After cooling a couple of degrees, AC runs but doesn't cool

Old 08-31-09, 03:24 PM
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Question After cooling a couple of degrees, AC runs but doesn't cool

I have a Trane XE 800 A/C with a new filter. When I turn on air initially, I get good air flow. When the temp has dropped a couple of degrees, the air flow reduces. Condensation starts to appear outside the plenum walls and the insulated pipe. Peeping through the humidifier hole I can see ice forming on the evaporator coils. The only way to shut the system is by turning it off at the thermostat. The contactor is NOT stuck, and is freely movable by hand. When open it shows no continuity, and in the closed position, it shows 0 resistance across both the low voltage and the high voltage sides, tested separately. The capacitors are not swollen or leaking.

I also tried checking out the thermostat. I tried reducing the temp in steps, one degree at a time. The a/c runs and cools. It doesn't shut off immediately when the control temp is reached but it does shut. It is when it has tried cooling for a couple of degrees does the efficiency go down and the air flow reduces. The a/c keeps running even when it is down to the control temp. Any ideas on what might be wrong?
Old 08-31-09, 07:02 PM
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It can be a few things.

-Dirty coil inside the home.
-Dirty coil on the outdoor unit
-Low on charge

My guts is heading towards low on charge.
Old 09-01-09, 01:10 AM
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Check the filter - if it's clean, call for service. You might have a refrigerant leak.

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