Problem with this unit

Is the compressor running? Is the unit getting power to the motor? Unless that motor is running nada is going to work.

If the compressor is getting power and it is not running then the unit has seized. It will hum for a bit and then blow the circuit breaker.

If the compressor uses a starting capacitor, check to make sure that it is good.

Your question does not include what type of system you are asking about, but the assumption is that it is a heat pump. The loud humming is the compressor running by itself while the fan is off.

This is the typical way a reasonably new heat pump operates:
There is a coil temperature sensor that initiates a defrost period to eliminate the frost/ice build up on the outdoor coil. In the defrost mode, the outdoor fan shuts off and the reversing valve in the heat pump reverses the direction of refrigerant flow to warm the outdoor coil. The same coil temperature sensor senses the temperature of the external surface of the coil and tells the defrost control when the frost is gone initiating another 'reverse cycle' to put it back into heating mode. In the heating mode, the outdoor fan runs again.

If you have the heat pump installed where snow drifts accumulate, you will have a problem extracting heat from the outdoor air, and coil frosting and freezing will be exaggerated. If you have excessive ice build up due to a defosting issue, the ice can actually stop the fan from rotating, but you would hear loud bangind and rattling for hours first as the fan blades come in contact with the ice.

If you do not have drifts, but continually have an excessive amount of ice build up, either the sensor is possibly faulty or the defrost control board is faulty. The sensor's clip could easily have been knocked loose from the coil by ice and is no longer sensing coil temperature and if so the result would be the lack of defrost initiation.

dirty filters in the indoor unit.As the ambient temperature rises the unit will work harder and longer,its fine when its just a normal day because the evaporator coil wont have time to ice up as the compressor will cycle off before the coil freezes totally,but during extreme ambient temperatures the coil will ice up as the compressor will continue running to reach set-point causing the coil to ice up

Hi!!
It could be many things, the most common are Low R22 refrigerant, bad fan motor, bad compressor. obstructed condenser coil, bad starting relay, bad capacitor. among other things.
To check fan motor, set unit to HI Fan Only setting and let it run for a while, check that fan did not loose speed and it is not getting too hot.
If fan is OK, then turn unit to HI Cool 60-65 degrees and see what happens. Hear if compressor kicked in or if just made a humming noise and stopped. if this happens, replace capacitor.
Keep me posted!! Rate this post!!

It does sound as if you may need a new ice maker. Other than that does the compressor come on to keep the ice cold? If so is it making any type of noises beyond the typical hum?

Are you sure the humming noise is from the compressor motor being locked up? It is normal for the compressor motor to make a humming noise when it runs. Make sure the fan in the freezer is also running while the compressor motor is running and replace it if necessary.

You need to defrost the coils in the back of your freezer. You can do this the slow, easy way by simply unplugging the refrigerator for 24 hours. Leave the doors open to ensure everything has the chance to melt.

The fast way to defrost the coils is to turn off the refrigerator and remove the rear panel from the freezer compartment. You will see the evaporator coil completely frozen with ice. Thaw the ice with a hair dryer and make sure you thaw the drain at the bottom of the back wall as well.

When you turn replace the freezer panel and turn the refrigerator back on, it will get cold again.

When you shut it off and back on it slugged the compressor if you turn it off and back on before the pressures equalize between the high and low sides it will slug the compressor and it will not run should let sit for five minutes or so before restarting. The humming is either the compressor making noise usually common for the compressor to make some noise or the fan motor bearings are getting bad on the outside unit. If the unit works normal probably not much you can do till it breaks if it is the compressor it is more economical to replace the whole unit if it is just the fan motor it is worth changing. You could take an amp draw on the fan motor and the compressor to see if the are within the limits on the name plate of the outside unit.

f the refrigerator isn't cool, you need to answer some questions, then see if the compressor is running.

First, answer these questions:

• Is the refrigerator completely dead? If so, see “It's stopped completely.”



• Is the thermostat knob turned to the proper setting? If not, reset it.

Next, see if the compressor motor is running

The compressor is a football-sized case with no apparent moving parts. It's on the outside of the refrigerator at the back near the bottom. If it is humming or making a continuous noise and your refrigerator is still not cooling, there may be a more serious problem with one or more of several different components, we recommend contacting a qualified appliance repair technician for further help.

If the compressor is not running but you do have power to the refrigerator, there may be a problem with one or more of these:

• The compressor



• The Thermostat



• The overload, relay, or capacitor



• The defrost timer



• The condenser fan motor

Before giving up on the compressor you should do the following:
1. The compressor is evidently not running. You can try to start it manually instead of allowing the refrigerator start unit to do so. If it then runs you need a new start/overload unit...about $20 to $60 depending on where you get it. Do not continue to allow the unit to cycle off and on with the overload as that can eventually cause compressor harm. To start it manually the best way is to unplug the frige and completely unhook everything from the 3 compressor terminals. If your unit has a start capacitor you should then short it with a wire or screwdriver to discharge the capacitor to prevent you from being shocked with the fridge even unplugged. Then make up a test setup with wire so that you can apply 120 vac between the run (R) and common (C) terminals. The test set up wiring should include a push button switch to make momentary connection between the start(S) and run(R) terminals. Then with your wiring connected as described plug the test wiring into an outlet and push the button for 2 or 3 seconds and then release. Do not hold the button down longer. The compressor should start and run. If it starts your compressor is ok. If it does not start to run then your compressor may be bad...or...it may be stuck internally with a speck of grit or something and it may still be possible to get it unstuck with additional procedures. If the compressor runs starting it manually you can turn your thermostat to very cold and the compressor will continue to run perhaps long enough for you to buy the start/overload replacement parts and keep your food from thawing.
2. If the compressor will not start manually then according to "Modern Refrigeration & Air Conditioning" bookby althouse/Turnquist/Bracciano you can perhaps start the stuck compressor by:
A."Connect the 120 vac motor compressor into a 240 vac power circuit using a starter cord. One must be careful. Press the push-button switch for only a second at a time or the motor will be damaged. the extra voltage may break the stuck compressor loose."
B. "An extra torque method is to connect a 240 V, 100 mfd(microfarad) start capacitor across the terminals of the run capacitor for no more than one second. (Count "one thousand one.") This may free the compressor.

If none of the above starts your compressor it will need to be replaced.

see if the compressor motor is running

The compressor is a football-sized case with no apparent moving parts. It's on the outside of the refrigerator at the back near the bottom. If it is humming or making a continuous noise and your refrigerator is still not cooling, there may be a more serious problem with one or more of several different components, we recommend contacting a qualified appliance repair technician for further help.

If the compressor is not running but you do have power to the refrigerator, there may be a problem with one or more of these:

• The compressor



• The Thermostat



• The overload, relay, or capacitor



• The defrost timer



• The condenser fan motor