Lennox Central Air Conditioner Help needed

Old 06-30-08, 06:24 PM
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Exclamation Lennox Central Air Conditioner Help needed

The hot summer has come and as of today my central air conditioner no longer cools my house.

There is a small amount (very small, weak) of air that comes out of the vents around the house. It isn't cool air, it is room temperature air.

One of the two pipes which lead from my furnace to the outside air conditioner has condensation forming on the insulation. The non insulated, thinner, pipe is cold. The insulated pipe has the condensation forming outside the insulation. I haven't peeled the insulation away, but I assume the insulated pipe is supposed to contain the hot water that the air conditioner removes from the house.

At the base of the insulated pipe (as it inserts into the furnace) there is a clump if ice about the size of a golfball.

The outside air conditioning unit spins normally. There is no debris around the outside unit and the fins on the outside unit are clean.

The furnace is a Lennox and both the CAC and furnace are 4-5 years old.

I just removed the cover to expose the A coil

sure enough the entire A coil is frozen over.

I am going to let it defrost over night and then inspect if further.

Possibilities are:
1) lack of refridgerant
2) dirty A coil

anything else?

also, should I disconnect the two pipes (hot and cold) that connect to my A coil and then remove my A coil from the furnace housing in order to clean it?
Old 06-30-08, 06:34 PM
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Your unit is low in refrigerant. You should have it checked for leaks, have the leak(s) fixed and only then have the unit recharged.
Old 06-30-08, 07:14 PM
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how do you automatically know it is low on refridgerant if you dont mind my asking?

I am not saying that this isn't one of the possibilities

but why can't there be other possibilities too? if so, what are they? if not, why not?

Old 06-30-08, 07:16 PM
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Don't disconnect anything from the A coil, this would cause you conciderable physical pain. And then you would get the medical and HVAC bills, which of course would be a different kind of pain.

You need to call a tech for assistance with this.

But, just before you pick up the phone, check your air filter(s).
Old 06-30-08, 09:50 PM
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I believe it looks like low refrigerant because your liquid line (small line) was cold, whereas it would normally be warm to hot.

Additionally, as Jarredsdad mentioned, you can't touch the A/C lines. It is unlawful for non-certified persons to operate on sealed refrigerant side's of refrigeration systems.

Normally the evaporator coil (A Coil) get's cleaned without removal, by opening the plenum. This can be done diy style if the plenum is easily opened, as sometimes it is not.

The air filters need to be checked because a dirty air filter reduces air flow across your coil, and can freeze it up.

Good luck.
Old 07-01-08, 05:13 AM
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I agree too, low refrigerant is the number one suspect. Unless you know something you didn't tell us. Such as: someone not changing the filters on a regular basis, evaporator coil loaded with dirt that you cannot see the fins, blower motor not working correctly or shutting down while the condensing unit is still running or oversized system with ducts that are too small.
Old 07-01-08, 05:28 AM
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Air Conditioning Repair

Go to your thermostat there should be two switches one says heat-off-cool turn that to off the other will say something like fan on-auto turn that to on this will force your fan to run while turning your cooling off.
Your indoor coil is frozen this is why you have no airflow so when you put the thermostat in the position I described it will thaw out the coil in about two hours, then we need to figure out why it froze up.
First remove the filter if there is one if the filter is very dirty you may have fixed your own problem if not then you need to look for other loss of airfow possibilities such as blocked or closed off vents or a dirty coil.
If you have good airflow then someone may have turned the thermostat too low or you may have a problem with the refrigerant circuit either it is restricted or low on refrigerant when you turn it back on after thawing it out you will know if you have good airflow and it freezes up again that you have a refrigerant circuit problem.

In addition (I apologize I didn't read your last couple of sentences) don't disconnect anything!!! you should be able to carefully slide the coil out to look at the underneath side to clean without disconnecting anything.

Last edited by mike n; 07-01-08 at 05:56 AM. Reason: incomplete

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