Another U4 Daikin VRV III problem

[sunilc]

I have a new Daikin VRV III with about 15 indoor units. Have had u4 issues show up 3 times. First time just reset everything and it worked for a month. Next time they suggested replacing all the control wiring at the indoor units which they supposedly did. It happened again so they replaced the pcb on the outdoor unit.

It has not happened yet but today one of the indoor units had a flashing red light which one time before was a precursor to the whole system going on a u4 - after a few days I found all the units flashing red lights and the noticed the u4 code on the master.

Today I switched the flashing unit off and on and it seems to be fine but based on my previous experience something is going to go wrong in a few days I am sure.

Has anyone else experienced this and have a solution? I am just the user so will want to feed any ideas to the technicians who I have already made aware of this latest issue.

Thanks.

[Krondor]

From my previous experience, if the control wiring has been already checked (and tightened at the indoor unit terminals) i woiuld suggest to check the power supply wiring at the indoor units terminals. What may happen is, that if the Power Supply wires have a "loose connection" at one of the terminals it may cause the indoor to "drop" out of the system. When outdoor can't "read" this indoor, it shows "U4" on the whole system.

Then, if the U4 doesn't dissappear by itself you may need to reset it by shutting the power off and returning it back.

[brunstar]

it does sound like there is either a loose connection on the F1 and F2 control wiring, high resistance on the F1 and F2 cable from pulling them in or as the previous post says. Loose 230volt feed to a unit.