1kris06
1kris06 HalfDork
6/1/20 9:02 p.m.

Came home to the house warm and 76* when the ac is set to 70*. I had the ac off and Windows open for a couple hours the day before. AC was working fine when I left for work today.

 

Why does my cold (I think this is what it is) coil keep freezing up. Only seems to happen after I've had the ac off and the windows open previously. I also had the basement vents closed (to try and keep the main floor colder) since no one is down there.

 

Any help would be appreciated.

lotusseven7 (Forum Supporter)
lotusseven7 (Forum Supporter) Reader
6/1/20 9:31 p.m.

Can't help specifically, but every time I've had issues with either the heat or AC in the house, it had to do with the condensate drain. It gets plugged up with sludge in the summer or the line freezes in the winter.

 

Check the drain is all I've got for you.

Purple Frog (Forum Supporter)
Purple Frog (Forum Supporter) Reader
6/1/20 9:45 p.m.

Usually when it freezes like that you are low on freon.  A leak has developed in the system.  A tech can put a tracer in and find it... and hopefully be able to repair.    

Steve_Jones
Steve_Jones Reader
6/1/20 10:00 p.m.

Low on Freon. A charge might get you through another season if it's not bad, but that's what's happening. 

Toyman01 (Forum Supporter)
Toyman01 (Forum Supporter) MegaDork
6/1/20 10:01 p.m.

Agreed, low on refrigerant. Another possibility is low air flow. Have you changed the filters recently? If not, start there. 

 

 

11GTCS
11GTCS Reader
6/2/20 6:54 a.m.

X 2 on above, I would check the airflow first.   Check / replace your air filter first.   If you can, see if you can get a look at the air inlet side of the cooling coil as it can get covered with dirt and crud if the filters aren't maintained regularly.    Vacuum any dirt off and rinse the coil and drain pan with water.   

Shutting off all of the basement vents may be reducing the overall airflow, maybe partly close them instead of shutting them completely.   Finally, make sure the return air grille or grilles aren't blocked by furniture or debris.  What temp did you have the thermostat set for?  If you set the thermostat too low (usually 68 or lower) it's possible that the temperature at the coil has dropped to the point that instead of creating liquid condensate it's starting to freeze.   Once the coil face frosts up you go to zero airflow / no cooling.

spitfirebill
spitfirebill MegaDork
6/2/20 7:00 a.m.
Steve_Jones said:

Low on Freon. A charge might get you through another season if it's not bad, but that's what's happening. 

This is what we've been fighting for a couple of years.  Because it uses R-22, the recharges are expensive.  We have to make the decision when to replace the unit.  

mtn (Forum Supporter)
mtn (Forum Supporter) MegaDork
6/2/20 8:19 a.m.

As others have said,  you probably have a refrigerant leak. 

 

That being said, the first step to take is to turn the AC off, turn the fan on, run it for at least 12 hours (until the ice is melted off the coils). Your hope is that, as Toyman and 11GCTS said, that it is either dirty or not getting enough airflow. Spray the coils down with water and run the fan again until they're dry. Change the filter. Open up the vents in the basement, at least partially. This is all easy and free, and if it does happen to be the case, eliminates an expensive trip from an HVAC tech. 

 

I went through the same issue. Still going through it. This summer we're running window units, because I'm tired of throwing $$$ at recharges when it gets more and more expensive, and no one so far can find the leak. Will be in the budget for next summer.

jgrewe
jgrewe Reader
6/2/20 10:14 a.m.

If you are lucky your leak will be in one of the schrader valves.  They can change the bad core out without taking out the freon.

If you are REALLY lucky it is an airflow problem.

1kris06
1kris06 HalfDork
6/3/20 9:02 a.m.
mtn (Forum Supporter) said:

That being said, the first step to take is to turn the AC off, turn the fan on, run it for at least 12 hours (until the ice is melted off the coils). Your hope is that, as Toyman and 11GCTS said, that it is either dirty or not getting enough airflow. Spray the coils down with water and run the fan again until they're dry. Change the filter. Open up the vents in the basement, at least partially. This is all easy and free, and if it does happen to be the case, eliminates an expensive trip from an HVAC tech.

