Toshiba Mar vrv blowing up compressors

[AlanP]

Whats going on with this unit? Direct on line compressor is blowing up contactor but variable speed part woks ok. New compressor only lasted 3 month before same fault recurred. Has anyone had this problem and a solution?

[Brian_UK]

Did you change the contactor when you changed the compressor ?

[The Viking]

Hard to say with just that info...

Assuming that you checked all terminals, wires and connections, as well as the voltage by the compressor (a royal pain on those machines) and that the inverted (part of the) compressor actually starts and runs.
Then you really need to get deeper in to it, preferable with Toshiba's ThermaTool (laptop).

We have replaced quite a few of these compressors but normally it's the inverter side that goes (as it runs the most I guess)

[paulwild]

hi, i have changed 2 comps (on differant systems) on this type of unit and its always been because of a fault with the inverter side of the comp , they are a real pig to change as well, but you are well advised to change the contacter as a matter of course as
with all comp changes may be worth checking the inverter board with a checker too

good luck

[TIGA]

Hi,please try and check on the type of contactor with its overload or the type of compressors u are replacing are not of good quality.

Wish u luck

[Andy]

Whats going on with this unit? Direct on line compressor is blowing up contactor but variable speed part woks ok. New compressor only lasted 3 month before same fault recurred. Has anyone had this problem and a solution?

Hi AlanP

I would be inclinded to check the size of the outdoor to the connected indoors, just a thought

Kind Regards Andy

[AlanP]

Thanks for the many replies. This unit seems to run ok with the D.O.L compressor disconnected as the windings are now down to earth. The customer has not noticed any deficiencies yet as the variable speed compressor bit still works OK. It runs 6 indoor units and is coping alright with heat demand, whether this will change I do not know!
It has had several new d.o.l contactors and eventually we put an oversize one in which eventally welded in like the rest. I wish I could replace the whole outdoor unit but Toshiba say it is obsolete and will only supply that stupid tin can with 2 compressors inside it. I wonder is it worth while repairing again?

[The Viking]

Alan,

As an engineer, I say rip it out and replace it with something modern.

Unfortunately so is it rare that the decision is left to us engineers.

You have to give the customer all the information, including the phase out of R22 and the fact that Tosh sees them as obsolete.
After that it's down to the customer to decide if they want to spend new money on old rope or not.

[chris96]

If the compressors using an oil equalisation line, check theres no damage or blockage and that the lines not bent or buckled, it may be the inverter is starting first and drawing the oil from the direct compressor thus getting starved of oil and seizing.

Just a thought.

Chris

[The Viking]

Chris,

Toshiba used a [sarcasms mode] fantastic/ingenious [/sarcasms mode] solution on these machines.

They put both compressors in the same shell, so no oil equalisation line there.

Not only does it makes the compressors expensive but it also transforms a simple compressor change in to something that requires lifting equipment.

The only good thing one can say about it, is that at least they learned from their mistakes, their new kit doesn't use these twinned compressors and looks really easy to work on. (time will no doubt tell)

[chris96]

Hi Viking,

I don't look after too many VRV's, the ones i do are modern Daikin or Mitsi's. It's a interesting concept tho

Do you have any pic's of these units?????

Chris.

[The Viking]

Unfortunately only external ones, go to my website and look for the work related photos.

[OzKin]

Ive changed about 7 of these bugggers, and they are a royal PITA.

Your saying windings down to earth, with the Tosh laptop, you can tell the D.O.L discharge temp, might give some correlation to the D.O.L overheat, and widing burnout.

This is the R407 OR R22?

edit, what amps was it pulling from the contactor? iirc, the newer Contactors have a bigger O.L rating.

ta

[Si@airconworld]

I have had pressure problems with these systems and 2 engineers went before I, if that doesn't sound too arrogant, figured out.

It turned out that the installers had put one of the evaporators in the server room. This meant that when everyone went home the lumping massive condenser was just serving the one tiny evaporator all night.

This caused it to trip out most nights, why doesn't the INV backdown to compensate... somebody else might have the answer but I couldn't tell you. Anyway the point is that the client had figured out that all he had to do was reset it in the morning and it would work all day - but that meant all night long the pressures on the compressor were emense and short cycling was occuring unchecked.

Just a thought...

[Chunk]

HI. i`ve had the same problem as above.the outdoor unit was wired into the essential services of the building and when staff went home at night all a/c was off but outdoor unit still ran thus burning out comp and/or contactor.