California Air Tools 4620AC Review - Ultra Quiet Series

CAT-4620AC Review - In case you haven’t heard (no pun intended) of California Air Tools, they specialize in manufacturing reduced noise air compressors. The CAT-4620AC is from the “Ultra Quiet Series” of contractor grade air compressors. With a noise level of only 70 dB the California Air Tools 4620AC is one of the quietest 2 HP air compressors in the industry. This compressor was a top 5 choice in our Quietest Air Compressor for Garage or Shop category.

California Air Tools CAT-4620AC review.

California Air Tools CAT-4620AC

CAT-4620AC Quick Specifications:

  • 70 Decibels - Ultra Quiet Series
  • 2 HP 1680 RPM SP Series Motor
  • Oil-Free Dual Piston Pump
  • 5.30 CFM @ 90 PSI
  • 4.6 Gallon Twin Aluminum Tanks
California Air Tools 4620AC Review

California Air Tools 4620AC Review

California Air Tools 4620AC

ASIN: B005SOD08M - UPC: 743369740209

4620AC Product Video

SP9421 2 HP Pump Motor

CAT-4620AC California air compressors use a durable high performance two horsepower SP-9421 motor/pump. The new SP series are easily repaired; however, the long-life SP pumps are rated for 3000 hours of use before repair. SP pumps are designed for improved heat dissipation which increases the compressor’s duty cycle and allows for longer continuous run times before requiring a cooling break.

To help with noise reduction the cast aluminum pump utilizes two extra-large pistons with Teflon coated rings powered by an ultra-quiet 1680 RPM four pole electric motor. Compressor air flow is increased using improved stainless-steel Swedish reed valves and a redesigned valve plate.

CAT-SP9421 2 HP Ultra-Quiet Pump

CAT-SP9421 2 HP Ultra-Quiet Pump

The 2 HP brushless induction motor is UL Listed and features thermal overload protection to help protect the motor against damage due to accidental overheating.

California Air Tools 4620AC ultra-quiet air compressors are equipped with an easy start valve that bleeds a small amount of air from the pump during startup. This creates a temporary no-load condition, making the air compressor very easy to start and reducing startup current load. The easy start valve provides lower amperage cold weather starts and ensures longer pump and motor life.

In addition to being maintenance free, the pump’s oil-free design helps with cold weather starting and enables use on uneven terrain since there is no oil in the pump. However, page 9 of the CAT-4620AC owner’s manual states, "For proper operation, the air compressor must be placed on a flat surface with an incline no greater than 15 degrees", so you wouldn't want lay the compressor on its side.

California Air Tools 4620AC Left Side View

CAT-4620AC - Left Side View

California Air Tools 4620AC Right Side View

CAT-4620AC - Right Side View

The 4620AC uses a popular twin horizontal tank design with two rust free 2.3-gallon aluminum tanks for a total tank size of 4.6 gallons. The powerful 2 HP ultra-quiet SP-9421 pump produces air flow of 6.40 CFM @ 40 PSI or 5.30 CFM @ 90 PSI and quickly fills both air tanks from empty to the maximum rated pressure of 125 PSI in only 60 seconds and recovers from the kick-in air pressure switch setting of 95 PSI to a full 125 PSI in a speedy 20 seconds.

This compressor draws 14 Amps, so you won't want other electrical devices running at the same time on the branch circuit. The manufacturer states that the CAT-4620AC can be operated using a 14 gauge or larger extension cord of up to 25 feet. Truthfully, I wouldn’t recommend any extension cord on a 2 horsepower or larger compressor. Extension cords can cause a voltage drop at the compressor’s electric motor which will result in poor performance and cause overheating and possibly damage. If you need to operate your compressor at a distance from the electrical outlet, then the best solution is to use a longer air hose. When the compressor’s power cord is connected directly to an electric outlet the unit will run better and last longer.

If you intend on using the CAT-4620 as a stationary compressor or have access to 220 volt AC wherever you intend to use the compressor then you might want to consider the California Air Tools CAT-4620AC-22060 which is a 220 volt model of the same air compressor with a 7.5 amp draw.