Replacing the filter and turning the ac off for 10 hours seems to have fixed it for the time being.

Thanks for the suggestions everyone

aircooled
aircooled MegaDork
6/3/20 10:10 a.m.
jgrewe said:

If you are lucky your leak will be in one of the schrader valves.  They can change the bad core out without taking out the freon...

I am curious how this would be done if you know.  Normally, removing a valve will open the entire system.

I would think the way they would do this would be to draw out the refrigerant, change the valve, then refill.

jgrewe
jgrewe Reader
6/3/20 10:29 a.m.
poopshovel again
poopshovel again MegaDork
6/3/20 10:36 a.m.

Low freon OR: Do you have pets? Our coil used to get covered with cat hair, and I'd have to clean the coil once a year.

z31maniac
z31maniac MegaDork
6/3/20 10:41 a.m.
1kris06 said:
mtn (Forum Supporter) said:

That being said, the first step to take is to turn the AC off, turn the fan on, run it for at least 12 hours (until the ice is melted off the coils). Your hope is that, as Toyman and 11GCTS said, that it is either dirty or not getting enough airflow. Spray the coils down with water and run the fan again until they're dry. Change the filter. Open up the vents in the basement, at least partially. This is all easy and free, and if it does happen to be the case, eliminates an expensive trip from an HVAC tech.

Replacing the filter and turning the ac off for 10 hours seems to have fixed it for the time being.

Thanks for the suggestions everyone

At a minimum, you should be changing the filters every 3 months. 

We change them every month, or at least try to remember to, because we have pets and damn if OKC isn't windy as hell that puts a ton of dirt/dust/grit in the air non-stop. 

The wind is so strong and pervasive, it pushes the super fine dust through window seals to settle on the sills. 

As in, it pushes so much dust through, after living here 6 months I called Terminix to check for termites. 

NOT A TA
NOT A TA SuperDork
6/3/20 10:45 a.m.

In reply to 1kris06 :

The evaporator in the air handler may be plugged up also and if so will ice up. Have you ever cleaned the evaporator or had it cleaned?

That said, if the system has certain types of air ducts, they break down over time. If you notice more light colored dust in the house during AC season the ducts may be breaking down. If so, the dust from the return ducts sticks to the condensation on the evaporator clogging it up which then causes it to ice up.

aircooled
aircooled MegaDork
6/3/20 10:57 a.m.
jgrewe said:

There is a special tool that goes on the valve.  It unscrews the core and pulls it out as you close the quarter turn valve.

Wow, interesting, I had no idea that existed, thanks.

1kris06
1kris06 HalfDork
6/3/20 7:13 p.m.
NOT A TA said:

In reply to 1kris06 :

The evaporator in the air handler may be plugged up also and if so will ice up. Have you ever cleaned the evaporator or had it cleaned?

That said, if the system has certain types of air ducts, they break down over time. If you notice more light colored dust in the house during AC season the ducts may be breaking down. If so, the dust from the return ducts sticks to the condensation on the evaporator clogging it up which then causes it to ice up.

It's a friend of a friends place. He's been gone the past 3 months because of the covid stuff. It's only happened 2 or 3 times since I've been living there. And everytime is after I've shut it off and had windows open. Short term solution is to up the temp if I want to open windows and always leave the unit switched to AC and on.

Grizz
Grizz UberDork
6/3/20 7:30 p.m.

Take a hose to the outdoor coils. Don't full blast them cause you'll bend them but a decent spray, look down into the unit to see if water is coming through. Do the entire coil with a slowish up and down.

Nobody cleans them ever and they suck up just as much E36 M3 as the indoor coil and if it can't pull air through it's going the freeze.

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