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garyjh24
17-04-2008, 08:07 PM
Hello everybody,

Please could you help??
Just taken over the contract on a new site, the site has a Mitsubishi City Multi PUY-P250YMF-B, R407C. The unit is showing 4210 error,breaking of over current.Having spoken to the customer, the history of the unit is....
Compressor failed approx a year ago, appeared to be electrical fault. Fault code 4210. New compressor fitted.
PH test reveals no acid problem.
9 mnths later (approx) compressor appears to fail again. Fault code is 4210.New compressor fitted, this time in-line cleaners fitted.1 month later, same code - 4210. Compressor appears to be OK via on-site tests.
Complete electronics sent to (old contractors) for analysis.
They say that there is nothing wrong with it.
(old contractors) are now suggesting that they come in for a diagnostic visit.
I visited site on tuesday and found customer has switched unit off at isolater. I have'nt run the unit yet as i want to energise the crank case heater for 24hrs. I have checked all the electrical conections, found lots of lose screws on the transistor modules, tightened. I've re tightened all connections elsewhere.Checked the main distribution board supply and cable to the unit, all ok (only noticable thing is voltage is 419v between blue and yellow, but when red and blue/yellow checked only 413 volts).Only other thing is due to the unit cooling a comms room, and is required to run all year round a head pressure control has been fitted ( danfoss HP switch connected to contactor with c/u fan attatched, cuts in at 300psi, out at 250psi) I am informed that this was fitted by a Mitsubishi engineer.
I'm returning back to site once the crank case heater has done its job, i'm going to test the inverter, check the refrig pressures and fan etc. The customer has said that this 4210 code only appears every now and then. Would any of you have any other recommendation or help with this matter??

The Viking
17-04-2008, 09:49 PM
Hmm,
What happens with the separate FSC when the unit goes in to "mainly heat" mode?

Running comms rooms from VRV/VRFs are always dodgy...
Even with a separate FSC, the outdoor unit and the condensor will be over sized with a lot of refrigerant building up in there.
The VRF system would try and compensate for low suction pressures by injecting hot gas to the suction.
Any other pre alarms in the fault code memory?

I'm just guessing, hopefully Thermatech will be around shortly.

Before you start the unit up, disconnect the compressor and do a dry run of the inverter, checking it's output.

And get a laptop [M-tool] on the system to fully check it out.

good luck.

SUBCONTRACTOR
17-04-2008, 10:00 PM
Hello everybody,

Please could you help??
Just taken over the contract on a new site, the site has a Mitsubishi City Multi PUY-P250YMF-B, R407C. The unit is showing 4210 error,breaking of over current.Having spoken to the customer, the history of the unit is....
Compressor failed approx a year ago, appeared to be electrical fault. Fault code 4210. New compressor fitted.
PH test reveals no acid problem.
9 mnths later (approx) compressor appears to fail again. Fault code is 4210.New compressor fitted, this time in-line cleaners fitted.1 month later, same code - 4210. Compressor appears to be OK via on-site tests.
Complete electronics sent to (old contractors) for analysis.
They say that there is nothing wrong with it.
(old contractors) are now suggesting that they come in for a diagnostic visit.
I visited site on tuesday and found customer has switched unit off at isolater. I have'nt run the unit yet as i want to energise the crank case heater for 24hrs. I have checked all the electrical conections, found lots of lose screws on the transistor modules, tightened. I've re tightened all connections elsewhere.Checked the main distribution board supply and cable to the unit, all ok (only noticable thing is voltage is 419v between blue and yellow, but when red and blue/yellow checked only 413 volts).Only other thing is due to the unit cooling a comms room, and is required to run all year round a head pressure control has been fitted ( danfoss HP switch connected to contactor with c/u fan attatched, cuts in at 300psi, out at 250psi) I am informed that this was fitted by a Mitsubishi engineer.
I'm returning back to site once the crank case heater has done its job, i'm going to test the inverter, check the refrig pressures and fan etc. The customer has said that this 4210 code only appears every now and then. Would any of you have any other recommendation or help with this matter??


4210 is overcurrent break.Obviously you have to check the units output with disconnected compressor. And as Viking said if you mange to get hold of Mtool this is gonna save you lots of time.;)

garyjh24
17-04-2008, 10:20 PM
the only other fault codes (on a centralised controler) for this system is 6607. The fault codes history goes all the way back to 1st sept 07. the only codes for this system are 4210 and 6607. there is no pattern with these codes among the time frame, the 6607 could be where the customer has been turning the unit off to try and reset it??

