Central Air Conditioner Randomly Stops blowing cold air

by Jason
(Baton Rouge, LA)

Central ac unit Installed 4-3-2009

Central ac unit Installed 4-3-2009

1.25 year old RUUD 4-ton Condensing unit (3-phase)with Air Handler (UANL-048JAZ); 410a refrigerant.

When I come home and turn the thermostat down, the air handling unit in the attic will make a buzzing noise. When it makes this noise the unit blows air, just not cool air. The low end coming off the compressor turns dry and warm.

I can turn the central air conditioner off and restart it ~15 minutes later; the air handling unit will make a high pitched sound, as it does every time it is going to work, and it blows cold air. this may not happen again for 2 months or 2 weeks or 2 days.

Several Hvac techs have tried and failed to diagnose the problem; however, I have the central air conditioning unit working by the time they arrive. Please help, I have an 8 month and a 2 year old little girls in the house in Baton Rouge, LA (HOTTEST PLACE ON EARTH).

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Observe The Heat Pump Unit
by: Dadan

I'm guessing this is 13 seer Heat Pump units.

This Heat Pump unit is only 1.25 year. The best option is to called the contractor, who installed.

Here is two thing you could help the techs with. You need to observe the compressor and outdoor fan.

Observe the outdoor fan

Whenever, you're not getting cool air. Go where the condenser unit is at and see if the outside fan running. If the outside fan is running, it working fine.

Observe the compressor

There should be two copper line going to the house. You should see the insulated and big copper line and small bare copper line. ( they should be 5 or 6 inches away from each other.)

The big insulated copper line should be cold. Put your hand on it and see if it cold. The small bare copper line should be hot, so put your hand on it and see if it hot or cold.

Heat Pump will operate as regular central air conditioning unit in the summer. However, in the winter. It is reverse.

You're the best person to troubleshooting the heat pump units. You have to listen, smell and look and write it down if you have to. The next time you see the techs, tell him what you know.

Good luck,


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