Master Flow Q90 150 psi Heavy Duty Air Compressor

• Heavy duty air compressor
• Maximum working pressure 150 PSI
• 30 minute duty cycle
• Overheating protection circuit
• Complete with carrying cse

I bought this compressor because my buddy had good performance with a Q89 compressor. I did not realize the performance increase from the Q89 to the Q90 was so vast. We both run 38 x 12.50 x 15 tires on our Jeeps. The Q89 takes three minutes to pump each tire from 6 PSI to 30 PSI. The Q90 takes only two minutes per tire. I love the performance.

Three issues with the compressor:

1) The compressor draws about 40 amps from the battery, if you have the engine off while pumping up four tires, the engine is slow to crank. If you pump up eight tires, the Jeep needs a jump to get started. I may be experiencing battery end-of-life, but I have learned to let the engine run during tire filling. Running the engine while pumping runs the compressor measurably faster and significantly reduces refill time.

2) The compressor head and outlet pipe get very hot during use. The handle is too hot to handle after pumping up four 38 inch tires. The hose disconnect is too hot to handle with bare hands after pumping up two 38 inch tires. The plastic hose supplied with the kit melted next to the hose disconnect. It did not fail, but the distortion makes it look like it is going to fail. I replaced it with a rubber hose that handles the heat much better.

3) The screw on valve attachment was rather restrictive. When I replaced the plastic hose with the rubber hose, I also replace the screw on valve attachment with a NAPA clip on inflation valve. The compressor now runs cooler, draws less current, fills the tire faster, and it is faster to move from tire to tire around the Jeep.

About half the people that have used my compressor want to buy one to replace the one they have now.

One thing about my application: I pump my tires up to only 30 PSI, therefore the 150 PSI capability is not required. The design could be improved by having a user adjustable cutoff switch to turn the compressor off when a final pressure is reached. If the compressor is running and forgotten while the engine is off, then the tire will be unsafely overinflated and the battery will be dead.

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