AC is not cooling

Michael Civisca · 06-21-2011, 07:01 PM

Our upstairs AC system (about 25 years old) is in the attic. It cools the second floor (we all also have a 1 year old system down stairs which is working fine). I just noticed the AC condenser fan is blowing cool air outside. I went upstairs and found it very humid. Obviously something is not working. For the first time I saw frost on the suction line where normally I see condensation (there is a 1" section of the suction tube that is not insulated that I used as a visual indicator). I believe I hear a slight hissing sound in the evaporator coil area above the furnace, and when I turned off the second floor thermostat, that noise slowing died away. The blower did not seem to be working at all, even after letting the system stay off for 15 minutes and switching the thermostat back on.

Before I call service, I was wondering what this may sound like?

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**JB Thompson** · 06-21-2011, 07:21 PM

could be several things, but first guess is low on freon

you haven't noticed it making that same sound on a regular basis? does your other unit make the same sound?

**Bruce King** · 06-21-2011, 08:20 PM

Originally Posted by Michael Civisca

Our upstairs AC system (about 25 years old) is in the attic. It cools the second floor (we all also have a 1 year old system down stairs which is working fine). I just noticed the AC condenser fan is blowing cool air outside. I went upstairs and found it very humid. Obviously something is not working. For the first time I saw frost on the suction line where normally I see condensation (there is a 1" section of the suction tube that is not insulated that I used as a visual indicator). I believe I hear a slight hissing sound in the evaporator coil area above the furnace, and when I turned off the second floor thermostat, that noise slowing died away. The blower did not seem to be working at all, even after letting the system stay off for 15 minutes and switching the thermostat back on.

Before I call service, I was wondering what this may sound like?

Since you indicated the indoor blower did not seem to be working, the frost would be a normal item with a broken fan capacitor or fan motor in the indoor unit.

**JB Thompson** · 06-21-2011, 08:24 PM

Originally Posted by Bruce King

Since you indicated the indoor blower did not seem to be working, the frost would be a normal item with a broken fan capacitor or fan motor in the indoor unit.

oops, I missed the part about the no-blow blower

**Rod Butler** · 06-22-2011, 12:11 PM

Turn fan to off.

Replace blower filter.

Let ice melt.

Turn system on.

**Scott Patterson** · 06-22-2011, 02:03 PM

Originally Posted by Michael Civisca

Our upstairs AC system (about 25 years old) is in the attic. It cools the second floor (we all also have a 1 year old system down stairs which is working fine). I just noticed the AC condenser fan is blowing cool air outside. I went upstairs and found it very humid. Obviously something is not working. For the first time I saw frost on the suction line where normally I see condensation (there is a 1" section of the suction tube that is not insulated that I used as a visual indicator). I believe I hear a slight hissing sound in the evaporator coil area above the furnace, and when I turned off the second floor thermostat, that noise slowing died away. The blower did not seem to be working at all, even after letting the system stay off for 15 minutes and switching the thermostat back on.

Before I call service, I was wondering what this may sound like?

At 25 years it has had a good life. The hissing sound could be caused by several things, most likely it was a leak if the sound has stopped. You will notice a marked savings on the energy bill with a new unit. Sounds like it might be time to sleep downstairs untill the replacement is complete.

Michael Civisca · 06-22-2011, 08:44 PM

Thank you gentlemen, your posts were helpful. I found the system was 31 years old, the exchanger is rusted and mostly likely showing some cracking. Rather than just replace the blower fan, we will go with all new HVAC system. And yes, we are sleeping in the family room for a week.