honeywell t9 won't let me set the heat above 90 degrees, is that a limit or is mine broken?

It's a limit, not a bug. The thermostat has a built-in safety and practicality range to prevent you from accidentally (or intentionally) overworking your system.

The acceptable temperature ranges are hard limits:

• Heat Mode: 40°F to 90°F (4.5°C to 32.0°C). You literally cannot set it higher than 90.
• Cool Mode: 50°F to 99°F (10.0°C to 37.0°C).

So if you're trying to set it to 92 for heat, it won't take the command. The desired temperature display just won't go past 90.

IF THAT DIDN'T WORK: If you're within the range (say, 85°) and the temperature setting still isn't changing, make sure you're actively adjusting the setpoint. Touch the up/down arrows on the screen. If the screen is asleep, press the center area of the displayed temperature to wake it up first.