The residents of our housing complex have 12 Fujitsu Mini Split Ductless Heat Pumps(ASU9RMLQ) that were installed about five years ago. About 25% of the units are non-functioning and a few of the units have run for less than a few hours in that time(some not at all) mostly because of problems that have been associated with the units. Most of the residents are seniors and several are wanting to sell their unit and would like to have the heat pumps functioning for that purpose. We intend on trying to engage a HVAC technician to assist us and to work with us on an ongoing basis but would greatly appreciate some expert advice before we proceed.
There are a variety of problems associated with these Fujitsu units but the one problem that is common to all the unit is that they were installed with a 1/2 inch suction line rather than a 3/8 inch line as specified by the manufacturer. We attempted on a number of occasions to get some advice from Fujitsu but about all they said was that the warranties on our units are void because of the 1/2 inch line and that we should talk to the installer about it and would not recommend another HVAC technician in our area who would be qualified to work on Fujitsu units. The installer has quit the business. We have had four different HVAC technicians on site at various times and have received conflicting advice with respect to the suction lines. Two have said that the 1/2 inch lines have to be replaced with 3/8 lines at a cost of thousands of dollars per unit and involving significant damage to the walls of about 1/2 the units at least. Other two HVAC technicians said that although the 3/8 inch line would have been preferable the 1/2 line is still acceptable given that the coolant is in a gaseous state in that line. When the compressors are operating the pressures within both lines are well within the parameters specified by the manufacturer and the temperature difference between the in flowing and out flowing air in the wall units where the heat pumps do actually work is about 20F. We realize that operating the units with the 1/2 inch line could affect the life of the units but it is a very temperate coastal climate here and the pumps would only be used for a few weeks in summer and a few hours on the occasional day in winter.
The decision to install Fujitsu Heat Pumps in our complex has turned out to be most regrettable. Now that we have them, however, we would like to make the best of a bad situation. We would be most appreciative for any advice that may be provided to assist us in putting this problem with the line sets in some sort of perspective.