the manufacturer or manufacturer-authorized service agencies only. Do not disassemble or attempt repairs or modifications yourself.

This compressor is a reliable and essential tool for anyone needing portable air, offering automatic operation, robust construction, and important safety features to ensure efficient and safe use.