Mitsubishi PUHZ-HW140VHA UF Error

[khorgan]

http://youtu.be/wUFrYuswhcEHello All,
I'm new to this forum so apologies if I'm in the wrong forum.

I have a Mitsubishi Ecodan 14kw Air-Water Unit showing up a UF Error (which is an overcurrent error caused by a Compressor or Compressor Power Supply).

My first step was to check the Voltages coming from the three Powerboard lines to the Compressor and they are OK (Reading a steady 180Vac).

I then did a resistance test across all the Compressor Terminal (U-V-W) and each are reading 0.3Ohms (Which suggests no Opens or Abnormalities in the Compressor Windings).

My issue is the on startup the compressor starts 'clicking' and then UF error occurs. I'm not sure if the compressor is at fault or if something else could be causing this. This is a link to a video in which the clicking can be heard ( http://youtu.be/wUFrYuswhcE ) .

Any help is very much appreciated.

[install monkey]

Compressor overcurrent interruption
(When compressor locked)
Abnormal if overcurrent of DC bus or
compressor is detected within 30 seconds
after compressor starts operating.
1 Decrease of power supply voltage
2 Looseness, disconnection or
converse of compressor wiring
connection
3 Defective compressor
4 Defective outdoor power board
5 Decreased water flow
6 Clogged filter of water pipe
7 Clogged plate heat exchanger
8 Locked water pump
9 Malfunction of water pump
1 Check facility of power supply.
2 Correct the wiring (U•V•W phase) to
compressor.
Refer to 8-6 (Outdoor power circuit board).
3 Check compressor. Refer to 8-4.
4 Replace outdoor power circuit board.
5~9 Check water circuit and repair the defect.

[install monkey]

check ur e mail

[khorgan]

Thanks for the info. Service manual was a great help.

I checked the water flow. No problems.
I check the refridgerant flow path and the 4-way valve and coil. No problems.
I checked all the electrical stuff (fuses, relays, thermistors etc....)

Leaves me with one conclusion, the DC Scroll compressor is gone. The clicking coming from it must be from the scrolls banging together. Electrically the connections on it are Ok, but mechanically it's busted.

It's probably the most expensive part of the whole unit. Yikes.....

[install monkey]

warranty???

Thanks for the info. Service manual was a great help.

I checked the water flow. No problems.
I check the refridgerant flow path and the 4-way valve and coil. No problems.
I checked all the electrical stuff (fuses, relays, thermistors etc....)

Leaves me with one conclusion, the DC Scroll compressor is gone. The clicking coming from it must be from the scrolls banging together. Electrically the connections on it are Ok, but mechanically it's busted.

It's probably the most expensive part of the whole unit. Yikes.....

[RusBuka]

If the compressor jammed, it is unambiguous not a guarantee case.
You saw it, look color of oil and its quantity.

[install monkey]

http://domesticheating.mitsubishielectric.co.uk/information/faqs/maintenance
3 yr warranty

[khorgan]

Yes the compressor was at fault on the unit.

Thanks to Mitsubishi for recognising the problem and replacing the entire heating unit rather than replacing the compressor alone. Apparently this type of failure is incredibly rare and as the unit was only two years old, there may have been an inherent problem from the start.

The new heating system is the upgraded model PUHZ-hw140vha2-bs.

I'm a very happy man again and glad I don't have to switch to oil!!

[Tayters]

Bit late now but glad you got it sorted. The 180V you measured going to the compressor, was that to earth or between phases?

Should be measued by disconnecting the compressor, get system to run compressor, measure voltage between phases and see if they read the same peak voltage. AC splits normally go to around 120V AC but this could change depending on inverter and test meter.

When system is on idle you can get a voltage to earth but between phases 0V AC

[install monkey]

andy mitsi compressors ,inverter driven when it trys to start has 180v accross comp terminals ( and to earth or neutral- simulates 3 phase output) check out ur guide to testing inverters! :o


Bit late now but glad you got it sorted. The 180V you measured going to the compressor, was that to earth or between phases?

Should be measued by disconnecting the compressor, get system to run compressor, measure voltage between phases and see if they read the same peak voltage. AC splits normally go to around 120V AC but this could change depending on inverter and test meter.

When system is on idle you can get a voltage to earth but between phases 0V AC

[Tayters]

Ah, the Inverter testing guide - a work of art but still waiting for my nomination in the Man Booker Awards.

[install monkey]

http://www.refrigeration-engineer.com/forums/attachment.php?attachmentid=9653&d=1351104140