Hi folks,
This is my first summer after moving into this house. The A/C is running okay but has one problem, everytime after 40 min of running, the ice starts building up on the evaporator coil and spreading to the law pressure hose. I have checked the air flow, not much of restriction. The blower motor runs fine, it can run for hours with a good speed without problem. I used an app to measure the wind speed at the register, it runs at 9 m/sec for hours without A/C on. However, if the A/C cooling is on, it runs for good speed for 40 min then the wind speed start reducing coincide the ice forming. The temperature at the register goes from 70 degree F when A/C kicked in, and stayed at 70 for 35 min, then starts slowly going up from 70 to 74 and stays there unless ice was melt. I don't know what could cause this, low refrigerant? I live in south of Ohio, summer here is around 90F.
The heating/blower system made by Williamson and the A/C compressor by Ducane. The A/C compressor and evaporator coil looks like new or close to new.
Please help me troubleshoot.
Many thanks,
Frank

 

Welcome to the forums.

It sounds like you've covered low airflow pretty well.
Unfortunately that leaves you low on a refrigerant charge.
You'll need to have the system checked for a leak and a recharge.

 

Thank you so much Pete,
I'll call a service technician to do the leak test and charge up the system.
Thanks again,
Frank

 

airflow, undercharged, or you may also have a liquid line restriction - capillary/orifice/txv, filter/drier, etc. so do not be surprised if that is mentioned.