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Thread: evap icing up
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29-05-2009, 06:22 PM #1
evap icing up
Hi guys
was at a job today where a third of the evaporater coil was iced up. it was a crafft package ac unit (window rattler)
there was too much heat in the room and this unit is struggling and is undersized.
My question is can some explain why the top of the evap iced up and what caused this.
i understand that the compressor will be permantly on as temp in the room will never be maintained but would like to know why it ices up as it did or why it ices up!
thanks in advance
moondawn
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29-05-2009, 06:44 PM #2
Re: evap icing up
Most probably, it has overworked, overheated, and now just beginning to lose its refrigerant charge. Soon it will be dead if competent urgent measures are not undertaken. Now it is necessary to switch it off.
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30-05-2009, 07:04 PM #3
Re: evap icing up
Filters, airflow and gas charge. Check all them and determine the problem. Also air flow on and off values.
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30-05-2009, 10:34 PM #4
Re: evap icing up
Add to that the high humidity of the UK for the realatively low temperature.... Had an LG that used to do that but it was easily fixed with a sledge hammer
No, Really... When I replaced it FOC (My fault for selecting the wrong unit) and replaced it with a Sanyo (I only ever visit that unit for regular servicing) I placed the LG on my drive and beat the daylights out of it Saying " You wont be doing that to me again" in a very Basil Fawlty way.... My neghbours are used to my little ways nowKarl
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31-05-2009, 05:35 PM #5
Re: evap icing up
hi all
thanks for the replies
the unit once defrosted, checked the system and it seemed to work well just could not cope with the demand. i just wondered why the icing would start cos its undersized. a walkthrough of how that process happens with a unit over working?
cheers
moondawn
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31-05-2009, 05:47 PM #6
Re: evap icing up
Were filters clogged or clean when you found the ice ?
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31-05-2009, 06:50 PM #7
Re: evap icing up
Your heavy struggling unit works with very large supeheat, compressor not cooled, heat gathers, head temp rise and rise.
HFC's molecules which are much less than earlier refrigerants's are bit by bit leaving the overheated system through the pores in copper pipes and loaded connections (even not speaking about the flair connections).
Evap icing up happens most offen at morning hours (if unit was left working). Outside air temp drops, pressures drop, at some moment evap pressure reaches such a low level (due to the lack of *****), that not only evap's coil - the return pipe may cover in ice. The process is aggreviated if, by that, the filter has been neglected.
If you do not measure suction pressure and superheat now soon you will lose your rattler.
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31-05-2009, 06:55 PM #8
Re: evap icing up
Due not to the lack but shortage of *****, of course.
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31-05-2009, 10:39 PM #9
Re: evap icing up
Filters were spotless mate.
the unit had been serviced recently and the engineer who serviced it noticed they had added more equipment into the COMMS ROOM.
Because of this the window rattler is overworking.
i aint sure that the unit is leaking refigerant more that it is undersized and therefor working every day every second of the day which odviously is not good.
cheers
moondawn
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31-05-2009, 10:56 PM #10
Re: evap icing up
Excessive load would tend to prevent the coil from frosting, not cause it to frost.
Insufficient airflow would tend to frost the coil evenly.
Insufficient charge would tend to frost the coil from the top down.
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31-05-2009, 11:00 PM #11
Re: evap icing up
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01-06-2009, 07:06 PM #12
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01-06-2009, 07:15 PM #13
Re: evap icing up
It would be more accurate to say that it doesn't have enough refrigerant in the low side of the system.
This could mean that the unit is undercharged... but it could also mean that the unit has a partial restriction, not allowing sufficient liquid to flow from the high side to the low side.
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01-06-2009, 07:56 PM #14
Re: evap icing up
Check the filter drier in the liquid line if it has one.
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02-06-2009, 12:12 AM #15
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02-06-2009, 02:36 AM #16
Re: evap icing up
is it 134a refrigerant per chance
mmm to beer or not to beer...........lets drink breakfast
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02-06-2009, 03:06 AM #17
Re: evap icing up
Short of gas
Last edited by Magoo; 02-06-2009 at 03:10 AM.
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03-06-2009, 10:29 PM #18
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04-06-2009, 03:12 AM #19
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04-06-2009, 06:09 PM #20
Re: evap icing up
not been back to site since.
will update if i go back
thanks all
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06-06-2009, 06:48 AM #21
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