Goodman heat pump manuals are available on the official Goodman website, as of 2015. The website offers heat pump manuals for several different models, including the Goodman ComfortNet 16 and 18 Seasonal Energy Efficiency Ratio heat pumps.
From the Goodmanmfg.com main page, click "Residential Products" in the top menu. Click the Heat Pumps image. Select the appropriate heat pump model for which you need a manual. Click on the blue Product Specifications icon near the top of the page. Depending on your Internet browser settings, the manual opens in a new browser window or downloads to your hard drive in PDF format.