Hi guys can anyone help I have a Daikin multi system 4mxs80e7v3b1 with 4 cassettes one of which is not heating and cooling most of the time. The other three heat and cool perfectly and sometimes the other unit works fine but seems to be only when the others are on aswell. I pretty sure it's not low on gas as the pressures seem there or there abouts. R410a. Changed the expansion valve head for one which works buy no success I ran out of time on site tho so was hoping someone could help for the next visit??
thanks

lee