Daikin VRV 3 pipe changing mode

[multisync]

Multi,
It sounds like you’ve had one of those days
At least you didn’t need to dig your way through the snow to get up the street on the way home

U4 errors can be real pain on older installs, especially when it’s an intermittent fault.

You will probably be aware of the most common reasons for a U4;

• Mains power off at indoor/bs/outdoor
• Loose live or neutral connection
• Mains power has been switched off/on but system fails when reinitializing (turn power off/on again and hold down reset button for 10sec)
• Bad connection on F1F2 comms lines
• Mice or rats chewing into comms cables!
• If it’s a KJ outdoor unit the small green interface pcb that f1f2 cable connects to has been known to cause probs.
• Faulty indoor/bs/outdoor main PCB (never had this with intermittent U4 error)
• K series units can be very slow to recognize a U4 error and
• U4 errors will auto reset when comms are reestablished

Let me know how it all works out

Took me 1 1/2 hrs to go 3 miles this afternoon.

We've had rats chew the comms cable in a hotel once and a few of the others here and there. This is a strange one and we can only hope that it holds till Christmas.

The install is only just (and I mean 3 weeks just) 3 years old. It's sad they are failing like this. I won't tell you what the UK facilities Director thinks of Daikin after this and an even worse site up north somewhere....


Just to cheer you back up I am mid swap on a Tosh SHRM: 3 condensers multiplexed and so far in 2 years 3 compressors failed out of 6 !