vrv 3 f3 fault code? need help

[raz10]

hey guys i recently went to look at a vrv 3 system, an error code came up which was f3 high temperature discharge probe, i down powered the unit and re powered, the fault stil occured. i checked each probe on all 6 compressors and could find no sign of burnt probe, i also did a system run on test mode to see if there was a refrigeration leak, no loss of refrigerant found? what else could this be? all help will be much appreciated.

[Brian_UK]

And what is temperature of the compressor discharges ?

[raz10]

i could only test one compressor as the condensing units went in to defrost mode, discharge was 104 degrees and the suction was 2 below zero? any ideas?

[Brian_UK]

Fault finding from basic Daikin

[raz10]

thanks for that much appreciated, i mean i have checked most of these already its just a really strange fault :s

[brunstar]

is it a new installation?

[raz10]

it was installed 2 years ago

[Brian_UK]

Maybe a sensor going wobbly when it heats up?

[troymedhurst]

just and idea, Had F3 before when one of the fans was working intermittently,but the other fan was stopping it going out on hp and the discharge temp was going too high causing f3 replaced dodgy fan motor and no more faults.
good luck

[Mentallist]

F3 error is generated when the temperature of the compressors reaches either 125 degrees 3 times within 30 mins or 135 degrees is reached. The system attempts to lower the overheat of compressors by using the sub-cooling circuit as liquid injection, and/or in the case of the inverter compressor - Reducing the frequency when 115 degrees is reached and the sub - cooler is unable to reduce the temperature (This is called drooping or stepping down control and can be viewed on the service checker when the control is active).

If the standard compressors are over heating, these cannot (for obvious reasons) be stepped down in speed, in this instance, they are turned off for 10 minute periods by the software. If the system will not operate or reset, and F3 is constantly shown, resistance measurement of the senor should be taken and also the temperature of the pipe, compare the results to the table in the service manual to check the sensor is reading correctly. If you are unable to judge which sensor for which compressor is causing the issue, try using monitor mode binery 14, the led sequence will tell you (if you follow the correct method) which sensor/compressor is generating the fault. Best of luck