Central air icing up

[diplomat 1]

So I come and see the thermostat is at 72 when the central air is set at 70 went to check and see this

https://s32.postimg.org/gl1r9c7c5/image.jpg
https://s32.postimg.org/ds8jpb6zp/image.jpg

The motor spins the fan but no air is going thru to the vents. How does it ice up like this? What are my options? 2 months back I had someone refill the system with refrigerant and had the pressures balanced and it has worked fine since then. Any ideas on how to fix? Thanks

 

[Weird Tolkienish Figure]

Mine did this, cleaned filter and it didn't do it any more. THey need to be cleaned more than you might think.

 

[Rockhead261]

Poor airflow (loose belt, dirty blower/filter, blocked return)

Undercharged. You had refrigerant added before; could be a leak.

Restricted metering device/moisture in the system.

Turn off the a/c and run the fan until the coil thaws. Take it from there.

Sent from my SM-G930V using Tapatalk

 

[brewchief]

You either have an airflow problem such as a dirty filter or you are low on refrigerant, since it sounds like it was low earlier in the season i would bet it's low again and you have a decent sized leak.

Sent from my XT1254 using Tapatalk

 

[1320stang]

We used to have a similar problem, the A-coil would freeze up. The coil was dirty so I bought some spray that helps clean it off. The thing that has helped the most is changing the fan from auto to on. There's always air flowing across the coil and it doesn't have as much of a chance to freeze up.

 

[Richard Cranium]

like all has said all ready, either a air flow problem or low on Freon.

 

[Rory Bellows]

new air filter is needed. Turn it off let it thaw out and put a new filter or clean the filter and you should be good.

 

[TractorJeff]

That belt looks really low on the pulley! That is an old one speed system, I'll bet!
My whole heating/cooling system was in really bad shape when I bought our house. The A coil was plugged with dirt because the electro-static air filter had quit a LONG LONG time ago. I cut a hole in the sheet metal and got in there with a nylon brush and compressed air blow gun and a shop vacuum. This improved the heating somewhat but the fan was still slow. A buddy changed out a similar brand furnace and I got his 4 speed motor with a fan around it. I installed that and set it to run on speed two 10 years ago. So far I have been lucky but I push the wife to not go much below 74 as it runs too much and I often think it could freeze up like that!

 

[Dagny]

If it was low on refrigerant the frost would not be that even. air flow.

 

[epmills]

If it was low on refrigerant the frost would not be that even. air flow.

X2. Turn off the a/c and just run the fan as previously suggested until it is thawed. Once it thaws take a look at the other side of the coil, a unit that old probably has a decent amount of build up blocking air flow. Filters don't catch everything...

 

[pop pop]

Well, if the system needed refrigerant, it has a leak. Your guy didn't fix the leak, so now it needs more refrigerant. If the leak isn't repaired, it will need more refrigerant.

 

[Wakefield]

If it was low on refrigerant the frost would not be that even. air flow.

Won't sweat or ice all of the way to the end of the run.

 

[JerryC]

Looks like the fan blades are a little dirty, could mean the coil is dirty as well.

 

[crabjoe]

I'm going with the low refrigerant group, based on you needing a fill before..

If there's no leak, you should never need to add refrigerant.. it's a sealed system.

Take some soapy water and see if you have a leak at your valves... Last couple of friends that needed a fill, only ended up needing new schrader valves to stop the leak.

 

[md21722]

I had a bad cycling switch cause this once. Otherwise low refrigerant.

 

[acmikee]

start with the easy stuff
is the filter clean
is the coil clean
is the belt tight
fan clean and turning in the right direction

now your a/c needed refrigerant 2 months ago did he fix or even look for a leak. if not guess you still have a leak. get if fix...problem solved

 

[TractorJeff]

Thought about this last night; can anyone explain to me why low refrigerant causes icing?
I would assume it would expand itself prematurely, expending its cooling capacity early thus not cooling enough? Or is it a pressure issue verses a volume issue?
Guess I just don't understand an AC system well enough?

 

[bazar01]

Thought about this last night; can anyone explain to me why low refrigerant causes icing?
I would assume it would expand itself prematurely, expending its cooling capacity early thus not cooling enough? Or is it a pressure issue verses a volume issue?
Guess I just don't understand an AC system well enough?

It's all about the refrigerant pressure/temperature relationship.
Low charge results in a low suction pressure thus low saturation temperature below 32F. Then moisture in the air condenses and freezes on the cold evaporator surfaces and suction line.

 

[joel63]

It's all about the refrigerant pressure/temperature relationship.
Low charge results in a low suction pressure thus low saturation temperature below 32F. Then moisture in the air condenses and freezes on the cold evaporator surfaces and suction line.

^^^^^ Exactly.

And the longer the unit run under that condition, the more the ice will develop.

I've seen ice on the suction line all the way back to the compressor.

In one case, I saw half of the compressor shell covered with a 1/2 inch coating of ice.

The unit kept running because the lady of the house was warm, so she pushed the thermostat down to 65°.

Took a long time to defrost that one.