I have been working on a Rhud Rheem 2.5 ton heat pump for the past two weeks. It has had multiple problems; replaced the reversing valve, accumulator, and filter dryer. I thought that I had the problem fixed. I put a good charge on the system and it seemed to be running well. I got a call that the unit was not blowing warm air (the ambient temp was 33 degrees). I check the outside unit and found the accumulator and compressor suction line are iced up. I am not to sure what to check next. Possibly the defrost timer? if anyone has had trouble like this and knows what the problem might be please let me know.