Icing causing blockage of blower air

[TroyWDW]

Waking up this morning I noticed that the furnace blower fan was running continuously with very low air flow at the registers throughout the house.

The outside air temperature yesterday was a high of 96 °F (55% rel. humidity) and overnight it was a low of 72 °F (74% rel. humidity).

It appears that the A/C heat exchanger inside the furnace ducting has completely iced over causing a blockage on the outlet ducting of the blower fan. I've started letting the ice dam melt and there is at least a gallon of water so far.

The insulated refrigerant line leading into the heat exchanger had visible signs of ice on it. The outside compressor appears to operating normally and the cooling fins are clear of debris.

The A/C has been operating for about a month without any noticeable problems (I live in Michigan). Is there anything simple and obvious that may have caused this problem? Would low levels of refrigerant cause this behavior?

Troy

[hiltontech]

Check the two copper lines behind your outside unit, you will see two copper lines, the bigger one should be cold and wet while the smaller one should be warm but not hot.
Make sure your filter is clean, also, check to make sure that the coils are clean inside and out.
Your problem seems to be with one of the four as I said above.

Let us know how it turned out for you, have more questions let us know.

HiltonTech

[TroyWDW]

HT, thanks for the quick reply.

coils are clean inside and out
By "coils" you mean the cooling fins on the outside unit, right? Those are clean and I cleaned them more with soap, water and a plastic brush.

Th small copper line is warm.

The big copper line is cool but not wet. I assume this indicates that the compressor is not able to cool the refrigerant sufficiently to cause condensation of water from the air.

I measured the temperature of the air exiting the registers at various points in the house. I'm observing 64, 66, and 68 °F in the three different levels of the house. Are there any general guidelines of what the temperatures should be.

Troy

[Ed Imeduc]

You want to check the temp drop right there by the coil on the in --side and the out-- side of the air blow. A good drop is 18o to 20o over the inside coil . That coil also has to be clean. if the big copper line is not wet outside Id guess you can be a little low on freon. if everuthing else is ok

ED ;)

[hiltontech]

Troy, it sounds to me that your low on freon, have some one check your charge and make sure that the inside coils are clean, you should be ok want s add the freon, before adding though ask the tech to try and find the leak and repair it before charging.

HiltonTech

[TroyWDW]

Thanks for the guidance. I looked up our maintenance records and now realize that the A/C unit was serviced two years ago and had freon added. Losing the freon charge in 2 years seems a little quick.

Last time the service charge was $250. If the tech can't find any visible leaks, do you have any thoughts. I don't want to continue pouring money into a system that may be nearing the end of it's service life. The A/C unit is 15 years old. What's a typical service life.

Thanks again.

Troy

[hiltontech]

An a\c can last upwards up to 25 years, I know this because I've i've worked on them,in fact I have two of them where I work that are 24 years old, but in most cases anywhere from 12-16 but ask another tech and he may give you a different answer.
It is possible it's leaking from both inside and outside units, if you only lost a small amount of freon then you can add some and it may hold you for another 2 years (if your unit holds up) but I wouldn't put hard earned money into it being it's 15 years old, instead I would buy a new unit inside and out, it's your call.

Good Luck


Hiltontech