Just another theory, that happened to me during outtage. I had double whammy, 1st being a smart thermostat that forgot settings (internal backup battery died). It wasnt turning my blower on. 2nd was that during initial cooling of the house, the moisture/humidity in house and eventually clogged condensate drain triggered my condensate pan's overflow kill float switch. The float switch then once again caused the entire system to not have power, which in turn caused my 1st problem again, dead smart thermostat. I don't have a C wire and actually wired one in, but the smart thermostat didn't like it, so I removed it and went back to my previous setup.

Resolved by cleaning my condensate drain (vinegar, shop vac, chasing it), drying up the pan, manually charging smart thermostat via USB, and resetting the settings in the thermostat based on my wiring.

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Posted by gumbo2176

Member since May 2018

15096 posts

Posted on 9/16/21 at 10:26 am to Schmelly

quote:
Soooo, I turned it off completely when I went to bed last night

I'm going with the coil being frozen over on this one and your leaving the unit off all that time let the ice covering it thaw and open the coils so the air can now pass over them, especially when you said your vents were only putting out a faint air flow.

I had this happen once to my old unit I eventually replaced 2 years ago and I opened the unit to get to the coils, saw there was a lot of ice built up on them and used a hair dryer to melt it.

Then I took an old nylon bristle brush and cleaned the coils the best I could since they did have a bit of dirt on the fins and after putting it all back together again, it worked fine until I replaced the unit several months later.

If it happens again, open the unit to gain access to the coils and I'd bet dollars to donuts it's iced over. Then do the above procedure to get it to working again.

This post was edited on 9/16/21 at 10:31 am

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Posted by junkfunky

Member since Jan 2011

33890 posts

Posted on 9/16/21 at 12:04 pm to gumbo2176

quote:
Then I took an old nylon bristle brush and cleaned the coils the best I could since they did have a bit of dirt on the fins and after putting it all back together again, it worked fine until I replaced the unit several months later.

They make a foaming spray specifically for coils that washes away as the coils condensate. The only way I can get to the intake side of the coils is to climb the return chase. So much easier to just spray that stuff than trying to brush the fins and bending most of them.

I did that about 3 years ago and haven't had any problems with freezing coils since.

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Posted by Schmelly

Member since Jan 2014

14469 posts

Posted on 9/16/21 at 10:45 pm to gumbo2176

My only question would be, “how was it frozen up to begin with?” It was shutdown for 5-6 hours while the power was out.

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Posted by CrawDude

Baton Rouge

Member since Apr 2019

5266 posts

Posted on 9/17/21 at 10:24 am to Schmelly

quote:
My only question would be, “how was it frozen up to begin with?” It was shutdown for 5-6 hours while the power was out.

Most common causes of a evaporator coil freezing over is (1) poor/low air flow - causes include restricted/dirty air filter, air handler/furnace blower motor not working properly, dirty evaporator coil (2) HVAC low on refrigerant. If the unit is over 6 years old, often from a leak in the evaporator coil which is notorious for leaking with age.

This is the upside of having a HVAC tech come out once or twice a year to provide maintenance service on the HVAC. They clean the outside and inside coils, clean the condensate drain, check refrigerant pressure, superheat/subcool to see if unit is charged within manufacturer’s specs, check amperage draw on motors, etc.

This post was edited on 9/17/21 at 12:30 pm

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Posted by keakar

Member since Jan 2017

30001 posts

Posted on 9/18/21 at 3:33 pm to Schmelly

quote:
I’m crazy. It’s blowing out. But it’s not much and not very cool. Had to get really close to it to tell

that sounds like the plenum box has fallen off the unit and its not sealed so all the air is just escaping into the attic

time to go in the attic and see where the air is going unless its frozen solid with ice from a leak

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