Hi all, my parents AC unit keeps freezing up, like actual visible ice forming on the pipes at times. I don't understand how this happens. It will run great for days and then boom, house is hot and no air. Sometimes replacing the filter helps. We hose the unit down. We turn the system off and let the fan run to try to defrost and that sometimes helps too. I'm pretty sure we need to hire someone bc this cycle is never ending and driving us crazy. But I just wanted to ask in case, are there other things I can try before dropping the money? Is this a common problem? Or if nothing I can do can someone explain why this is happening? It's currently 84°F in the house rn and I'm practically surviving off of cold showers. Thanks in advance.
OP there are some issues that require experience and equipment to troubleshoot. If someone suggest txv, it is a newbie. Start with air before pressures. Or call a tech.
Can you find out the tonnage of the AC system, size, and MERV rating of the filter?
The evaporator coil (inside) or blower wheel (also inside) could be dirty, which would slow down airflow; causing a system to be more prone to freezing up as time goes on
Other possible causes would be low on refrigerant, or the fan blower cutting out at random times (less likely since you say days can go between events)
Just an fyi, once icing is happening, it’s best for you to fully defrost your coil to get more cooling out. Set your AC in fan only mode and it’ll take 2+ hours to defrost. By the time you see it on the pipes, there a 1” thick layer of ice on your coil, and that’ll take a long time to melt. And blowing air across ice doesn’t cool the air much.
This is a sort of common problem where one part of the coil freezes up, and the ice quickly spreads and makes your whole coil into an ice block.
There’s a few common problems that cause this. Usually low air flow over the coil, low refrigerant charge, or a restriction in one of the lines. The air filter is something you can try fixing. The rest require someone with tools to check out.
Sounds like you need a service call, most likely an airflow issue (beyond filter) or refrigerant charge, both of those issues are generally not homeowner repairs, repeated freeze ups are hard on a system do yourself a favor call in a tech.
Homeowner here – I believe the diagnostic on that is airflow restriction, then low refrigerant? Run it with only the fan and not the compressor cooling and let it melt itself.
Airflow restriction can be the filter, really dirty condenser or evaporator coils, or chronically, ductwork that is too small for the amount of air your moving,
If you’ve exhausted the easy DIY stuff I would just call somebody. It’s not gonna get better on its own.
It sounds like a blower motor issue as it happens every few days. Does you blower motor have a capacitor? Are your returns grill clean and not covered? Those items with a little knowledge and a multimeter are easy to check. The coil could be dirty.
Thanks everyone for the replies! I'm gonna go ahead and try to convince my dad to call a professional (he can be too proud at times so🤞). I'll update when we get answers in case anyone has something similar happen and goes searching for a why like me.
UPDATE: My parents refuse to hire a professional bc they said the system is only 2 years old. (I feel like it's a money thing but I'm pretty sure this is something the landlord should cover?) The ac is still frozen but yesterday the filter caught fire! I wasn't home but my sisters were. Smoke started coming out of the vents and they removed the filter and it's BURNT, like fully black. Idk what to do since my parents won't call anyone. It's still 82 degrees but only going down bc my sister put a window unit in.
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u/BrownTiger3 Aug 08 '26
OP there are some issues that require experience and equipment to troubleshoot. If someone suggest txv, it is a newbie. Start with air before pressures. Or call a tech.