Thermostat not working or inaccurate
The thermostat is the system's brain. When it's blank, wrong or miswired, a perfectly good AC can look broken.
Schedule thermostat service
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Thermostat problems are often simple: batteries, settings or a schedule nobody remembers programming. Others involve control wiring, compatibility with a smart thermostat, or heat pump configuration. We'll help with the simple checks over the phone.
What you might notice
- Blank or flickering display
- Reads a different temperature than the room feels
- Doesn't respond to setpoint changes
- Smart thermostat shows errors, loses Wi-Fi control or lost power after installation
- Heat pump runs on auxiliary heat too often
Common causes
Batteries and power
Dead batteries, a tripped float switch or a failed transformer.
Settings and schedules
Wrong mode, a hold or a schedule overriding manual changes.
Location
Direct sun, drafts, nearby vents or lamps skew the reading.
Wiring and compatibility
Many smart thermostats need a common (C) wire, and heat pumps need correct configuration.
Failed thermostat
Sensors and relays fail with age.
Safe checks you can make first
- Replace the batteries
- Check the mode (Cool), the setpoint and the fan setting (Auto)
- Look for a hold or schedule overriding your changes
- If a smart thermostat was just installed, check the app's wiring and system-type settings
How a Uniform technician diagnoses it
We check control voltage at the air handler and thermostat, verify each wire's function, confirm the configuration for your equipment (single-stage, two-stage, heat pump, aux heat), and check the reading against a calibrated thermometer.
Repair options
| Option | When it fits |
|---|---|
| Reconfigure settings | The thermostat is set up for the wrong system type. |
| Repair wiring or add a C wire | Control wiring is damaged or a smart thermostat needs constant power. |
| Relocate | The location gives false readings. |
| Replace or upgrade | The thermostat has failed, or you want a smart or humidity-sensing model. |
You get a written estimate after diagnosis and before any work starts. See what changes a quote in our Naples AC repair cost guide.
Why homeowners choose Uniform
The technician who comes to your home has passed a guaranteed background check and works for a licensed, insured air conditioning contractor. Florida license number posted at launch. Verify any Florida A/C contractor at DBPR.
Request a call back
Tell us what's happening and we'll call you to schedule. Every visit starts with diagnosis and a written estimate.
Other AC problems: ac not cooling, ac won't turn on, ac leaking water, frozen ac coil, weak airflow, ac runs constantly, ac noise or smell, high ac electric bill, heat pump problems.
Frequently asked questions
Can I install a smart thermostat myself?
Many people do. Heat pumps, multi-stage systems and missing C wires are where problems start. If the system behaves oddly afterward, call.
Why does my thermostat say 'Aux Heat'?
On a heat pump, it means backup electric heat is running. Frequent aux heat can indicate a configuration or heat pump problem.
Should I set my fan to On or Auto?
In Florida, Auto is usually better for humidity. On can re-evaporate moisture from the coil back into the house.
Need an HVAC tech you can trust in your home?
Call now. We'll ask a few questions, give you an honest arrival window and send a background-checked, licensed technician in uniform.
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