Last night my wife was feeling hot and decided to turn the A/C thermostat all the way down (she didn’t tell me she was doing this and I didn’t realize until I woke up freezing my ass off). Tonight I noticed the A/C wasn’t really blowing out cool air and on inspection it appears that it has frozen up. Is this something that I can just let thaw over night, or do I need to call a repairman to look check out the unit?
Yes. I’ve done that many times.
Check your filter as insufficient air flow across the evaporator will cause icing. If the filter is clear, and this happens frequently, you may need to boost the fan speed, depending on the type of unit you have, this may be as simple as moving a link on the controller circuit board.
Thanks for the replys
I clean the filter about every other month so that shouldn’t be a problem. Again thanks for taking a load off my mind.
I assume we’re talking about a window unit.
Is it not blowing cold air, or not blowing any air. If there’s no air at all coming out, sounds like ice. You can pop the cover off and take a look. BTW if the filter is stuck to the coils, that’s a sign of ice, don’t pull on it, it’ll rip. Assuming that’s the case, yeah, let it thaw over night, or you can run the fan and that will speed it up quite a lot.
Call a service man.
Here are the causes of a unit freezing up (in the general order as to how common it is)
- Low on refrigerant. (Freon)
- Dirty filter
- Dirty coil
- Too may registers closed
- Blower intermittently not working (or not working at all)
- Some noob turning the thermostat all the way down
- Restriction in the ‘liquid line’, ‘starving evaporator’
You may notre that items 2-5 all speak to air flow; a critical part of an A/C system. If an A/C system runs for extended periods iced up it runs a very real chance of destroying the compressor outside. That repair is often $700-1200 on many residential systems. (and could be more) (I don’t think boosting the fan speed will be a factor, as almost all A/C systems are already set up for cooling to be on the highest speed)
We don’t have enough information to diagnose this, but running the stat “all the way down” could certainly cause a unit to ice up. Still, for the exact same reasons you wish your car to give you years of ‘repair free’ service, you should practice preventive maintenance. So, my recommendation is to call a service tech.
Like the old Fram Oil Filter commercial, “You can pay me now (a tune up on your A/C system will be around $100) or you can pay me later” (a new compressor will be around $1000)
ETA:
If it’s a window unit, don’t call a tech.
Wait and see if it ices up again. There is little that can be done to a window unit, and IMO it’s not worth the service call.
And, tell your wife it is not cool (pun intended) to run the stat all the way down.
If you run the A/C beyond what is needed to cool the room, then it would be unsurprising to find ice build up.
Let it thaw out thoroughly, then use it at a moderate setting and take note of how it performs.
Then you can call a repair service if we are all wrong. No reason to call one now when you have a gigundus variable to eliminate, and might as well eliminate that variable for free.
I would disagree with this.
Everyday I see systems that are working and cooling that are low on Freon, and have other ailments—and are simply waiting to fail.
It is 12:10 p.m. EST and I have an appointment at 2:00 p.m. to sell a man a new heat pump for $4800. The compressor failed, and the unit is old enough that it will make more sense to put a new system in. He had no maintenance done to the unit, and I suspect he could have got a few more years out of it. I regularly see units that need to be repaired or replaced due to neglect.
The problem with this advice is that the only qualification RetroVertigo has to “take note how it performs” is that is cools. That’s it. With that rationale, I suggest you never change your oil until the car won’t start, or check your tire pressure until they’re flat or obviously quite low.
One common scenario:
RetroVertigo’s unit is moderately low on freon, but not enough that it won’t cool. It runs longer than it should, but he doesn’t notice or pay attention. It raises his electric bill, but not enought to notice or alarm him—maybe $10-20 higher than it might be otherwise. So…it runs maybe 10,20 30% longer than it would if the charge were right. But the house is cool. Out of sight, out of mind. (a low freon charge will lower pressure and cause freezing if the pressure falls below 60 psi)
The problem, other than the fact that he is spending more on electric than he should, is that that freon cools the motor windings on the compressor. The next time he notices no cooling may be when the compressor fails—a very expensive proposition.
Until now, he hasn’t noticed or cared. But his wife lowered the setpoint, and brought the already low pressure (due to low freon) down further, and caused the unit to freeze up.
Pay attention: Preventive maintenance is unrelated to repairs. You don’t change the oil in your car because the engine seized, you change it because you hope to prevent it from happening.
Preventive maintenance is practiced to prevent failures/repairs.