The Viking quote " what happens with the FSC when the unit goes into mainly heat mode?" The unit is a cooling only model, or do you mean something else??

Thanks for your help guys

Thermatech
18-04-2008, 01:09 AM
To be fair you have looked at relavent suff.
4210 can be due to poor power.
Inverters need well balanced power supply so loose power terminal screws can often result in £££ of damage.
Make sure fire alarm or generator test does not cut power to outdoor unit suddenly.

1/ But if the power supply looks a bit un ballanced what about other times of the day. Is the power supply getting a surge when other stuff in the building switches on/off.
Make absolutely sure the Neutral is good with no measured voltage earth to Neutral because any poor neutral terninal in power supply can kill comp / inverter.

2/ Suggest do your own oil acid test if you can get an oil sample. Dont trust what other tell you.
Acid contamination will kill motor windings.

3/ Make sure the compressor windings with Mega = less than 1 meg ohm before start up.

4/ The system is perhaps 1999 vintage. The Lev valves have been ramping open / shut 24/7 for all that time.
Monitor operation of LEV valves at outdoor unit & also indoor units for correct operation because locked open or shut LEV valve could be contributing to premature compressor failure.
The outdoor unit will have an oil return LEV valve & if that is locked shut poor oil return will kill comp bearings. Also subcooler LEV & if thats locked wide open then lots of liquid gets dumped back in the accumulator.

5/ This systems were never designed for low ambient cooling with less than 15 deg C wet bulb indoor on coil.
The outdoor units low ambient control was unable to cope & units needed HP override low ambient control to prevent over condensing.
When adjusting the HP control you need to look at the indoor coil temperature of TH2. If the temp at TH2 falls below 1 deg C then the unit stops cooling for a few mins on coil frost prevention mode.
The discharge pressure at the outdoor unit needs to be adjusted so that the indoor coil temp stays just above the 1 deg C to ensure the indoor unit continually cools & does not keep entering stopping on coil frost prevention.
This usually means pushing the discharge pressure quite a bit higher then you would normally but it drags the evaporating pressure / temp higher & when that gets high enough then its will stop the coil frost prevention problem.
If the outdoor unit is below the indoor units then you will really need to push the limits & this will impact on compressor life.

6/ The hated 407c. has the system been toped up a number of times to keep it going ? Is the refrigerant composition correct.
YMF-B models started with R22 & only very breifly supplied with R407c before upgraded to YMF-C model.
The YMF-B units did not have the all important refrigerant composition sensing circuit which was later used on the YMF-C models.
This prevented fractionization problems.
If the unit runs for long periods of time at very slow compressor speed or constantly stop / start then all the low pressure 134a gets trapped in the accumulator & the compressor just pumps high pressure R32 & R125 arround the system. This results in excessive high pressure & over amps.

Because the system was mis applied & will have been operating well outside its design operating limits for so many years its not going to be easy to make it work with good reliability.

Sorry for ramble.Best of luck & let us know how you get on.

garyjh24
21-04-2008, 09:11 PM
Thanks for all your help guys.

Well i returned to site, performed an insulation test on the compressor, all OK, checked the inverter (removed the condenser fan from the add on head pressure control and re wired to normal connection) all three phases the same.

Double checked all the neutrals, all ok.

Run the unit, found the connections on the compressor pulling amps as follows, connection U 27amps, connection V 13amps and connection W 13amps. Compressor sticking? After 5/10 seconds unit shut down and produced 5301 fault.

Double checked all above again then tried unit again. Once again units amps a little high on connection U, but quickly begin to drop until all three connections pulling 13amps. Unit running.

Checked refrigerant pressures, suction very low at 20PSI, discharge at 180PSI (head pressure controller still removed, ambient temp 12 degrees C)

Checked pressures at burn out driers, no blockages.

Have recommended that refrigerant is reclaimed and weighed, oil test performed, burn out driers replaced and unit commisioned. With correct charge in system i can then check all the LEV in indoor and outdoor unit.

If you guys think theres something i've missed, your suggestionswould be appreciated.

Thanks again everybody.

nike123
21-04-2008, 09:30 PM
Run the unit, found the connections on the compressor pulling amps as follows, connection U 27amps, connection V 13amps and connection W 13amps. Compressor sticking? After 5/10 seconds unit shut down and produced 5301 fault.



