Disclaimer: Always follow your installation manual to the letter when installing a furnace or other appliance. Only trained professionals who are licensed in HVAC should attempt or perform repairs on HVAC equipment as personal injury, death, or property damage could result. Improper service methods can render your equipment inoperable.
Amana/Goodman has made an excellent product over the past decade and there are few problems related to their design, workmanship or parts. Almost none in fact save for the inducer motors and control boards on precious few units. One thing that has carried over from the Amana 90% furnaces made in the 1990's is their drain system. They use a hose from an elbow off the inducer motor and one off the collector box on the heat exchanger. When the furnace is installed, there are typically three hoses and some spring clamps to secure them. The instructions in the manual are pretty straightforward as to how these hoses go, but installers can and do misinterpret them out of ignorance or because beer thirty is just a few minutes away. It could also be that it's perceived to be easier and just as good to do it their way.
I've gotten a few callbacks on Goodman/Amana/Everrest 90 percent furnaces because they will run for a few minutes, stop and after a half hour or so they'll run again. The reason is that the installer will install drain hoses improperly. On a typical install with the furnace straight up, there should be one hose off the bottom of the elbow from the inducer motor and the other off the heat exchanger. The one coming from the heat exhanger must drain on the same side as the drain trap, no exceptions. The long hose is for draining from that elbow if the trap needs to be on the opposite side. No matter what, never use the long hose to drain the heat exhanger, or it will sag in the middle and form a trap of its own. The result is that the heat exhanger will fill up with water and the pressure switch will fail to close. The furnace will fail to operate or operate erratically. Another error is to have the pressure switch tubing routed below the inducer fan, as water will pool here too. Maranatha!