GeneralTroubleshooting2026-02-26
Thermostat Not Working: Troubleshooting
Dead batteries, wrong settings or a lost link cause most thermostat problems.
A faulty thermostat is one of the most common — and cheapest — heating complaints.
Common causes
Dead batteries, a blank screen, wrong mode, an aggressive schedule, or a lost wireless link stop the thermostat working.
What to do
Replace batteries, confirm HEAT mode and re-pair wireless units; wiring or compatibility issues need a technician.
Key takeaways
- Replace batteries first
- Confirm HEAT mode and schedule
- Re-pair wireless thermostats
- Smart thermostats may need a C-wire
Need help with your general?
Licensed, gas-certified technicians serving Greater Vancouver since 1999. CombiBoiler.ca — A division of ROMA Heating Ltd..
Frequently asked questions
More General articles
Water Leak Emergency: The First 5 StepsFast, calm action limits water damage from any HVAC or plumbing leak.How to Find Your Water Shut-Off ValveKnowing where your main and appliance shut-offs are can save thousands in water damage.No Heat in Winter: An Emergency GuideWhatever your heating system, here's how to respond safely when the heat goes out in winter.How to Detect a Hidden Water LeakUnexplained bills, damp spots and a moving meter can reveal a hidden leak before major damage.When to Call Emergency HVAC ServiceSome issues can wait for a scheduled visit; others need immediate response — here's how to tell.Preventing Water Damage from HVAC LeaksDrain pans, leak sensors and maintenance prevent costly water damage from boilers, furnaces and water heaters.
More from our knowledge base
Furnace Won't Turn On? Causes and FixesFurnaceFurnace Blowing Cold Air: What to CheckFurnaceWhy Your Furnace Short-Cycles (and How to Stop It)FurnaceNo Heat? Emergency Furnace Repair GuideFurnaceFurnace Making Strange Noises: A Sound-by-Sound GuideFurnaceAnnual Furnace Maintenance ChecklistFurnaceAll ArticlesBrowse the full library