I have a 4 year old American Standard heat pump. It has leaked freeon and has been running on empty for probably over a month. We have a separate system in the other part of the house that has been trying to make up for the heat loss. The impaired system has been blowing cold air. I have had several technicians check on it. One found a leak in he line in the outside unit. He thinks he repaired it but believes now that the expansion valve is bad. Other techs who have looked at the system think there may be more leaks and say that the compressor has been comprised by running so long without freeon. There is not a shutoff on this unit when there is not freeon. The system runs until it is in danger of overheating and then shuts down the compressor. The cold air still blows.
Question is if I change out the expansion valve is that still going to leave me vulnerable because the system ran so long without freeon. One tech said that the outside unit and the inside unit need to be replaced along with all of the freeon lines because it has all been comprised by the contaminated oil. The unit is under warranty for parts but no one seems to think that American Standard will give me a new unit. Please help.

Replace whole thing

I would try american standard. Your unit is under warranty but the conditions of its operation could be of a concern.

And beware of the people that put it in the first time,, any equipment is only as good as the installer,, high dollar equipment isn`t worth much if the installer does shoddy work