Daikin my old friend

[ronaldo9]

Hi guys

I have the following

Indoor-------FDY P250B7V1
Outdoor ----RYP250B7W1

I'm wrecked and I can't remember if it wasn F1 or F2 that kept blowing , it's the one that feeds the safety devices and the indoor unit. Anyway it was popping fairly regularly when I got to site, I went through the usual, disconnected the indoor everything ok , long story short I had the unit running for 4 or 5 hours while I was doing other work, I had bypass the 2 fan thermal overloads, not best practice Sue me , I had disconnected the crankcase heater so i still had the two pressure switches and obviously the indoor connected. After running for the 5 hours I heared a loud bang, the fuse didn't just blow it blew completely out of the fuse holder and tripped the main 3 phase mcd, can anyone shed some light on what's going on here, the only thing i did notice was that the cable for the indoors was a 3 core flex at the outdoor and ended up being a shielded cable like .5 or something, maybe even less. This has been running like this for over 10 years , I didn't get much of a chance to check this out , just to say there are 3 other systems identical to this sharing the same remote, U5 faults all day when the fuse popped seemed to shut everything down any ideas ????!

[Brian_UK]

Check all the cable entries into any isolators, have the inner cable insulations been nicked when original wiring done?

Had it before on old systems, moisture starts shorting things out.

[padraic]

Previous faults I had with them units

faulty compressor contactor

faulty pressure switch

outdoor pc board blown due to fan overload linked out (pull out board look behind it) and the fan blades spinning freely. The way the wires are fed into motors its a pure trap for water (cut the ties and put a trap on wires)

a very rare one I had was indoor fan motor cable had come away and fan blade cut into it but you will have to remove blade and there's a bit of work to that

[CONROD]

Are you saying that the interconnecting cable indoor-outdoor is 3core flex one end & SY cable the other end? Sound s like you've a cable joint hidden somewhere. I had exactly the same fault recently on a 6 year old unit blowing the fuse that feeds the indoor unit intermittently. Eventually found a joint in the cable which passed underground as it entered the building it was typically wrapped in insulting tape and was damp, causing arcing between the cores - replaced the interconnecting cable completely no joints - problem resolved..