Compressor seized up on me

[properdouble]

Hi Guys
Me again with wierd problem. Turned up to a call out freezer not running effieciently got to test condensing unit as was showing temp at start of deefrost -18. However after flicking on and off real temp was -12. Started checking condensing unit noticed bottom of condenser cool as well as drier. Carried out pump down test condensing unit was looking fairly new as well as evap. It was pumping down to 0 psi and stood there wasnt pullong vacuum. I recovered all 404a , carried out hp test, changed drier evacuated below 1 torr and charged to full site glass. I charged less than recovered by about 500g. Whilst testing i noticed half evaporator frozen and half not. Anyhow i tought i do one more pump down test before leaving site so i fully forward sit reciever rota lock and was waiting while it pull down to 0 psi and all of sudden sparks came out of box on the compressor where all 3 phazes are coming. I reset braker turned it on and same thing happend. I have never seen something like this. It was copeland compressor scrool i think. I quoted compressor and new TEV. Will go soon to change it just wonder what could cause compressor to pop out and was it the problem in the first place. I am going grey and i was scared that they will blamee for causing fault but likely they where fine with it.
Many Thanks hopefully i will learn something again from those who have more expierience.

[Brian_UK]

If you saw sparks coming out of it why on earth did you try and restart it without checking the electrics?

[monkey spanners]

Not all scrolls will pump into a vacuum, though i doubt your testing caused the failure.
Would be more likely due to the problem that is causing only half the evaporator to frost over. Could be tev, but could also be a problem with the distributor.

[FreezerGeezer]

Are any scrolls ok to pump into a vacuum? I've always been told never to do it to a Copeland / Danfoss / Trane & just assumed that holds true for any scroll.
Besides, as there's no valves I wouldn't have thought it'd be capable of pulling much, if any vacuum?

[properdouble]

Hi
going to change it on Tuesday i will change TEV too in regards to checking electrics i did and they looking like new no burnmarks on the compressor terminals whatsoever only black powderish residue around that circural cap where 3 terminals for all phases are sticking out on compressor very weird i hope new compressor will run. Any tips what else to check during replacement? By the way dose it matter where all phases are conected on the compressor? I will check contactor to ensure i got all phases before starting new comp but loosing one of them wouldnt cause sparks comp jut woudnt run is in it?
many thanks.

[FreezerGeezer]

Don't forget to wet rag the TEV.
Megger the compressor before you install it.
Pull a good vacuum. Triple vac. is best.
When you checked the electrics, did you just look at them or did you actually test them? What were the readings?
Is there now a refrigerant leak at the terminal block? If the 'black dust' wasn't there before the arc, then something's got damaged. Arcing is usually caused by loose connections. Be careful with threaded compressor terminals, it's easy to stuff them up.
YES, scrolls MUST run in the right rotation. If you don't have a phase rotation meter, run the compressor ready to throw the stop switch. If it's in reverse, it'll sound like a bag of nails. More than a few seconds of that may damage the compressor.
Given that you're questioning the availablty of all three phases, I'd check that you have three phase incoming & that it's balanced. Don't bother checking the contactor. You should have replaced all the starting gear with the compressor as a matter of course - so do it now! For ultimate peace of mind, check the continuity of the new contactor before fitting.
Where did you charge the refrigerant - into the liquid receiver or straight into the suction?
Why did you charge less than you removed? How do you know the removed charge was right?
What current was the compressor drawing? Why is only half the evap. frosting? Which half? If there's a distributor then as Monkey Spanners says you may have a problem there. If it's a small system & there's no distributor, from your description my first thought would be short of gas for one reason or another.

I've probably left something out, hopefully others will fill the gaps.

[monkey spanners]

Scroll running backwards and then having phases swapped so it run correctly,

http://www.youtube.com/watch?v=hLXDb8jA-_4

[hyperion]

Some scroll compressors will wreck themselves in a short period of time when running backwards. Difficult to claim any warranty especially if the supplier has the can cut open to check the compressor.

[joe-ice]

I have seen several times scrolls that have run backwards for hours and were still ok after mains power came back after fault with rotation reversed. The big problem with scrolls i can see is at or near a vacuum they fire out their oil very quickly.If there is a pumpdown on this system dont let it get anywhere near a negative pressure on switching off.This can be an issue if low on gas as the unit is stopping and starting frequently near a vacuum its oil will dissappear.

