AC Refuses to Start or Stops Suddenly: A thermostat that's not working correctly might fail to initiate the cooling cycle or might randomly shut off the AC. This erratic behavior can be due to electrical issues or miscommunication with the AC unit.
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.
A thermostat is responsible for turning on and off the air conditioner's compressor and fan. The thermostat senses indoor temperatures and uses this data to determine when the rest of the HVAC system needs to run and when to stop; i.e. it's a switch connected to a temperature sensor.
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.
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.
The standard thermostat has a series of wires that connect to the HVAC system. One wire turns the blower on, one turns it off. Another wire turns on the compressor to start the cooling cycle, another turns it off. If a wire comes loose or frays or corrodes, the thermostat will lose one of its key functions.
HVAC System Suddenly Quits Working
Try replacing the batteries, then check for a blown fuse or tripped breaker in the electrical panel. If the thermostat is still unresponsive, make sure the breaker is shut off and remove the cover.
Your thermostat reads the temperature of the room, then sends an on or off signal to the air conditioner. The AC itself isn't detecting the temperature in your home, so it has to rely on the thermostat.
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.
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.
One of the most common reasons why an air conditioner might be running but not cooling a house is due to thermostat issues. The thermostat is responsible for controlling the temperature of your home, and if it's not functioning properly, it can cause your AC unit to work inefficiently.
Replacing a Thermostat. You'll pay between $15 and $300 for the unit in addition to labor ($65 to $100 per hour) to replace an old thermostat with a new one. However, installing a brand-new thermostat is more involved and, therefore, more expensive.
Checking basic thermostat settings, power supply components, and air filter conditions are essential to troubleshoot why an AC unit isn't turning on. More advanced issues requiring professional attention include faulty wiring, a malfunctioning outdoor unit, a bad capacitor, or incorrect thermostat calibration.
Clean the Thermostat
Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.
A malfunctioning thermostat will have trouble keeping your home's temperature at the right setting. If there's something wrong with the motherboard, it may change its own settings at random. You can test the thermostat by lowering the settings to see if the problem persists.
Signs of a Faulty Thermostat
AC Refuses to Start or Stops Suddenly: A thermostat that's not working correctly might fail to initiate the cooling cycle or might randomly shut off the AC. This erratic behavior can be due to electrical issues or miscommunication with the AC unit.
If you can't see any mechanical or cleaning issues, contact an HVAC professional. Broken thermostat: A faulty or broken thermostat is a common cause of a frozen AC.
Temperature Fluctuations: One of the most common signs of a bad thermostat is erratic temperature readings on your dashboard gauge. If you notice that the temperature gauge moves from normal to hot quickly or fluctuates unexpectedly, it's a clear indication that your thermostat may be malfunctioning.
You should be able to turn on your heating or cooling system from the thermostat, or change operation back and forth from heating to cooling. If you make changes at the thermostat and get no response whatsoever from your furnace, air conditioner, or heat pump, it could mean the thermostat is bad.
On average, most thermostats last about 10 years, depending on the model, usage, and proper maintenance. However, many people decide to replace their unit sooner to take advantage of new energy-saving technologies.