I have a 2003 National Islander with two Duo Therm heat pumps and have not been happy with the performance of the units. I contacted Holland Motorhomes in San Diego about service on the units and the service writer told me that if the units are low on refrigerant, the units cannot be recharged and will have to be replaced. Not beleiving that Dometic would put out a product that could not be re-charged, I emailed Dometic with that question. Dometic customer service got back to me and without giving any reasns, said they do not recommend re-charging their units and suggested where to buy new units. This sounds like a crock to me! We are able to re-charge the A?C units in our homes and our cars but, can't in our motorhomes? Has anyone had the experience on servicing the Duo Therm heat pumps in their coaches?