Homeowner Guide
A thermostat problem can look like a broken AC, but it can also be a symptom of a drain safety switch, wiring issue, power problem, or equipment fault. Before guessing, note what the display and equipment are doing.
If the screen is blank, check whether it uses batteries, whether the breaker has tripped, and whether the indoor unit has power. Do not keep resetting breakers if they trip again. Repeated trips or hot electrical smells should be treated as a safety warning.
Set the thermostat to cooling and note whether the indoor blower starts, whether the outdoor unit starts, and whether the temperature reading seems believable. That short set of clues helps Scott separate thermostat setup from a real $95 Springfield Diagnostic issue.
Read the thermostat service pageIf the display works but the system does not respond, the AC starts and stops, water is present, the outdoor unit hums or clicks, or the breaker trips, request a diagnostic instead of assuming the thermostat is the only problem.
