subject: Air Conditioner Won't Turn On? Thermostat Check [print this page] At home in the summer there are few situations worse than having your air conditioner go out. Even with multiple ceiling fans, the comfort of an air conditioner is greatly missed. The miserable experience can be quite costly to remedy, but we have put together a list with a few steps to help you if you're having trouble with your central air conditioner system automatically turning on. Please review and go through the following steps before calling an AC repair specialist. Hopefully, it's just the thermostat and you can save some money and feel good about doing a little DIY (do it yourself).
1) Make sure the air conditioner is on and set the thermostat to "cool." Check that the displayed set temperature is well below the current temperature or the real temperature of the room. Five to ten degree should be enough.
2) Your central air conditioner should have its own dedicated 240-volt circuit. Locate the main electrical box (or panel) usually located on one of interior garage walls (in older homes it may be located outside). Check for a tripped breaker or a blown fuse. If the air conditioner breaker is tripped or blown, reset or replace the fuse.
3) Check that the furnace power switch is in the on position. Next, look for a switch mounted on the outdoor unit. This is the condenser's on/off switch. Make sure that it's off. Now, make sure the 240-volt breaker, which is next to the compressor (it should be in a metal box typically located on the exterior house wall adjacent to the unit) is still on. In some cases the breaker is a switch or a removable circuit. Regardless, make sure it is off or out of the on position.
4) Double check to make sure the power to your air conditioner is off. Now, head back inside and check the thermostat. Take off the outside housing on the thermostat. It usually snaps or easily unscrews off. When opened, unscrew the Y terminal wire and turn the power back on.
5) Now we can perform the troubleshooting tests. Grab the wire by its rubber covering. Do not touch the metal with your fingers. It can shock you. Take the metal exposed portion of the Y wire and hold it to the R terminal for a couple minutes. If the compressor turns on, you have a faulty thermostat. This is rather inexpensive. It's recommended that you call a qualified air conditioning repair expert. If the compressor does not kick on, this unfortunately means it's not the thermostat which means it can be a number of different problems. Turn the power off and contact a qualified air conditioning repair expert.
