I've been having heat pump problems and have had professionals visit twice already. The first time, he said the defrost sensor fell off and he put it back on. The problem continued, so the second time, he replaced the defrost sensor. Now, the outside unit is not completely freezing over the way it was before, but it does still have a little frost on it. I turn the heat down every morning to about 64 degrees. When I get home, I turn it back up to about 69 degrees. Yesterday, it took one hour and 25 minutes for the house to reach 69 degrees. I'm scared there's still a problem! The temperature is only in the 40s/30s. Is this normal? Once it reaches 69 degrees, it usually comes on for about 27 minutes and goes off for about 8 minutes. Is that a normal cycle for moderate weather in southern Virginia or should I call another professional?

 

Sounds as though you have a freon problem. But with the weather problems you've been having the unit may be running the best it can. High moisture content in the air can cause excessive condenser frosting.

 

This is the primary frost temperature to appear. That 30-40 degree area is when you will see the most frost in most cases. Are you seeing three belts of frost , top, bottom and middle? OR are you seeing it only on the bottom....if its only on the bottom it MAY be low on refrigerant. With a package unit you can put in a weighed charge...but with a split system you can guestimate at best using charts but manufacturers reccomend charging in the cooling mode and unless the outdoor temps are above 70F it's pointless. I would reccomend you have the gas recovered in a clean cylinder with a deep vacuum and the recovered gas weighed and compare to the stock charge(usually good for a 15' line set, then calculate the volume required in excess of 15' to fill the lines and add that to the required amount, . Have him replace the dryer and pull a deep vacuum for at least 1 hour. Then recharge the unit...This will ensure you have a proper charge and get a new dryer in place to protect the compressor. Have him install a Sporlan Bi-flow HH (activated charcoal filter) in the liquid line. If there is any acidity in the system or waxes, this filter will clean it up, it's a little more money but well worth the cost. Keep in mind when you hit about 27F your strip heat will start to kick in to try warm the place. Feel the fat insulated pipe in the house by the air handler, It should be hot after 7 or 8 minutes of run time. If not she's most likely low on gas...also check the condition of the 1/2" (not 3/8") armaflex outside, is it above ground and in good condition, it may be loosing its heat to the outside BEFORE it comes in!