Imbalance in current tell us that something is wrong. Could be inverter circuit. You should try to make test with direct connection to 3 phase line voltage if it is AC inverter and (after prolonged standstill period) try to start compressor and measure current imbalance.
If compressor is mechanically damaged, current would be higher but balanced. If windings are damaged imbalance would be all the time.

Thermatech
21-04-2008, 11:31 PM
The 5301 fault relates to the inverter board & the d/c circuit current detector.Thats not at the supply to the compressor but between the rectifier ( diode stack) & the TRM units.
It will trip at less than 10amps or more than 20 amps at start up.
For instance if you try to run with the compressor disconnected you will get this fault.
To test for correct operation of the inverter you need to set a dip on the inverter board to disregard under current. Disconnect power leads to comp & make safe. Then run system. Measure earth to each phase or N to each phase. Each phase should have the same voltage reading. It does not matter to much exactly what the voltage reading is just that all 3 are ballanced. The voltage reading will depend on the specification of your meter. Some engineers also like to measure between each phase & again it should be ballanced.
This is the acid test for the inverter operation. If you have ballanced supply from the inverter with nothing connected then 99% sure its ok.
I like to connect a small 3ph fractional hp motor instead of the comp but this is only for the visual effect of seeing the shaft rotate & speed up.
Next do the same again with compressor connected.
Make sure to reset the dip on the inverter board. ( I often forget )
If you have any other units the same model on site you could swap the current sensor to see if that resolves the problem.
Or you could swap out the complete inverter pack & see if the problem goes with the inverter pack or stays with the unit. Its not such a big job but can help to identify intermittent faults.
The 27 amps on one phase at the compressor is not excessive. At 40 amps I would suspect the comp.
The difference between 27 amps on one phase & 13 amps on the others makes this further investigation of the inverter needed to be sure which is the problem , inverter pack or compressor.

You now see why the additional HP control is needed with such low discharge pressure the suction pressure is also much too low at about minus 15 deg C. The indoor units will be stopping every few mins on coil frost prevention & the outdoor unit will be stop/start with lost cooling performance at indoor units while recovering from coil frost.
To get better performance the temperature at the indoor coil needs to be above +1 deg C to avoid CFP.
Then the indoor units runs untill room temperature satisfied.
300 psi / 20 bar is ok for the discharge pressure, that about what the unit would normally run at on a 30 deg C ambient day. But 180 psi / 12 bar is much too low badly overcondensing.
I know its a pain in the neck having to keep going back. If its any consolation I had to do quite a few of these before I gained confidence in doing inverter diagnostics but that was over 10 years ago.

lonemascot
14-05-2008, 07:03 PM
haven't read the posts but i had a 4210 fault after changing the compressor, inverter board and main board. Turns out the transistor modules behind the main board had exploded. Possibly due to the compressor going or may have been the cause because of a lack of heat dissipation. who knows.

kooltech do a full diagnostic on the inverter pack and replace only the faulty parts.

ozairman
15-05-2008, 11:49 AM
I like to connect a small 3ph fractional hp motor instead of the comp but this is only for the visual effect of seeing the shaft rotate & speed up.

The 27 amps on one phase at the compressor is not excessive. At 40 amps I would suspect the comp.
The difference between 27 amps on one phase & 13 amps on the others makes this further investigation of the inverter needed to be sure which is the problem , inverter pack or compressor.

Hi Thermatech how big is the three phase motor that are you using? and how long will it run for does the compressor rotor detection circuitry trip out if you connect a conventional motor?

Also every time I see imbalance of phase amps like above on SCI scrolls it has been a compressor that is siezed mechanically (mainly on Siam Compressor Ind ANB series which is Mitsi Elect design built in Thailand affiliate factory)

Thermatech
15-05-2008, 11:02 PM
ozairman

I just use a 1/3 hp fractional motor.
Its just reasuring to see the shaft slowly turn & then ramp up on startup.
You dont need it if you do the voltage measurments or use an inverter checker instrument.

The later 407c & 410a City Multi units will stop on low amps fault so you have to change a dip on the inverter board to disregard low amps.
On the older R22 units there is no low amps fault.

Williamt
26-10-2009, 10:59 PM
Would anyone be kind enough to attach a copy of the Mitsubishi City Multi Erro code book
Regards

spikey007
20-11-2009, 09:34 AM
e-mail me for error code list: technical@msaircon.com