I had a maintinence man call me and describe what sounded like a broken compressor. It's a First Co. hotel unit. The condenser was dirty and compressor was near max LRA. Rated for 6.6, running at 6.3. On shutdown, compressor had a wicked backspin, rattling and knocking for 15-20 seconds. I figured "this is easy, dirty condenser coil." After cleaning, it runs cooler and RLA dropped to a proper 5.0. But the comp. still backspins loudly. I don't have operating pressures as this is a sealed system w/no access valves. Temp drops are about 16 degrees and the "touch" of the lines tells me it is properly charged. Operates properly except for the rattle. Do these small 1.5 ton units have a built in check valve to prevent this from happening?