air handler coils froze up - question

[Soundguy]

was out working in the yard today. wife called me in.. ac not cooling.

quick check.. drastically reduced air flow at the vents...controls set right, compressor running like normal.. no noises or ratteling.. cooling fan going.. inside garage, air handle sounds like fan is running fine.. pull filter.. WOW clogged.. we just started running the ac here in fl this month.. must have sucked up all the dust in the house.

Ok.. I'm no AC engineer.. but I know the physics.. plugged air filter reduced the air flow, and the coils were able to frost over, further reducing air flow.

I checked drain tube, it's open.. so.. at this point.. I turned off the ac and air handler breaker, and as far as I know.. I just let everything melt while I'm at work tonight.. then when i get home, make sure all the ice is gone and the water DID drain down the drain tube, and then button back up and go on my merry way with some cold ac tonight?

my missing anything?

thanks

soundguy

 

[mustangsallysdad]

was out working in the yard today. wife called me in.. ac not cooling.

quick check.. drastically reduced air flow at the vents...controls set right, compressor running like normal.. no noises or ratteling.. cooling fan going.. inside garage, air handle sounds like fan is running fine.. pull filter.. WOW clogged.. we just started running the ac here in fl this month.. must have sucked up all the dust in the house.

Ok.. I'm no AC engineer.. but I know the physics.. plugged air filter reduced the air flow, and the coils were able to frost over, further reducing air flow.

I checked drain tube, it's open.. so.. at this point.. I turned off the ac and air handler breaker, and as far as I know.. I just let everything melt while I'm at work tonight.. then when i get home, make sure all the ice is gone and the water DID drain down the drain tube, and then button back up and go on my merry way with some cold ac tonight?

my missing anything?

thanks

soundguy

I think you are going to find that you are low on refridgerant or have a defective pressure switch.

 

[Bird]

Yep, that's usually a result of low refrigerant, so the next question is how low and why. However, if the filter stopped the air flow enough, maybe you'll be lucky and that's all. As for the condensation drain, some folks in the HVAC business say you should pour a little bit (maybe a cup of less) of household bleach in it a couple of times each season. I actually do it once a month myself.

 

[Soundguy]

comp sounded like it was running ok.. not kicking in and out. had a fan capacitor replaced outside late last year.. say september, refridgerant was ok then.. but I'll keep an eye on it.

if it ices up again I'll call the ac man out.

I'm hoping it was just the plugged filter.

And I do mean plugged! couldn't see light thru it. I must have forgot to change the ac filter at the end of last season before I started it up this year. ( we don't need to use the heat during the winter here in florida.. so it hardly ran since last year. )

crossing my fingers.

soundguy

 

[Willl]

Reduced air flow will definitely cause an ice up.

I bet you got it with your filter change.

 

[dex3361]

Probably just the dirty filter. A dirty filter will frost off the A coils as you described. Low gas will as well but since you found a very dirty filter I would go with that. Watch it fro a few days if it low on gas it will do it again in a few days if not sooner.

 

[Soundguy]

when I get home tonight I'll put the coil cover and fan cover back on and turn her on.. I'll monitor the air flow to see if it tapers off again.. and if so I'll pull the cover to check for ice up.. if it does it again/.. I'll call the ac man.

thanks for the advice guys.

My fault on the filter... I shoulda remembered to change it at the end of last season...

soundguy

 

[BobRip]

If you stop the compressor, but leave the fan running it will defrost much quicker. Of course some of that ice will evaporate into the room. Still it will defrost quickly.

 

[Soundguy]

i had to leave to go to work for 6hrs... so I left it open.. it's in the garage in florida.. I'm sure it will be defrosted when I get home tonight.

however, thanks for the tip. I'll remember that if it ever happens again ( hope not ).

again.. thanks to all.

soundguy

 

[buckeyefarmer]

clogged / dirt filter will cause the coil to freeze up. Been there done that.

 

[Soundguy]

well.. mine was clogged and dirty...

crossoing my fingers that's that all it was.. gross neglect

soundguy

 

[kenmac]

Reduced air flow. ie stopped up filter ,dirty evap coil or low refrigerant charge are just some of the reasons evap coil will freeze up. If your return is the correct size. then, it's probably 1 of the reasons that I listed

 

[Soundguy]

Just got home, buttoned it all back up with a clean filter, dumped some bleach down the drain line like someone sugested, though I know it's open and does flow.

fired it all up.. got cold air flowing.. pump doesn't seem to be cycling off and on fast like a car ac will when low on freon.

am going to check it every couple hours tonight to see if the air flow stops from freezing up again.

will post back int he am.

thanks

soundguy

 

[irvingj]

Sounds like you got it, Soundguy. Ditto the suggestion about leaving fan on with compressor off for defrosting.

 

[kenmac]

home ac compressors won't usually cycle on / off like auto compressors. If it has a low pressure switch it will usually stay off

 

[Bird]

home ac compressors won't usually cycle on / off like auto compressors. If it has a low pressure switch it will usually stay off

I guess my old Rheem didn't have a low pressure switch. The compressor just ran continuously when the coils were iced up and there was almost no refrigerant in the system. So of course, I had a new system installed a couple of weeks ago.

 

[Soundguy]

home ac compressors won't usually cycle on / off like auto compressors. If it has a low pressure switch it will usually stay off

good to know.

well.. I sett he ac for 76' and ran it last night from midnight to 7am.. ran fine all night.

got up a few times in the middle of the night for the call of nature and had good air flow entire time, including upon getting up this am...

figured i doged a bullet.

thanks
for the edvice everyone.


soundguy

 

[grunewald]

Reduced air flow is usually the number 1 cause for icing the coil. Now that you have it running, use a thermometer to check the return air temp. at filter or grill, then check supply air temp. in defuser blowing cold air into room. Temp. difference should be approximately 18 F. If you have 18 F difference,( this is ideal temp. difference) your unit is working good. If greater than 18 F, low air flow, if lower than 18 F, low on refrigerant or other problem. Didnt learn this at a Holiday Inn Express, been in the trade for 37 years.

 

[Soundguy]

I've seen that test.. the service guy here last year that repalced the cap on the external cooling fan did it.

good to know.

soundguy

 

[Bird]

Reduced air flow is usually the number 1 cause for icing the coil. Now that you have it running, use a thermometer to check the return air temp. at filter or grill, then check supply air temp. in defuser blowing cold air into room. Temp. difference should be approximately 18 F. If you have 18 F difference,( this is ideal temp. difference) your unit is working good. If greater than 18 F, low air flow, if lower than 18 F, low on refrigerant or other problem. Didnt learn this at a Holiday Inn Express, been in the trade for 37 years.

I have an analog pocket thermometer for checking cooling systems, and I have a multi-meter with a temperature probe that's even more accurate, but you have to get up to the outlets in the ceiling to use those, so I bought a new toy last week at Home Depot; a Ryobi IR001 non-contact, laser aimed, digital infrared thermometer.:laughing: It's a pretty neat little toy for $29.97 plus tax.