A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
A malfunctioning thermostat has a harder time maintaining a setting, and may quickly shift temperature settings with no warning. If your central air has a difficult time maintaining the set temperature, even after lowering a setting for a test trial, it could be the thermostat.
Blank or unresponsive screen
If your thermostat has fresh batteries but suddenly lacks power, flashes, or isn't responsive to adjustments, it may need replacement. If resetting the thermostat doesn't resolve the problem, you may have wiring problems or faulty components causing your thermostat to not turn on.
A bad thermostat could certainly cause the ac not to work. You can check the t'stat by removing it from the wall and jump the red wire to the yellow (R to Y) at the wall plate. That should cause the outdoor ac to run. If it does run then the t'stat is bad.
Any time you are having an issue with heating and cooling units, such as after a sudden power failure or after your children have had 'control' of the system while you've been away, resetting the thermostat should be the first thing you try when attempting to rectify HVAC system issues.
There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.
In most cases, installing a new thermostat is a relatively simple do-it-yourself project that can result in improved comfort and convenience and one that can help you save energy.
While there is a small chance that there is an issue with the running temperature of your engine, by far the most common issue with trouble code P0128 is a faulty thermostat. The exact location of the thermostat and issues related to a damaged thermostat may vary depending on your vehicle.
Replacing your thermostat when you install a new AC system is a great idea. The connection between the thermostat and AC is important to the function of the system. Problems with the thermostat can cause the AC to run more often than it should or not as often as it should.
One of the most obvious signs that your home's thermostat needs replacing is that it has faulty temperature readings. You'll notice that the indoor temperature reading is nowhere near what it actually feels like.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
You can typically just replace the outdated thermostat with a new thermostat – assuming the latter is compatible with your HVAC system. There are a few things you should know, however, when upgrading your thermostat.
Moving a Thermostat: If the required wiring exists at the desired location, moving a thermostat may cost as little as $65. However, moving the unit can entail installing new wiring and cutting and patching drywall, so the project can cost up to $450.
One of the most obvious signs you need to replace your thermostat is when it doesn't do anything. If your thermostat display doesn't light up or respond when you press buttons or try to change the settings, you may have to replace it. Before assuming you have a broken thermostat, make sure it has fresh batteries.
This can occur when there are blockages or restrictions in the air ducts, preventing the cool air from reaching your home. Common causes of airflow problems include dirty air filters, blocked vents, and debris in the air ducts.
High temperature readings
The main symptoms of a failing thermostat are related to engine overheating. It can be easily noticed because the temperature gauge in the vehicle will probably read unusually high. This can be caused by the valves being stuck in a closed position.
Switch the thermostat to the off position. Locate the breaker that powers your HVAC system and turn it off. Wait 30 seconds and turn the breaker back on. Turn your thermostat back on and confirm it has reset properly.