The digital display on the Bryant/Midea multi zone ductless mini splits allows for troubleshooting on an outdoor unit, similar to what is possible on the indoor unit. Follow the instructions in this video to troubleshoot and understand fault codes on your unit.
Improper gas pressure can cause issues with your furnace if it is not properly set at the time of the installation. Overheating or under-heating can result in problems, ranging from damage to the furnace to not properly heating the space as intended.
Usually, you sell new equipment, install it, and move on. However, there are a lot of add-on items you might be missing that can easily be sold on every job and will not only increase profits but also add value for your customer.