[canofworms]

It seems to only ice up at night. If we use it all night I wake up and cool air is not coming out. I take the front off and it is iced up. Or if I set the timer early in the morning it ices up. What causes this. I heard it is something to do with the temp outside. Please give me your advice what to do with it.

thanks

[libertyappl]

Generally there's more moisture in the air at night. Turn it down so it cycles more often. See if that helps
Nat

[SublimeMasterJW]

Clean or change the filter
clean the coils with some good penetrating coil cleaner.
You really need to do these steps before consulting an HVAC dude.
If you suspect your cold control is staying on way too long just dunk the probe in some ice water. It should imediately shut down the compressor. If it don't then you needs a new control.

[Azhar]

check the thermostat and defrost timer if the ice covered all the evaporator pipes ,but if partly this mean leak in the refrigerator , if you want more explain my email: azherabc@yahoo.com

[SublimeMasterJW]

Place a piece of card board over the evaporator portion of your window unit and let it run about 10 minutes. If frost goes all the way back to the compressor then the unit has plenty of freon in it. That can mean only one thing.Your evaporator is stopped up. Clean it so the air can freely flow through those coils.

[SublimeMasterJW]

As the freon travels through the coils the air MUST flow at the designed rate. If the air is impeded in any way then the formula is lost and the result will be poor performance. The R-22 freon MUST have a 68.5 PSI suction on the low side to produce 40 degrees F across that coil AND the amount of room air that travels through that coil must meet the designed spec OR the freon will puddle up along the evaporator coil and form a thin layer of ice. Any slime,dust, or hair that can hold moisture will then be frozen over, The result will be a slab of ice forming over the evaporator coil.
Scenario 2:If the thermostat fails to shut down and the ambient temperature outside drops in the middle of the night then Icing will occur and another slab of ice will form. Their is NO defrost in the unit because it is NOT designed to defrost itself. It is designed to shut down when the temperature is reached. If it fails to do so then the thermostat needs to be replaced.

[icehouse]

You are correct in stating that this happens due to the outside air.
Years ago 1970's when I worked for Fedders we installed a low ambient control which sensed the outside air temperature as well as the coil's.
When the outside temperature dropped or the coil started icing, this control turned

the unit off until a warm-up occurred.

[Zanshin]

Depending on the age of the unit, you might be looking at a bad blower motor, not enough air flow across the evaporator will cause icing, along with a low charge of refrigerant and a dirty air filter and evaporator, they do make a spray on coil cleaner you can use to clean periodically. I think everyone else has mentioned the more common faults, wanted to be sure to cover all the bases