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We've lived in our house for three summers and have never had any problems with the air conditioner. Today I noticed that there was ice on the coolant return line outside the house. I didn't think anything of it.

Later in the day (now), the system had shut off. Even though the temperature in the house was much higher than the thermostat setting, neither the air blower nor the fan in the AC unit outside was running.

I've read that the ice on the lines may mean that the system is low on coolant. Will simply having the coolant recharged fix the problem? Do I just need to wait for something to thaw?

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  • Ok, it looks like the iced-over line was a symptom, not the cause. The root of the problem seems to be that the fan is not spinning. I suppose the next steps for me would be to either call a professional or see if I can fix or replace the fan motor. Any thoughts on that?
    – coderj
    Commented Oct 11, 2010 at 1:58
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    How do you know the problem is the motor? How do you know the problem isn't the controller electronics in the outdoor unit? If you don't know what you are doing, call an HVAC person.
    – myron-semack
    Commented Oct 11, 2010 at 12:52

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ice usually means either your air handler isn't pushing enough air across the coil, or your system is out of refrigerant.

so first step is to set the cool/off switch to off. then set your fan switch to on. if the air handler fan does not turn on, then you have a problem with your air handler or thermostat. possibly cheap. possibly something you can fix yourself.

otherwise, you probably have a problem with refrigerant (which should not deplete, and if it does then you have a leak somewhere) or your compressor. in either case, you should leave your system off to avoid damaging your compressor until someone can come out and look at it.

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I would check airflow. Have you closed and air vents, is any furniture blocking vents, has any work been done to the ducts, is the filter dirty, is the evaporate coil dirty, is the blower wheel dirty, is the blower spinning at the right speed. Once those things have been confirmed, THEN you check your refrigerant. 70% of the service calls for iced evaporators are from dirty filters/ restricted airflow AND/OR low on charge. Also check for any restrictions in the liquid line (small copper) such as a pinch or Kink. Feel if the line is hot before the kink and cool after. Service and Maintenance are generally based on how good your observations are.

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A frozen suction line is generally more indicative of poor evaporator coil airflow rather than being low on charge.

Before you jump into checking pressures or troubleshooting the furnace/condenser controls, check to make sure your furnace fan is providing proper airflow, the filter is clean and the coil(s) are clean.

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This is a long shot but check your electrical panel and make sure the circuit breaker for the air conditioner is not tripped. I think the air conditioner unit will be on its own circuit separate from the blower that circulates air throughout your house (at least that is how it is set up in my house). If the air conditioner circuit is tripped, then the AC unit will not go on but still you will be hearing your blower and think everything is working.

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    Your assumption is correct - the condenser unit is powered separate from the air handler. There is normally a fused disconnect outside for the condenser fed from a its own breaker from the main panel. However, if the condensing unit lost power (either breaker trip or fuse(s) blown) you won't get the symptoms OP described (icing).
    – kkeilman
    Commented Oct 12, 2010 at 18:58
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My problem was a bad run capacitor for the blower, With the air handling unit fan (blower) not running properly this caused my suction line to freeze up.

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