MHI problem

[markh85]

I have a e48 fault on this spilt system previous engineers have changed the outdoor fan motor and the PCB but unable to get the unit running anyone else had a similar problem??

[croc1774]

Model number would be helpful but sounds like a transformer problem from AC-DC.
Regards

[markh85]

Sorry not at the unit it's a new 410a unit was installed about 2 years ago twin fan condensor and a ducted indoor unit I think it's a FDCN804?

[Andy AC]

Have you had power on to the condenser for a few hours? If you have just turned up to site and just switched it on, it won't go until the crankcase heater has warmed up and been on a while. This is a real pain in the ass on MHI units, especially with the current low ambient temps. You do your job safely and turn machine off before any work on it, change a motor, clean coil etc. switch it back on ten minutes or so later, and then you have to wait forever for it to regain its temp.:(
On the main board there is a 2amp fuse for the fan motor, it is soldered on to the pcb. As you said it was a twin fan, it may have two fuses. You might have been unlucky and lost the other fan motor. MHI do a fuse repair kit which clipped on to the damaged/blown fuse - much cheaper than a new board.

Andy

[Greengrocer]

Had exacly the same problem a few years ago on a single fan MHI outdoor (10kW FDC R410a model). The soldered fan fuse on the board blew because the fan motor bearings were coroded causing the motor to overload - on a then new unit. If this is the problem you need a new fan motor and a piggy back replacement fuse. To check the fan motor remove the fan blade and try rotating the motor shaft by hand . If it's stiff then the bearings are seizing up.
What idiot designs a PCB with a fuse that's soldered in place & can't be replaced! We went through two PCB's before we got wise.