A thermostat that works until heating starts presents a different problem from a display that is always blank. If the screen turns off or reboots during a heating call at your Loomis home, document that timing. It can help a technician investigate an interruption instead of replacing the thermostat on appearance alone.
Distinguish a sleeping screen from a restart
Some displays dim or sleep as part of normal operation. Consult the owner’s manual for the normal wake-up behavior. A repeated startup logo, lost connection message or visible power warning is a different observation. Say exactly what the screen shows and whether the room continues warming while the display changes.
A loss of Wi-Fi also is not necessarily a loss of thermostat power. If the wall display still works while the phone app reports the device offline, include that distinction in the service request. The app and the equipment are not always reporting the same condition.
Track the point at which the display changes
Note whether the screen fails as soon as you select Heat, after the furnace begins humming or when air starts moving. Do not repeat the cycle just to collect more examples. If you already have an error message or short video taken safely, save it.
Mention whether a thermostat, doorbell transformer, HVAC accessory or other control-related component was recently installed. Do not assume two changes are connected, but give the technician the installation history so that possibility can be evaluated.
Why another battery may not solve the problem
Power arrangements vary. Some thermostats rely on replaceable batteries; others receive power from the heating system. Follow the model instructions for user-replaceable batteries. If the problem persists, the technician may need to evaluate the thermostat supply and how it behaves during operation.
A furnace fuse, wiring issue, transformer problem or safety-circuit interruption requires testing to identify. Do not install a larger fuse, improvise a common-wire connection or bypass a drain switch. A display that wakes up after a reset does not prove the underlying condition has been corrected.
Combine the screen history with the heating symptoms
Report whether the furnace or heater is not turning on, makes clicking noises, runs briefly or loses airflow at the same time. Also mention any new furnace smell. A gas odor or carbon monoxide alarm calls for evacuation and emergency help from outside; it should not be treated as a thermostat repair problem.
Our Loomis intermittent-heating guide explains how to preserve useful observations when equipment works again before the appointment.
Ask for a focused power diagnosis
For Loomis furnace repair, call (916) 666-0074. Tell us that the thermostat loses power during a heating call and ask about current scheduling. If emergency heat repair is needed, confirm availability and make a safe warmth plan. Do not use an oven to heat the house while waiting.