I recently bought a house with a 2004 goodman heat pump. During a recent cold spell I learned the referidgerant ran out so I had it filled. Within 24 hours the system was blowing cold air. Another repair guy came out and told me the valve inside the heat pump was broken and could not be replaced so he could set me up with a system for $8000. Can this valve be relaced? Or am I screwed up in thinking anything can be fixed?