[properdouble]

Hi
i checked continuity on existing compressor after failure. I was getting value 10 between all phases. System is a pumpdown indeed and has distrivutor evaporator was frosting on the bottom as it is searle coil box type divided in to 2 sections with def heater in the middle. I have charged less as i achived full site glass , i charged in to liquid recoever and then cleared site glass trough suction. Recievier is 7.2l so there coul be more refrigerant to go in site glass was full and then half emty and filled again so TEV was hunting. New contactor with overload will be installed as best practise. Connections are spade crimped to be honest i have no clue how it is possible to spark like this and yes pressure switch has to go back to original setting. Cannot wait to go and get it done and hopefully sort it out just one more question if it is distributor what can it be and can i fix it without replacing it perhaps blow it trough with ofn if it is restriction?
many thanks for all your input.

[mikeref]

Scroll running backwards and then having phases swapped so it run correctly,

http://www.youtube.com/watch?v=hLXDb8jA-_4

Monkey spanners gEpzXWE.jpg

[FreezerGeezer]

I have seen several times scrolls that have run backwards for hours and were still ok after mains power came back after fault with rotation reversed. The big problem with scrolls i can see is at or near a vacuum they fire out their oil very quickly.If there is a pumpdown on this system dont let it get anywhere near a negative pressure on switching off.This can be an issue if low on gas as the unit is stopping and starting frequently near a vacuum its oil will dissappear.

Or longer - there's a thread here somewhere mentioning a scroll that had been running backwards for about 6 months, iirc.
The thing is, the OP appears to be fairly new to this. So I was attempting to teach best practice & worst case.
Compressors in general are much tougher than we're taught at trade college. But there's always one that'll seize or blow as soon as you look at it.

[FreezerGeezer]

Hi
i checked continuity on existing compressor after failure. I was getting value 10 between all phases. System is a pumpdown indeed and has distrivutor evaporator was frosting on the bottom as it is searle coil box type divided in to 2 sections with def heater in the middle. I have charged less as i achived full site glass , i charged in to liquid recoever and then cleared site glass trough suction. Recievier is 7.2l so there coul be more refrigerant to go in site glass was full and then half emty and filled again so TEV was hunting. New contactor with overload will be installed as best practise. Connections are spade crimped to be honest i have no clue how it is possible to spark like this and yes pressure switch has to go back to original setting. Cannot wait to go and get it done and hopefully sort it out just one more question if it is distributor what can it be and can i fix it without replacing it perhaps blow it trough with ofn if it is restriction?
many thanks for all your input.

So you haven't meggered the windings or earth tested?
Spades can be a bit or even very loose, especially when they've been pulled off a few times. A squeeze with a pair of pliers on the female crimp sorts that out.

[joe-ice]

You should relax if you have the pumpdown on the scroll set for above 15 psi every time it knocks off that baby will run forever . If i had a fiver for every coldroom cooler i seen not distributing properly id be rich.You probably didnt help it on its way originally but thats how we all learned one time before social media took over.Was a lot easier to cover your tracks when i was training years ago dont give up the fight

[FreezerGeezer]

Good post Joe.
I agree about it being easier to cover back then, too.

[Grizzly]

You should relax if you have the pumpdown on the scroll set for above 15 psi every time it knocks off that baby will run forever . If i had a fiver for every coldroom cooler i seen not distributing properly id be rich.You probably didnt help it on its way originally but thats how we all learned one time before social media took over.Was a lot easier to cover your tracks when i was training years ago dont give up the fight

You forgot to mention "We" worked often in pairs, usually 1 knowing a particular subject better than the other.

Which meant both would learn, whereas now as soon as poss the "Improver" is charged out at Tech rates and expected to know it all!
Which is why this forum is brilliant for all!
Ditto Ranger!
Grizzly

[properdouble]

Hi Guys
Changed beast last week including TEV,this time i even put 1kg of R404a less than last time to achieve clear site glass and it run with temperature fine but still overcondensing. I came up with idea to put fan speed controller for winter months to make things more efficient. Thanks for all input.

[pie man]

Good to hear you sorted your fault, especially with replacing an expensive compressor changing the contactor, tev and drier defo covered yourself there! I went to a job a previous young engineer faulted a £1,000 compressor, turns out compressor was fine liquid solenoid was taking the breaker out....not good!