My carrier a/c compressor unit won't start. it just goes ''click-hummmm-click''.installed new filter-old one fairly dirty.both circuit breakers on.furnace blower fan on.new batteries in thermostat and temp set low.

Ensure the compressor is running. It has a large capacitor connected to it that helps the motor to start. They go bad. There is a relay controlled by the thermostat that starts the compressor. It could be as simple as replacing the relay. Now the breaker. There are 2 of them side by side with their handles joined so when one trips so will the other. That isn't always how it works, though. Reset the breaker several times to be sure. There are fuses inside the power disconnect box on the outside of the unit. If one is blown, the compressor won't run

Start your window air conditioner troubleshooting with checking the different modes of operation to see which components operate. Turn the unit fan to on and the cool and heat modes off. If the fan does not operate, check the power supply to the unit. Check to see if the breaker or fuse for the unit is tripped. If the breaker/fuse is tripped, check to make sure that it is the proper size circuit for the unit you have. On some units, there is a current interrupter on the power cord to the unit. Check to see if it is tripped by pushing the reset button.
If the circuit is the proper size, then you can go ahead and reset the breaker/fuse. If it trips again, then you require further troubleshooting. Shut the power off and check all of the wiring in the unit to make sure that none of the connections is loose or damaged.
If the fan does not operate but the fuse/breaker is not tripped, you should check the run capacitor for the fan and compressor. If the capacitor is good but the fan motor does not operate, you can check the fan switch and the fan motor. Ensure that the fan blades spin freely.
If the fan motor operates but the compressor does not start, change the capacitor but first you should feel the compressor with your hand. If it is very hot, then you should allow it to cool.
Then, you should attempt to start the unit in the cooling mode. As you do so, listen for a clicking sound which is an indication that it is attempting to start. If the compressor starts but does not cool properly, the unit may be low on refrigerant.
If the compressor attempts to start but shuts off very quickly, the compressor could be bad. You could try installing a "Hard Start"



If the compressor does not attempt to start, ensure that the thermostat is set below room temperature. On units with a mechanical control, you will hear a click when you adjust the temperature. That is an indication that the thermostat is working properly.

Problem #1:Outdoor condensing fan motor has stopped running. This problem could be caused by a bad motor run capacitor. If your motor capacitor is not the problem, then more than likely you need a new motor. Is the fan blade tight, stiff or hard to turn? If the fan blade is hard to turn then you probably need a new motor. Problem #2: Air conditioner compressor will not start. When power is applied to the air conditioning outdoor unit the fan starts, but you hear a sound like the compressor is trying to start, "UGGG"..., for about 5 to 10 seconds and then all you hear is the outdoor condenser fan run. The compressor is locked and will not start. What is happening is the compressor is trying to start, but because the compressor motor is locked it tries to start for a few seconds and then because of the high amperage being drawn goes off on internal overload. The internal overload protects the compressor windings from overheating and burning up. I see this many times during the start of the air conditioning season. Some compressors just have a hard time starting after sitting all winter long. Some compressors are locked up so bad that I can not start them and must tell my customer that they need a new compressor . Many times I can get the compressor started again without having to buy a new compressor or new air conditioning system by using the device that is called, "Super-Boost." I keep two or three of these on the truck. They have saved many of my customers from having to buy new air conditioning systems.

it could be the compressor or possibly the dual stage capacitor that starts the compressor and runs the fan ,it will be marked with H-for compressor appx35uf./F-for fan at appx 5uf./ and a C-common terminal in the center for the neutral line to both fan and compressor

Yes it is a very big concern.It sounds to me like your condenser is dirty and the compressor gets hot and goes off on overload.You can tell by putting your hand NEAR the compressor.Be careful as the compressor can be very hot

Tripping breakers and your cord getting 'noticeably' warm to the touch are both 'bad' signs - and the most likely problem is either your compressor or fan motor is getting ready to 'quit' on you - which constitutes (in most cases with window units) making the smart move toward a 'new' or 'newer used' air conditioner.

There are however a few things you might try:

First - up-plug the AC and take it out of the window

Second - take the outer cover off - so you can see inside real good. Look for 'loose' electrical connections (loose connections generate excess electrical heat) - "tighten" any connections that are loose. Note: be sure and check the plug - see if the prongs are loose/wobbley, (if so you might need a new cord) check where the cord ties into the window unit - check the electrical components to make sure their connections are good and tight - any wires you find 'wire-nutted' together (with those colored plastic wire nuts) - take them apart and 're-do' them - making sure they are tight.

