ARB twin compressor cycling every 45 seconds — the $18 check valve fix

My ARB twin compressor (CKMTA12) started cycling every 45 seconds when the tank was supposedly full. Built-in pressure switch was cutting in at 80 psi, but the tank was actually at 120 psi — the check valve had failed and was leaking back through the pump head.

I ordered a replacement ARB check valve (part #ARB11800054, $18 on Amazon). Pulled the old one: the rubber seat was cracked and the spring was weak. The new one threaded in with Teflon tape in 30 minutes. Fired up the compressor, filled to 150 psi, shut off at 120 psi with the ignition. Held pressure for 3 weeks before I used it. Now 3 months later, still no cycling.

If your ARB compressor cycles on and off without air tools engaged, don't assume it's the pressure switch. Check the valve first — it's a $18 fix vs $85 for a new switch assembly.