split system Frozen suction line

[phs]

hi guys im new here thought id start by saying hello.

iv come across an a/c issue at a friends place . this is the problem

frozen suction line

once you start it u get about 5 degrees temp difference over the indoor coil, after it freezes up (about 15 mins) temp. difference drops to only 1.5 deg.
i had the gauges on it. closed about 900kpa. open about 100kpa. gas r22.

any idea of course ?



http://farm6.static.flickr.com/5100/5457737427_7965a552c9.jpg

[AWAIS MAZHAR]

Hi
First you check gas pressure it must be 60 to 65 psi
if u have then you check blower speed and coil. if coil are not clean then problem might be there.
and secondly check blower fins and make sure that they must be clean.

[joe magee]

1st Air filter. 2nd blower speed,belt etc. If that checks ok then hook up the guages.

[monkey spanners]

As the others have said, air flow and filters. Then i would be looking to see if it is short of refrigerant, which as it looks like a split you can only tell by weighing the refrigerant charge out and back in again.
Another possibility is if the outdoor temp is low and there is no low ambient speed control on the condenser fan motor.

Jon :)

[phs]

Sorry I had a look today it's the liquid line that has frozen

[paul_h]

That photo in the OP is suction line though.
In cooling mode with an ambient not low temp:
Smaller liquid line frosted up means short of refrigerant or outdoor capillary/TX restriction.
Larger suction line frosted up mean poor airflow through the indoor or suction line restriction.

edit: That a/c looks weird, the top service valve and piping looks bigger than the lower valve and piping. But it's the smaller looking service valve at the bottom that has the gauge port. I know the frost is making the top valve and piping appear larger, but the bottom only looks like 1/4 or 3/8" :confused:
Brand and model?

[monkey spanners]

Sorry I had a look today it's the liquid line that has frozen

If its got a frosty pipe then its evaporating at too low a temperature.

So think of hings that would cause that,
Low load (dirty coil/filter/fan blade/fan speed/low head pressure)
Low refrigerant charge (leak/undercharged/even wrong type of refrigerant)
Restriction to refrigerant flow (blocked capiliary/shut service valve/clogged strainer or drier (i have seen these block up when refrigerant tries to go through but flow fine with nitrogen!))

Jon :)

[phs]

That photo in the OP is suction line though.
In cooling mode with an ambient not low temp:
Smaller liquid line frosted up means short of refrigerant or outdoor capillary/TX restriction.
Larger suction line frosted up mean poor airflow through the indoor or suction line restriction.

edit: That a/c looks weird, the top service valve and piping looks bigger than the lower valve and piping. But it's the smaller looking service valve at the bottom that has the gauge port. I know the frost is making the top valve and piping appear larger, but the bottom only looks like 1/4 or 3/8" :confused:
Brand and model?


yeah the bottom line is the suction with the service valve 3/8th the top one is the liquid line 1/4" it looks much bigger cause thats how much frost on on it ... i have a feeling its a blockage there are no leaks . its a cheap homemaker unit. 2.5 kw's

[phs]

and its on a caravan

[paul_h]

I know all about cheap homemaker splits, I have 3 x 3.5kW :)
Been pretty reliable for me ;)

If you haven't done any pressure testing or lost any refrigerant, best way forward to to do a reclaim and weigh.
IE a long reclaim and heating up the compressor and accumulator to get all the refrigerant out, obviously recording the weight of the reclaim cylinder beforehand so you can get the total reclaimed weight.
If the weight is equal to the factory charge, then you have a restriction and no way to repair but to replace the strainer and capillary (no idea if you can get these parts, but the homemaker brand is made by AUX in china)
If however the weight of refrigerant is low, then life is easier, you just have to find and repair the leak.

[phs]

Iv hooked the gauges on 900 kpa closed once opened it drops to 100 kpa .. There are no leaks .
What is the average temperature drop over the indoor coil ??? 7 -10 deg. On high fan setting ?

[monkey spanners]

Have you weighed the refrigerant charge?

[paul_h]

Iv hooked the gauges on 900 kpa closed once opened it drops to 100 kpa .. There are no leaks .
What is the average temperature drop over the indoor coil ??? 7 -10 deg. On high fan setting ?
10-20 deg depending on humidity

edit: Also stop closing the SSV while the compressor is running.
100kPa whiel running is low, we get it. You either have restriction or shortage, and weighing out after reclaim is the only way to know for sure

[Gary]

once you start it u get about 5 degrees temp difference over the indoor coil, after it freezes up (about 15 mins) temp. difference drops to only 1.5 deg.
i had the gauges on it. closed about 900kpa. open about 100kpa. gas r22.


I'm betting you are measuring your temperatures far away from the evaporator coil. If you measured the temps close to the coil, the dT would be much more substantial, indicating a lack of airflow... probably a dirty coil and/or dirty fan blades.