Just in case you don't know anything about decibels or dB sound ratings, they use a logarithmic scale, which simply means that a 70 decibel compressor is twice as quiet as an 80 decibel model. Watch the sound comparison video below to get an idea of what an ultra quiet air compressor like the California Air Tools CAT-4620AC sounds like in comparison to a standard noisy pancake compressor.

CAT-4620AC Review - Sound Comparison

Two air pressure gauges, dual universal ¼” quick air connectors, and the pressure regulator controls are conveniently mounted on a steel control panel. The compressor features rubber feet on the tubular steel frame and a padded carry handle.

The unit is portable, but at 67.5 pounds many CAT-4620AC reviews list being heavy as a con. There is no wheel kit, so you’ll need to heft the compressor around using the carry handle. Though most 2 HP and larger portable air compressors are somewhat heavy, so this complaint is not unexpected.

Other complaints from California Air Tools 4620AC reviewers included poor packaging and a less than ridged control panel. Poor packaging was the number one complaint among the customer reviews, with some saying their compressor was damaged during shipping.

This compressor includes two silencing air filters to filter airborne particulates and help quiet the compressor. Don’t forget to attach the filters to the motor heads. The filters are in the bottom of the packaging and easy to overlook. You will realize quickly because the compressor will sound much louder if you forget to install the intake mufflers.

California Air Tools 4620AC

ASIN: B005SOD08M - UPC: 743369740209

California Air Tools 4620AC Silencing Filters

CAT-4620AC Silencing Air Filters

CAT-4620AC Top View - Air Filters Installed

The air filters should be cleaned regularly. Simply remove the filter covers with a slight twist to access the filter elements. Blow out the filter elements with compressed air or use a brush to remove the accumulated dust and debris or and reinstall. The intake air filters appear to be popular Solberg silencing filters with a couple of lengths of sound reducing tubing attached although California air lists #90260 as the part number for the air filter.

Solberg Silencing Filter

Solberg Silencing Filter Element Removal

CAT-4620AC Resources

California Air Tools 4620AC Specifications

  • 70 dB Quiet
  • 5.3 CFM @ 90 PSI
  • 4.6 Gallon Total
  • 2.0 HP Dual Piston
  • 14 Amps
  • Long Life
  • Dual PSI Gauges
  • Low - 1680 RPM
  • Length 19.1"
  • Width 16.7"
  • Height 19.6"
  • 67.2 Lbs.

Our CAT-4620AC Ratings


California Air Tools specializes in producing quiet air compressors. 70 dB for a 2 HP compressor is a good noise reduction.


California Air Tools is a leader in the quiet air compressor industry, and the quality built into the 4620AC is no exception. 


The CAT-4620AC typically sells around $400 to $450, which is competitive for similar 2 HP quiet air compressor models.

Overall Rating :  4.5

This model provides a good combination of power vs sound. A little louder than the CAT 1 HP models but with a dual piston pump for increased airflow of 5.3 CFM at 90 PSI it packs more power. We gave the CAT-4620AC air compressor an overall rating of 4.5 stars


  • Air Flow 5.3 CFM 
  • 4.6 Gallon Aluminum Tanks
  • Efficient 2 HP Motor
  • Excellent Buyer Reviews


  • Weight 67.2 Lbs
  • Current, 14 Amps

"Designed for the person looking for Power, Air Flow, Less Service and Maintenance with at Least 30% Less Noise!"

California Air Tools

The Bottom Line

If you are looking for a contractor grade, reasonably quiet air compressor with plenty of power, then take a close look at the California Air Tools Ultra Quiet Series 4620AC compressors. Its 2 HP oil-free pump and 4.6 gallon air storage tanks make this an adequate size compressor for many users, and a noise level of only 70 dB will certainly be appreciated by anyone in the area. If you are interested in a very similar 2 HP reduced noise air compressor with a larger 10 gallon tank then you might want to check out our California Air Tools 10020C Review.

California Air Tools 4620AC

ASIN: B005SOD08M - UPC: 743369740209

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