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Why is my air conditioner blowing warm air?

The thermostat is set at 75 degrees and is reading over 80. Could that cause the problem? It is 100 degrees outside. My husband says I broke it by setting the thermostat at 75 and is throwing his usual tantrum. Is it true that setting the thermostat at 75 degrees when it is 100 degrees outside that it would break the air conditioner? It needed Freon 2 years ago. Is it normal to have to periodically replace the Freon? It went out a week ago and then came back on in a few hours (after being temporarily turned off). This is Tucson, Arizona. Hot! Mr. Tantrum said it was probably frozen. What is the cost of fixing this problem? What is the best way to prevent this from happening in the future?

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1 Answer from this member:
Joey S
You did not indicate if this is window air conditioner or a central air conditioner, but my answer holds true to both.

Your husband is most likely correct in saying that the air conditioner was "probably frozen". This can be caused by

setting the thermostat too cold, a dirty air filter, short on Freon or dirty evaporator coils

. If the air conditioner is sized too small it can cause the compressor to run continuously too and cause the evaporator coils to ice over and stop cooling.

By setting the thermostat to 75 degrees is not going to make it cool any faster. It could cause the compressor to run constantly and can cause the evaporator coils to ice over and then start blowing warm air. Most likely the room temperature would never reach 75 degrees even with a correct working air conditioner when the outside temperature is 100 degrees. There are many factors involve, how well the house is insulated, how many windows, direct sun light, etc.

The air conditioner could also be

short on Freon

again too. Freon should never have to be added unless it has a slow leak and it never has to be replaced. If the air conditioner is short of Freon it can cause the unit to ice up and start blowing warm air.

The cost of repair would depend on what the technician finds wrong. I recommend setting the thermostat a little bit warmer so the compressor can cycle off and on and set the fan speed on high. By increasing the fan speed could prevent the evaporator coils from freezing over.

If the air filter is clean and you raised the temperature some and it still freezes up, I recommend calling a service technician to diagnose and repair your air conditioner.
by Joey S Earned 7,438 community points in Building Supplies
July 16th, 2008
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