But then, I'm just guessing... I can't see it from here. :)

[phs]

I'm measuring the air temp in deg. Cel. Not F. 10c. Is 50F

[phs]

I'm measuring right in the out let

[phs]

10-20 deg depending on humidity

edit: Also stop closing the SSV while the compressor is running.
100kPa whiel running is low, we get it. You either have restriction or shortage, and weighing out after reclaim is the only way to know for sure what is the ssv ?? I thought 100kpa was low. I'm not going to re claim it as my reclaimer is full . I was only courious to the cause .. Thanks for your help

[jbomba]

open the outdoor unit and see if you can find the part where the frost stops will usually be a strainer of some sort. where the frost ends is the start of your blockage

[lawrence1]

Is the suction valve fully open?

[baycuclaudyu]

Hello ,
First of all, try to discussed with the costumer about the history of this problem .If is happening when they start-up the split ,probably the problem is becouse the suction pipe is throttled .
Another issue is outdoor temperature .
Check that .

[paul_h]

LOL stop bumping this thread.
Some random guy that bought gauges, or is an apprentice doing a favour but doesn't have all the required tools or knowledge and probably won't ever be back asked a question that was answered.
Maybe not going to come back because he is not in the trade, just owned gauges.
Evidence:
he wasn't sure 100kpa was low for R22 in a split system
didn't know what a SSV was and was closing it for testings sake
reclaimer was full so they weren't prepared to reclaim and weigh? Mine's always empty, I use it to fill reclaim cylinders, not the reclaimer itself. But anyway, when it came to a reclaim and weigh, they bugged out not wanting to go that far, could be due to equipment or qualification, either way, they were out of their depth and I doubt they had a reclaimer.

[phs]

ok paul_h you must know that im a im fool with some crappy gauges good for u!!!!
this is a trouble shooting forum, which i posted on.... i am qualified to do the work.
i was asking cause id like to learn more. i could'nt reclaim gas cause it was at the time FULL.
i currently do not have time to go back and do it. i was only trying to get an idea of possible problems i personally thought it was a blockage. i dont do much service work at all unless its for friends, nor do i do much a/c refrigerant work at all. but im not going around try to make a living off it either, this job was for a friend i didnt put it in, only trying to find out for him if it is worth trying to fix. when i have the time...

ur attitude stinks if u think all of what u had written above why bother writing at all ???
its beyond me u would waste more time to make your self look good and put me down than just help answer the question. or just not post anything at all...

if you want only experts posting on here well be specific and say so.

As for every one els thanks for your responses, ill endeavour to get on top of this when some spear time comes up. unfortunately its not just up the road ...

i do appreciate your posts

cheers.

Jbooma:
cheers i was going to give that a go.

lawrence1 (http://www.refrigeration-engineer.com/forums/member.php?27492-lawrence1)
yes it is fully open and back seated.

(http://www.refrigeration-engineer.com/forums/member.php?25440-baycuclaudyu)
(http://www.refrigeration-engineer.com/forums/member.php?25440-baycuclaudyu) baycuclaudyu (http://www.refrigeration-engineer.com/forums/member.php?25440-baycuclaudyu)
it starts, cools ok for about 5 mins then trails off within 30mins of starting its only cooling 1.5deg cel. lower than inlet temp. on average working correctly 10deg. cel. temp differance over the coil is good.

thanks guys..

[baycuclaudyu]

When is start to have this problem ?
Is working in the winter with the condenser fan on full capacity ?

[phs]

summer time, is when i hooked the gauges up to it. both fan's are working fine i have checked for leaks with current charge cant find any.

installation was about 3 years ago working fine till now.

the reason im keen to find out is its on a caravan im curious to know if the fact thats is getting knocked around might have something to do with it.

as far as the frost goes it just keeps on frosting thicker and thicker for hours.

if it was low on gas would nt shut down ? i thought splits have safety so when the gas it low they shut down ?

[baycuclaudyu]

As I undrstand ,condenser unit is on the top of caravan ,the pipes are short ,and you don't have oil trap ?
Compressor is start to make more noise ?

[paul_h]

nor do i do much a/c refrigerant work at all. but im not going around try to make a living off it either, this job was for a friend i didnt put it in, only trying to find out for him if it is worth trying to fix. when i have the time...

So I was right.


ur attitude stinks if u think all of what u had written above why bother writing at all ???
its beyond me u would waste more time to make your self look good and put me down than just help answer the question. or just not post anything at all...

I spent time telling you how to fix, and you said the system is just going to be replaced instead, wasting my time after I did tell you that you need to reclaim and weigh.
After you said the unit will be replaced, I was just telling everyone else here not to bother. Pretty sure you said earlier that your friend decided on a new system?
Otherwise you just need to reclaim and weigh, nothing is going to change that.

[phs]

paul_h : look i give up i dont care for this keyboard warrior stuff, life goes beyond my keyboard.
what do u care if people are asking more questions, im keen to discuss it with them.

[phs]

the condenser is one the A frame section at the front of the caravan. so not on the roof. the pipe travel across 0.6meters then up the wall of the caravan 2meters to the head unit, the compressor sounds normal. no oil trap.

cheers