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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My Central Air evap coil is freezing , preventing airflow.

Customer Question

My Central Air evap coil is freezing , preventing airflow. Evap coil, condse coil, duct and filter have all been thoroughly cleaned. Unit has recently (5 days ago) been charged. Service tech , said it was freezing because it was low on coolant , and there
must be a leak . He thought the leak must be very small as he couldn't find it ,and decided to charge the unit and see how long it would take to stop working .??? something seems wrong with this process? Also , doesn't address the freezing issue . The unit
freezes in about 30 to 40 minute time frame , up until that point , the air out is running about a 25 degree delta from the air in .
Submitted: 2 years ago.
Category: HVAC
Expert:  airheatman replied 2 years ago.
If air flow is good across coil, low refrigerant is most likely cause.If unit has leaked back down in 5 days the leak should be large enough to find.Leak searching can become involved as it could be at indoor coil ,outdoor unit or anywhere in between in the copper tubing.At this point, first step is to verify if charge is indeed low again and if so, spend the necessary time to trace the leaks and repair or replace as needed.
Customer: replied 2 years ago.
Can moisture in the line cause this ?
Expert:  airheatman replied 2 years ago.
No the only three things that cause icing is low on charge, a restriction or outdoor unit running while inside unit is not moving enough air across coil.Since you had a 25 delta T I do not expect a restriction.

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