$900 is way too high, $400 is what a new A/C Servo should go for. I learned a trick that made mine work better, I would problems with it being too hot, or too cold or it would just stop working when I was on a long trip. Try setting the temp to 65 and have it on high, do this for maybe 5 minutes, then put it on defrost for 5 minutes. Switch back to high for another 5 minutes, and just keep switching back and forth for a while. This sometimes will help make them work better.