seized inv compressor

[flash]

HI Guys
I have a seized inverter compressor on a vrv I have to write a report for the client to try to explain why the comp is seized any idea's??

[Thermatech]

On some VRV / VRF systems you can get the total compressor run hours data from the outdoor unit circuit board.
If the compessor has done ,,, lets say 30,000 hrs you can diplomatically explain to the customer that the compressor has reached its life expectancy.
Most of this type of kit is designed to last for a target of 10 years running 5 or 6 days per week & 10 hrs per day. Total about 30,000 hrs.

If the customer had traditional chiller with semi hermetic compressor at what run hours would a complete compressor overhall be required ?

I have seen VRF systems still running on oridginal compressor & 50,000 hrs & that sort of longer life is usually due to good quality installation like dry nitrogen purge when brazing, good quality evacuation & good quality maintenance.

The weak point in a lot of these compressors is the shaft bearings. If the compressor is locked then pound to a penny the bearings have broken up.
The main cause of bearing failure is moisture in the system which makes copper coating of hot bearings & damage / failure.
The main cause of moisture in the system is poor evacuation at commissioning.

With VRV / VRF systems there are lots of system faults which can go undetected but will contribute to premature compressor failure.
If the system runs short of gas for 6 months between service visits the enduser may not notice but the compressor has been cooking at overheat conditions.
Reversing valve & check valve failures can also kill compressors.
Last year I did a site visit for a contractor who had replaced the compressor 3 times in 2 months. A check valve was allowing some hot gas to suction bypass which made the compressor overheat & failure in about 3 weeks. Customer was not happy & was only going to pay for the first compressor.

Some tips

1/ Look at the lable on the side of the compressor if its dicoloured then it has overheated.
2/ When you replace the compressor recover the full refrigerant charge to see if its lost refrigerant.
3/ Carry out an oil acid test to check for any acid. If acid is found in the compressor oil then then the most likely cause is moisture contamination.
Carry out system clean up procedure with compressor suction burn out filter drier.
4/ Mega test the comp windings to earth. If less than 1 mega ohm the inverter circuit may be damaged so you need to test run the inverter to make sure its ok. Otherwise after fitting the compressor you could then find that it still wont run bacause of damaged inverter & then have to tell the customer that he also need spend more money on inverter repair.
5/ When you get it running monitor the system performance very carefully to make sure no other fault in the system could be contributing to premature comp failure.
It only takes the LEV valve in one indoor unit to be locked shut. All other units will cool ok & reach set point. But the one unit with failed LEV valve constantly requests the outdoor unit to run. So the outdoor unit runs for periods of time when all the indoor units are actually not allowing any refrigerant flow so suction pressure goes very low & compressor starts to overheat.
In heating this unit with failed LEV valve fills up with condensed liquid thus effectively trapping a large volume of refrigerant & makes the rest of the system run SOG & compressor runs at overheat conditions.
So its important to make sure no other problems with system otherwise you will be back to another compressor failure & an upset customer.

[bobjob]

HI Guys
I have a seized inverter compressor on a vrv I have to write a report for the client to try to explain why the comp is seized any idea's??

Contact a compressor repair company like Preston Refrigeration telephone no 01675 470899
and tell them what you want.

They will strip down (cut open)the compressor and give you a report with photos if you wish on why they think the compressor failed.

They also have a lift and shift crew that will come and remove the compressor for you!

Regards Bob