If your digital thermostat is blank, check the batteries. Some thermostats have batteries in them while others don't. If your thermostat has batteries, replace them and see if the display appears immediately.
Float Switch
Check your float switch at your air handler and see if there is water present. This may be the cause of your thermostat going blank. If you are comfortable with clearing your drain line with a shop vac, this may solve your problem.
Check Breaker
Locate your breaker panel and verify the breaker hasn't tripped. If you reset your breaker and it trips again within a month, you will need a professional to diagnose why it keeps tripping. Make sure you tell the professional that it tripped prior and how long in between. DO NOT KEEP RESETTING BREAKERS.
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