It keeps going on, off, on ,off, on then stays off. I was told the coils need to be cleaned. How do you clean them? It's a Rheem and about 3 years old. I have a lot of iron in my water and had to replace the pump on my well a few months ago. Rheem says the coils needs to be cleaned, it's not getting enough air. How do I do that? Also,I bought mine in Oct 08 and have have replaced the circiut broad,the memory chip and reprogrammed it .