carrier split unit R22

[airconadam]

hi all got called to a unit today carrier wall mount split r22. Anyway it wouldnt cool when i looked at the outdoor unit it had burnt and melted through the cable on the contactor all the plastic shrouds had melted etc icheck the comp to see if it was down to earth but it wasnt, this unit also had a new compressor and contactor fitted about 7 months ago now i changed the contactor with an old one what was left on site fixed the cables and taped most of them up as they were so britle ithink due to the heat. The unit ran but the comp didnt sound happy at first the it ran and cooled no problem on the indoor,the pressure were 5bar on the suction ad 10bar on the discharge but the discharge pressure kept rising and rising untill it reached 38bar and then i turned it off, also when it was running i also took the amps the start winding was at 4 amps but the common and run went from 10amps rite from start up all the way to 20amp until a turned it off again ithink this is the comp on its way out any one have any other suggestions thanks alot

adam

model No-38gl024

[paul_h]

You were running thing on cooling yes?
5 bar is pretty high on suction, so removes restriction from the equation.
It was way overcharged after the last compressor change, or the compressor is stuffed.
Honestly, I would verify capacitors with a proper meter, verify the comp windings, check that the contacter is good (ie decent voltage to the compressor), then reclaim and weigh the reclaimed gas checking that it was the right amount before doing anything drastic.
If the capacitors are good, and the windings are good, and the reclaimed refrigerant checked out OK, then I would make sure there's no kinks in the suction line.

If everything is OK, then I'd suggest the compressor has failed and i needs a new drier and compressor.

[airconadam]

yer on cooling it did atually cool aswel when it ran but just not safe when running 38bar and it was increasing aswel. thanks alot

adam

[wambat]

Was the ambient air colder 7 mos ago? sounds like it was over charged, check the sub cooling after you remove some refrigerant and amperage and head pressure should go down

[frank]

yer on cooling it did atually cool aswel when it ran but just not safe when running 38bar and it was increasing aswel. thanks alot

adam

38 barg on R22

Somethings amiss and where is the HP control?

Burnt wiring is normally down to 1 of 2 things.

Loose connections or over current.

[airconadam]

ok thanks alot fellas will let you know what i find and still the comp sounds rough when it starts up maybe if its over charged it will do this??? thanks

adam

[airconadam]

exaclty what i thought frank ihave never seen such a basic unit to tell you the truth its just got a comp,coil,contactor,capacitor and thats about it really nothing eles inside it could of possibly caught fire thanks again

adam

[Brian_UK]

...I have never seen such a basic unit ...

Ah, the youngsters of today

Did anyone mention Marstair, IMI or similar

Seriously though, I would remove the gas charge and class it as contaminated; it could well be overcharged but it could also be charged with something that isn't R22. Weigh in fresh charge to be safe.

[airconadam]

who are they????? OAPS today

[Brian_UK]

Whipper-snapper, juts wait 'til I fire up the Zimmer frame and I'll be after you

[The Viking]

FIRST!

IF THE CABLE HAS OVERHEATED AND GONE BRITTLE IT HAS TO BE REPLACED, no tape, no shrouds, no excuse!!

Secondly,
I suspect you got non condensables in the system, that would explain the high HP.
The high HP would increase the running current BUT there should be a fuse or MCB blowing/tripping before the cables burn so it would be worth checking the protection.

[airconadam]

i totally agree viking but i only tapped them up just to see if it ran with the old contactor and now left the unit off at the isolator with it all disconnected and yes ther is an mcb or breaker but it does not blow first??? and to melt through an entire cable
thanks

adam

[superswill]

Ah, the youngsters of today

Did anyone mention Marstair, IMI or similar

Seriously though, I would remove the gas charge and class it as contaminated; it could well be overcharged but it could also be charged with something that isn't R22. Weigh in fresh charge to be safe.

there is still a few of them marstairs running like new on a site in grimsby,all these year with just the odd fan speed controller going and its the F gas laws that are going to finish them off

i may keep one in a glass case,iam quite fond of them little guys

[Brian_UK]

Oh Yes, can't beat a simple system can you?

