Daikin Cassette Fault

[symon22]

first of all good evening,
i have been asked today to have a look at a daikin cassette in a pub that has a fault.
i have'nt had much to do with these units so please bear with me.
first fault is communication code u4 from what i can read into the wiring diagram i think this would be wire 3 to the outdoor unit.
the internal p/c board had a burn mark on one of the tracks and no flashing led. the board was replaced and now blinks green as it should do as i read it.
the evap fan did not operate so i checked the feed through the fan capacitor and it had power through it no probs.
so i removed the motor and tried it on the other parrallel evap ,it worked fine.
so the questions are,if you could be so kind, are

any further ideas on the u4 code and what button sequence do you use to clear/reset the daikin hard wired controller

and would any of you guys have any further ideas as to what might be preventing the fan motor operation.

not being to familiar with daikin product, i've probably shot straight in deep and gone straight past the obvious answer.

thanks guys.

[stuartwking]

Hi symon22 and welcome.
Some more details would help. Is it a split or a vrv?, You no that U4 code is loss of comms between indoor and out door,.
Im guessing its a split system?
Whats the model numbers?.
If it was a outdoor board that was the fault and it was replaced, switching off and on the outdoor would clear the fault. Maybe worth while checking outdoor transformer and see what voltage you have down your comms wire to the indoor.
I would sort out your comms fault first then try looking at the indoor fan motor.

[symon22]

thanks stuart,
its a split , one outdoor feeding two indoor cassettes. cassette number is FHYCP125B7U1 R407 2004 model.

can i ask what sort of voltage output you would be looking coming from the outdoor t/former.
shall also check if there is an isolator next to the indoor unit breaking the number 3 coms wire as i've heard this can cause the fault u4 as well. .
thanks for you help..

sometimes i think to myself why they try to make cold air complicated...

[Major Phucup]

to clear fault code from controler while code is displayed press and hold on/off to code disappears

[frank]

to clear fault code from controler while code is displayed press and hold on/off to code disappears

This is only true when the fault has been fixed and the red indicator light is no longer flashing.

If the fault code remains and the red led blinks then the fault is still present.

It is sometimes the practice to wire the comms wire (number 3 on a FHYCP125) through the high limit in the condensate pump. Check for continuity on the number 3 wire, or alternatively, install a new temporary wire between indoor outdoor units to see if this clears the fault.

[marc5180]

thanks stuart,
its a split , one outdoor feeding two indoor cassettes.

don't mean to be facetious but it's a twin.