DannyW
Senior Member
Does the condensate drain have a float switch that shuts the unit off if the condensate is not draining?
I found out the hard way this is the first thing to check. Since my air handling unit is in my garage the float switch is dangling free so it cannot shut off my AC.
Pour some vinegar every now & then in your drain line to keep it clear of algae which can cause condensate to back up.
I agree with your maintenance suggestion, and even thought of this being a possible cause of the OP's problem. But I dismissed this as a possible cause when the OP said the outside fan was still running and blowing cool air. When the condensation pump quits or is clogged, it shuts off power to the outside unit. Or at least it does with mine.
I have a problem with my condensation drainage lines on the upstairs system. They clog up sometimes and I have to vacuum the water out of the drain line. While I am vacuuming out the water from the outside drain pipe, it reaches a point where the float resets and the outside unit kicks back on. (I know because I'm standing next to it.)
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