Mitsubish 1500 fault

[Cmsaircon]

Hi guys .... We have re commissioned an existing mitsi r2 system , with 8 units on it , we had to move a few units and re cable it due to builders cutting several cables before we even got there .

Unfortunately we never witnessed the system running so we recovered all the refrigerant and did the works re pressured faced & re charged system the pipe worked we amended was same lengths as before so no re calculation gas charge was needed .... It's now complete but we have a problem when we run the system in heating , 1500 flashes up on all controllers !!! We don't seem to have this problem when we run the system in cooling . I'm aware gas over charge is 1 cause but we find this very hard to believe ... Unless it was overcharged to start with .

Any other ideas would be grateful cheers
Colin

[install monkey]

did all the units you moved get connected back to there correct remote controllers?, all indoors connected to correct ports? coil sensors faulty on indoor?? non condensibles

[Stephen72]

1500 - System overcharge. Abnormal low compressor superheat - discharge thermistor TH4

[marc5180]

1500 fault is activated when the outdoor unit registers less than 20'C discharge superheat for 15 mins or 10'C for 10 mins or more.

The best thing to do would be to connect gauges to the outdoor unit and measure the true discharge pressure then by using SW1 dip switch on the outdoor PCB compare with the discharge pressure that the PCB is seeing.
If the the PCB thinks the discharge pressure is different to the actual pressure on your gauges then replace 63hs pressure sensor.
Then measure the discharge pipe temp with your temperature meter and compare with the reading that the PCB is seeing again using SW1, this should be the same. If not replace the discharge sensor.
Or if possible swap with another unit just to prove that it isn't the main PCB that's at fault.

Or it could well be a locked open LEV on one of the indoors that is bypassing liquid directly into the suction line..... Something else to check.

[Cmsaircon]

Thanks for the replies , were back on site next week so will take a look at the points been made !!

Yeah all units have stayed on there ports , we have have altho changed all the controllers new par 30 !

Thanks