Check the connectors on the"capacitors" (grey/silver/black items from the size of a pack of cigerettes to 2 or maybe 3 times that big) - make sure they are tight on the connectors.

You may have to take the (spades) off the connector and using pliers - crimp them down so they will fit the connectors good and tight.

On the compressor itself - follow the wires (usually 3) to the little removable cap (usually a metal clip holds it in) - take the clip off and pull the plastic cap out and you can see the compressor terminals. Be sure the wires that are attached (usually with wire spades) are good and tight. If they aren't - carefully remove them - re-crimp and re-install - making sure they are tight. Note: in some cases you might need to put a new spade on the wire.

After doing all that - take a water hose and make sure both coils (evaporator where cold air comes out and condenser where hot air comes out) are good and clean. Note: you don't have to be 'real' careful with the water - but try to not get water in the electrical components/wires.

You have to make sure they are both 'real clean,' and of course the filter that goes in front of the evaporator coil must be clean - but you indicated you've already changed that.

Hopefully - you will find some seriously loose connections and once you get them tight and the unit washed real good - you'll be ok, but if it keeps tripping breakers - and the AC cord continues to feel excessively warm to the touch I would think you will need to start thinking about either a Service Tech to repair the AC or buying a new/different one.

As I noted above - if it's a fan motor or a compressor that is bad - you are better off (since your unit is already 7 years old) in my opinion to try and secure a new AC or a fairly new used one - 'especially if it's the compressor.

If it's the fan motor - and your Service Tech gives you a 'fair' price for a changeout, i.e. 'half' what a brand new unit of the same size would cost - then I'd probably let him do that - but try and get a warranty from him of at least 90 days (parts and labor).

Good Luck!

A circuit breaker 'tripping' everytime the AC unit kicks on 'most always' indicates a direct short (somewhere in the condensing unit), although it is possible that the breaker itself is bad - (but not likely).

Usually the cause of this 'short' will be - either the condenser motor in the condensing unit (outside unit) or the compressor - also in the condensing unit.

If you're mechanically inclined - and "very careful" around electricity - there is a fairly simple way to find out which component is causing the short.

Step 1 - Make sure the condensing unit (outside unit) is completely disconnected (electrically) , i.e. pull the fuses/turn off circuit breaker on outside unit and turn off thermostat.

Step 2 - disconnect the condenser motor (this is the outside fan motor). Note: when you disconnect the wires of the condenser motor "be sure" you mark/write their location, and wrap them in electric tape.

Step 3 - start the AC unit. If the breaker trips again you can pretty much rest assured it's the compressor that is shorted.

To prove it (without a doubt) - go to next step.

Step 4 - "be sure circuit breaker and thermostat is turned off" - and - 'reconnect' the condenser motor - and - then disconnect the compressor wires (mark wires and tape them).

Step 5 - Start AC.

If breaker doesn't trip - you know it's the compressor that is shorted.

If breaker 'does' trip again - then it's possible the breaker itself is bad (not likely) or there is a 'short' in the condensing unit's "wiring" somewhere (not likely).

My guess is that either the condenser motor or compressor is shorted.

Hope this helps.

Good Luck!

A 20 amp circuit breaker should be sufficient enough to do the job unless the breaker itself is too old, or if the connection screws on the breaker are not tight enough.

With the jumper inplace does the compressor start? What about without? Unless you have more than one transformer you should leavethe jumper.

Sounds like you either blew a transformer, have a bad circuit breaker or blew the main fuse in the outside disconnect. If the indoor unit is still blowing air (no matter what temperature) start looking at the power supply to the outdoor unit. From the circuit breaker, the power will go to a small box located within a few feet from the outside unit. This box will have either a lever on the side or you will be able to open the box and pull out the fuses. From this box the power goes to the condensor. The first thing you should do is to turn off the breaker to the outside unit. Flip it back on and if you have a call for cooling, after about 3 minutes the outdoor unit should start. If it does not, shut off power again to the unit by switching off the breaker, go outside and pull out the fuses in the disconnect box. Using a multi meter, check for continuity thru the fuses. If you have continuity, call your technician. If one or both fuses show no sign of continuity, replace the fuse(s). Make sure that the thermostat is working and sending a signal to the indoor air handler. You may be able to check this by turning the fan switch to "Fan" and see if the blower turns on. You may just have a bad thermostst. Caution should be used anytime you are near electrical components. If you do not have the skill-set required to test electrical equipment, leave it to a proffessional.