No matter what the problem, we’re here to help. Before you call for service, try these simple tips for troubleshooting air conditioners. Is it getting power? Check your fuses or circuit breakers to make sure they don't need to be present Remember, if your home's power is out or disconnected, your system may not work Is the thermostat set correctly? Make sure your thermostat has power Check that your thermostat is set to cooling or heating mode and not set to "off" Make sure the thermostat is set to the right setting and temperature No Heat / Insufficient Heat Do you have a new or newly remodeled home? Was any work done on your fuel or electricity lines recently? Check to see if your gas or electricity has been turned off. If this is the case, having it turned back on may solve the problem. Check to see if your thermostat is on, and what temperature it's set at. If your thermostat is turned off or set incorrectly, turn on and/or reset thermostat.

Check your home's circuits and fuse box. ac unit doesn't workIf you have an open circuit breaker or burned-out fuse, switch on the circuit or replace the fuse.how to fix a leaking window ac unit Remove any snow drifts resting against your outdoor unit.outside ac unit will not start Review our list of Heating System Symptoms & Repairs No cooling / Insufficient cooling Check the doors and windows in your home. Close any open doors or windows as cool air may be escaping through them.If your thermostat is turned off or set incorrectly, turn it on and/or reset thermostat. Review our list of Common A/C Compressor Symptoms & Repairs Check around your outdoor unit. If there are any leaves, hedges or property walls butting up against it, your system may have frozen up due to a dirty coil.

Make sure your outdoor unit has 1' of clearance all around it. Check the filters in each of your system components (where applicable). If any of your filters are dirty, consult your manual to clean or replace it. Or call your dealer to do this for you. Check to see if there is any air coming through your vent. Your indoor blower may not be operating. If this is the case, you should contact your dealer. Review our list of Air Flow Symptoms Stale and stuffy air If you have a whole-home air cleaner or air exchanger, make sure it is switched on and its filter is clean. For even more tips on improving your indoor air quality, click here. Review our list of Common Indoor Air Quaility Symptoms Too dry or too much moisture in the air Check to make sure your humidifier is switched on. Many times, homeowners turn off the humidifier at the end of the previous heating season and forget to turn it back on when needed. Make sure your humidifier’s damper or water valve is open.

If it’s closed, consult your manual to open or unclog. Check your humidifier setting and adjust the indoor relative humidity settings to bring greater comfort to your home. Review our list of Whole House Humidifier Symptoms A high pitched sound often, although not always, indicates a lack of return air. Make sure your return and supply vents are open and free of any blockages including furniture. Other noises (e.g., rattling, humming, thumping or scraping sounds) could be a sign of undersized or flimsy duct work, clogged filter or wear and tear on your system’s internal components. If you hear an unusual sound, call your local dealer for service. Review our list of Common AC & Furnace SmellsIs the thermostat the problem? When we have our central air fan set to "on," it runs fine, but when we set it to "auto," the fan does not come on even though the AC compressor kicks in.  (The AC unit is working fine...It comes on and produces cool air). This means that we have to keep the fan on constantly when we want the AC on. 

Do we need to replace the thermostat? It didn't seem to have this problem throughout the winter when we had the heat on and the fan set to "auto." Not what you were looking for ? Ultimately, you may have to replace the thermostat. But before you do, try these steps: 1) Thermostat switches make electrical contact across two very small conductors that carry a very low energy signal. This means a low-energy battery, without enough energy to create the required signal, can result in problems like you're experiencing. First step ... purchase a fresh battery and replace the old one. Move the temperature and fan switches to the "Off" position and then return to your preferred settings. Allow several minutes for the thermostat to "cycle." Then determine if the compressor and fan have come on; 2) Because the thermostat conductors are very small, if the switches are slightly out of position and they will not conduct the required energy to transmit a signal to the fan and compressor. 

Try simply wiggling the switch back and forth gently across the "Auto" position and allow it to stop as you feel it click into the "Auto" position. Allow several minutes for the thermostat to "cycle" and determine if the compressor and fan have come on. These are two easy steps that may allow your system to work. Since you report the thermostat working fine in the "Heat" position, I would expect it to work just as well in the "Cool" position. I hope one of these simple fixes works! However, if these steps do not work, thermostats are relatively inexpensive and the included instructions make it fairly easy to install. Make certain you purchase a thermostat for the type system you have (ex. heat pumps often take a different thermostat that compressor systems). Then, pay attention as you remove the old thermostat and reinstall the new thermostat following the color codes on the instructions. Finally, if none of these steps work, have a reputable licensed AC contractor service the unit.

Most units that are serviced regularly provide efficient service for many years. I have taken these steps many times in the transition between heating and cooling seasons, and I'm always pleased that I didn't turn a small repair into an unnecessary, much larger repair bill. NOTE: This is a great time to change your air filter. Check the size and purchase a replacement while you're at The Home Depot. A Plumbing Associate will be happy to discuss your options. Relays/capacitors are commonly damaged by power surge ... lightning is a common enemy of this part! The visible indicator is the canister swells like it wants to burst. Relays are beyond most DIYer's desire or ability, so I didn't include it in my earlier list. If you were able to identify the item, a local A/C supply house would likely stock the part and may or may not sell it to you ... some require licensure to sell any of their parts while others will sell non-regulated supplies to anyone.

Unless you are particularly handy with electrical, I would save my resources for that reputable, licensed repair shop. You may find the solution another way, but having your annual service and including this repair is likely a good idea. I really like to "Fix It" when I can, but there are times when you just have to let go and call a pro! This may be one of those times. A Quick Warning: "Start Relays/capacitors" build up energy and discharge that energy to help start electric motors. This discharge can give you a very real shock!!! Be very cautious if you decide to proceed on your own. You are soo welcome, Jennie! When you resolve the problem, take time to come back and explain what you found and how you resolved the problem. I'm certain you'll be adding very useful information to the body of knowledge here on The Community. I have a Carrier Gas Furnace and a Hunter Fan Thermostat 41110. The thermostat will not let me set date or time and/or move button up and down to set temperature.