This is not an unusual problem whether it is an air conditioner or heat pump. Unfortunately, many times the service technician finds a simple solution that the homeowner could have easily corrected and saved both the cost of a service call plus the inconvenience. can be addressed or fixed by the homeowner. usually require a service call. Emergency switch or shut-off  switch turned off Outdoor disconnect turned off Off on outdoor reset button Unit locked out (reset by turning off then turning back on) Here is a checklist to go through before making a service call: Make sure the thermostat is calling for heating/cooling Make sure no Emergency switches are turned off Make sure circuit breakers for both indoor and outdoor units are in the on position (reset for certainty) Make sure the outdoor disconnect is on Off, on safety device (low pressure, high pressure, low temp, high temp.) Our air conditioner recently stopped blowing out cold air.

When I went to check on it, I noticed that the outside unit wasn't coming on. We had had problems with ants in the contacter in the past, and so I went to take off the lid and check it out. I noticed that the circuit breaker marked "AC" was tripped. Like a good DIYer, I turned it all the way off and back on. It immediately tripped again. In an effort to isolate the problem, I went to the outside unit and pulled the safety connection to disconnect the main power of the outside unit. When I went back and reset the circuit breaker as before, the breaker didn't trip. Reconnecting the outside safety switch caused the breaker to immediately trip again. Later, we tried turning off the air conditioning in the house, resetting the circuit breaker, and turning the AC back on. The circuit breaker didn't trip as soon as it was reset, but when the AC was turned back on inside, it immediately tripped as before. My question is what should I check in this situation? This seems like it can't be an uncommon problem, so I'm sure HVAC professionals encounter this frequently and have a checklist of things to try.

What are the possible causes, remedies, and safety precautions I should consider in this situation? Answers to some comments: No, I didn't see any obvious damage to the wiring near the outside unit. I did look pretty carefully, since I had already taken the panel off to check for ants in the contacter. I didn't try to spin the fan with my hand, and I'm not in a place that I can try this right now. I will try it later today; perhaps in the meantime that could be a step in the diagnosis of the problem if anyone gives an answer between now and then? Likely, future readers of this question will encounter the same problem and some will have a fan that spins by hand and some will have one that is stuck. electrical repair hvac air-conditioning circuit-breaker Start by turning off the breaker, and pulling the serviceman disconnect, which will typically look something like this. This will insure no electricity is flowing to the condenser unit while you're working. Next you'll want to disassemble the unit, to allow access to the electrical parts.

This will vary from unit to unit, so check the owners manual for the procedure for your unit. Once you have the unit opened up, make sure to discharge the capacitors. These things store enough power to kill you, so you don't want them to discharge accidentally.window ac unit storage Resistance is not futileac unit for 1500 square foot home Once the power is completely removed from the unit, it's safe to start poking around (electrically speaking, don't go busting the refrigerant lines). should you cover your ac unit in the winterStart by tracing the wires from the condenser fan motor, back to where they connect in the electrical box. There should be 3 or 4 wires. In my unit, I had Black, White, Brown, and Brown with a White stripe (your model may vary).

To determine if the motor is good, you'll measure the resistance across each coil. To do this, you'll have to disconnect the wires, so the motor is no longer part of the circuit (make note of where the wires connected). Typically you'll have 3 wires, start, run, and common (we'll ignore my 4th wire in this answer). Set your multimeter to measure Ohms, and start measuring. You're going to measure the resistance between each combination of two wires to determine what each wire is, and if the motor is still good. Let's start with Black and White... Black -> White = 15.9 Black -> Brown = 35.4 Brown -> White = 51.2 Common -> Run = Lowest resistance Common -> Start = Medium resistance Start -> Run = Highest resistance We can determine that... If we also know that the two lower readings should always add up to the larger reading, we can safely say this motor is still good. If you measure 0 or infinity between any pair, that means you have a shorted or an open winding and the motor should be replaced.

Repeat the same procedure for the compressor motor. Shorts on the ground The other thing you'll want to check for, is shorts to ground. Set your multimeter up to test impedance. Put one probe on the equipment grounding conductor of the feeder, and the use the other to find a solid ground on the motor. You may have to scratch some of the paint off, especially on the compressor. Once you've found a solid ground, measure from each motor wire to your ground spot. If the meter beeps or give a low resistance reading, you have a short to ground. As with the resistance test above, the motor should be isolated from the circuit when doing this test (once a solid ground is located).Browse other questions tagged electrical repair hvac air-conditioning circuit-breaker or ask your own question.What you will learn from Troubleshooting Broken Thermostats article:One of the most common trouble calls for HVACBasic checks of the thermostat to see if it is broken or?The basics of the thermostatLearn what a heating anticipator is and what type of thermostat uses them.

Lots of related useful links to help you learn your HVAC system Troubleshooting Broken Thermostats - The main connection between the air conditioning and heating system and the end user is the thermostat. Beyond the air conditioning and heating thermostat many people know nothing about their systems that keep them comfortable year round. There comes a time when the thermostat has a problem or the end user wants to replace the thermostat because they think it is a broken thermostat. It is not uncommon for a person to call an HVAC contractor and tell the secretary that they think the thermostat is broken because their air conditioner or heating system does not work.In some instances this is the case while in others the thermostat is not broken but something is wrong with the air conditioning and heating equipment that needs to be repaired. In either case, it is usually best to call an HVAC professional to look at the problem especially if you want to replace the thermostat. There are a few things you can check with your thermostat before you call an HVAC professional.