C17 'stat, pressure switch (maybe), FSC (add on) a filter and away you go.

[knight rider]

i'm embarrassed to say i have well over 100 IMI 's / marstairs on one off the sites i look after, all running well ,ranging from 15 years old to 6 months . dont ask my why they like installing this piece off ****.
is there any one eles out there install IMI

[superswill]

Oh Yes, can't beat a simple system can you?

C17 'stat, pressure switch (maybe), FSC (add on) a filter and away you go.

sometimes less is more,why overcomplicate these things,dont get me wrong i love VRV's but somedays its nice to go out to one of them "back to basic" units and shed a tear as by 2010 its the scrap yard in the sky for them

[airconadam]

hey fellas decanted the unit today and recharged but still the same only afterwards ithought possible blockage any suggestions??
thanks alot

adam

[frank]

i totally agree viking but i only tapped them up just to see if it ran with the old contactor and now left the unit off at the isolator with it all disconnected and yes ther is an mcb or breaker but it does not blow first??? and to melt through an entire cable
thanks

adam

Adam
If the cable is rated at less than the MCB then you have a problem as it should be:

MCB is rated in excess of but close to the load
Cable is rated in excess of the MCB

So, if your cable is showing signs of overheating but the MCB doesn't trip then replace the cable with at least the next size up.

What is the running current and what size MCB is fitted?

I've been to an old IMI unit before where the L'unite compressor was running away lovely but the indoor was not cooling very much, but you could hear gas/liquid whoosing through.

The problem was found to be the condenser fan. Someone had been to it, and replaced the condenser fan motor. Problem was, they had fitted a clockwise motor instead of an counter-clockwise fan.

Does the unit have capillary control?

[airconadam]

not to sure about the capilliry control i condemed the first compressor on this and this unit would run fine and cool but then after a few mins the amps wud go through the roof and go off at 80amp but went to 80amp really really fast ie 20,30,40,50,60 etc and this would then trip the mcb?? ialso found out today of one of the maintenance guys on this site that this unit,by another firm got recharged with r407c by an accident and ran up think i just opened ican of worms thanks alot

adam

[airconadam]

anyone? think youve all gone to sleep

adam

[munya72002]

hie. offcourse the backpressure is high but since it was running like that all along there must be something else wrong now that is causing a problem. i think the H.P side has a small restriction that is why the pressure is going up after a while resulting in excess load on the compressor causing it to demand more current from the supply hence burning contactor terminals. the unit might have been contaminated when that compressor was installed 7 mnths ago. usually the blockage occurs in the capillary tube or filter drier. could you remove the filter drier and capillary tube then you clean the whole system with pressurised nitrogen and then you put a new capillary tube and filter drier. i think it wil work. if it doesnt then the compressor is about to cease replace with a new one. run the system at a back pressure of 65Psi or 4.40 bars. good luck!!!!!

[airconadam]

hey fellas the unit was a capillary. After replacing all the cables etc etc and testing for any blockages which none were found,i recharge and ran the unit same again the pressure were going up through the roof then suddenly the comp stoped when i checked the resistance there was none.So the comp has now gone but still there must of been a problem somewere eles?? anyway i think we now going to fit a new Daikin unit not one of these OAPs units

thanks alot fellas

adam

[Brian_UK]

You might find that the comp is open circuit on an internal klixon.

But, to be honest, after the unkown history and the bits that you have found out it would make long term sense to condemn the unit and get it replaced.

Some expense to start with but cheaper running costs than before and a new lease of life for it.

If all else fails, throw it off the roof

[airconadam]

hehe iwill tommorrow

[Mohammed Qasim]

Hi
All above reasons are true and it could be the cause,but please check the outdoor fan speed in your way.
thanks