A little thermostat troubleshooting is in order.Related Link: How to Hook up a New Thermostat - A Closer LookTroubleshooting Broken ThermostatsWhat To CheckAn air conditioning and heating thermostat, even if it is a digital thermostat, is simply a temperature switch that turns the air conditioning and heating system on and off. As with any switch, it needs electricity to function or cause a function with the air conditioning and heating equipment. Most residential and light commercial thermostats are powered by 24 volts A.C. The thermostat gets this 24 volts A.C. from the air conditioning and heating equipment. Usually, this power comes from an air handler in an air conditioning and heating split system and from the main unit for air conditioning and heating package systems. Check the circuit breaker for the air handler to make sure it is not tripped. Also, check the power switch which should be located near the air handling unit. It is not uncommon for people to mistake these switches for a light switch and turn them off.

They unknowingly just turned the power off for their air conditioning and heating equipment including their thermostat. That is when they begin to think they have a broken thermostat. If you have a digital thermostat the power display and the thermostat power display light may not function if you have this problem. Some air conditioning and heating thermostats use batteries to power the backlight which takes us to number two in air conditioning and heating thermostat troubleshooting. Check the power switch and breaker to ensure the power is on before assuming you have a broken thermostatThe back display light for the digital thermostat does not function but the air conditioning and heating system works fine. Check the batteries as some digital thermostats require AA or AAA batteries for the backlight to function on the thermostat.There are two main types of digital thermostats; Digital thermostats that use batteries for the backlight to function and digital thermostats that use the power from the air conditioning and heating equipment.

If you don’t know which kind of air conditioning and heating thermostat you have then open the thermostat up and look inside. If you don’t see any batteries or a battery compartment inside the thermostat then your thermostat uses power stealing technology. It is probably an older model digital thermostat and if it is a programmable thermostat then every time you lose power you will lose the program inside which takes us to the next step in air conditioning and heating thermostat troubleshooting. The programmable thermostat is always losing its program. This is most likely one of the older thermostats that use the power from the air conditioning and heating equipment and every time you lose power you lose the program inside the thermostat. Programming an air conditioning and heating programmable thermostat can be a chore for many people to figure out so a problem like this can be frustrating especially if you live in an area where there are constant power failures. The only solution to this problem is to replace the programmable thermostat with one that uses power stealing technology (it uses power from your air conditioning and heating system to hold the programs) and has a battery back-up just in case you lose power.

This can save you lots of trouble and frustration in the long run keeping you from reprogramming the thermostat over and over again when power failures occur.Related Link: How a Programmable Thermostat Works - A Closer Look If the problem is persistent with the thermostat it is important to get back to thermostat basics.Fix& Broken Thermostats - The BasicsIs the thermostat installed in the proper location? This is very important as a thermostat installed on a wall that has high heat gain or heat loss will never offer you comfort as it will react mostly to the temperature of the wall and not the air in the living space. Additionally, thermostats installed where direct sunlight can hit the thermostat is going to be a problem also. A thermostat located near an outside door or window will be affected every time the door or window is opened or closed. A thermostat should be located close to the return (where the filter is installed) so that it sense and reacts to the air returning to the air handler for conditioning.

Additionally, thermostats located near heat sources like hot or cold water pipes, radiant heaters, fireplaces, electrical devices which produce heat, etc… will never offer accurate temperatures and conditioning for the room(s).Is there a big hole behind the thermostat that will feed cool or warm drafts to the back of the thermostat? All thermostats have a hole behind them where the wires come into the thermostat from the air handling unit. Check this and if you find a big hole behind the thermostat stuff some insulation in this hole and cover it with a piece of tape. This will prevent drafts from affecting the thermostat.Has the heating anticipator been properly set by a qualified air conditioning and heating technician? The heat anticipator is on mechanical non-digital thermostats and needs to be set according to the amp draw on the heating control circuit. The heat anticipator offers a small amount of energy savings and prevents thermostat overshooting for you as it shuts off the main burners because the fan will continue to run and dissipate the heat which remains in the furnace or heat.

Digital and programmable thermostats have built in heating and cooling anticipators which automatically set themselves with no manual adjustments. The mechanical thermostat needs a manual adjustment and you need a tool called an amp meter to determine the proper setting. The cooling anticipator in the mechanical thermostat requires no manual adjustment.If you have a mechanical thermostat with a mercury bulb switching mechanism inside it this thermostat needs to be level. If the thermostat is not level you never get an accurate temperature in the residence or business.Related Link: Learn more about thermostat types - A Closer Look Other problems that can occur with your air conditioning and heating thermostat need to be discussed with an HVAC professional as these problems can be technical and require special tools to fix. It is always a wise choice to call in an HVAC professional when you have problems with your air conditioning and heating equipment including your air conditioning and heating thermostat.