foster r134a ref leak

[charlie patt]

have a foster prog 2 door full height fridge the cab keeps dropping r134a we nitro tested for 4 days at 140 psi no drop there.. its braised in test stub on lp and a hp drier with test stub and good caps no billet valve regassed after changeing leaking condensor dropped 40 percent of gas in one week went back and split test with nitro 150 psi on low side 250 on high side from friday till monday held good pressure reconected and gassed........ dropped pressure ten days later,pulled unit back to yard left on hp test at 250 with the smaller molicuel nitro/hyd mix 3 days later still no drop, system has been uv dyed but no sign of uv, its only a small system it has two fitted test point so the 134a is not being blocked by bad capiliary on the last test we even sealed the test points and no one had touched it there is no flare nuts new condensor and re evap coil have leak tested all of coils all pipework even the pins on comp no pressure drop at all any help? where the hell is it going? if i pressure at much more pressure i will split the evap when recharged unit pulls temp well and allpressures good and system has a good flow rate through cap hp drier changed with condensor

[install monkey]

ive had it on the accululator on the side of the evap inside-try an electronic leak detector!!more sensative.also check the 1/4 line on the re evaporation tray as it is coiled up and dirt can solidify blocking the view.

[charlie patt]

straight evap no acc no receiver either revap new but its hold pressure on nitro for days that is whats doing me head in

[install monkey]

during operation pipework expands and contracts and can loose gas slowly.an unapproved way of finding a leak is when its pressurised with a trace of r134a and nitro,set ur turbo torch onto a small flame and waft it over all component and u should smell the phosgene-best to wheel the cab outside for this to avoid fire alarms/permits etc.
is there a rotorlock valve on the compressor suction line.they corrode with condensaton and leak occasionally. have u tried an electronic sniffer?good luck

[install monkey]

last resort-remove all the fridge circuit and pressurise.then chuck it in the bath and look for bubbles!!

[charlie patt]

no rotolocks and we are useing a nitro/hyd mix with a small molecuell structure, we have pressured for 4 days with no pressure drop we have also uv system with no visable trace no flares either even a braised in drier i have had k40s that leak ref but not nitro on the plates but they are evaporating far colder but this evap cant get colder than minus 3/4 and no uv trace it holds aprox 650 gr

[install monkey]

have u tried regassing it and running with ur gauges left on .to prove the schraeder core isnt weeping.has the valve cap go a rubber seal inside? try swapping for a 1/4 gasket or bonnet and flare nut.-have does the capillary line run inside the suction pipe? they rub and create flat spots which are prone to leaking.-may be turbo torch time! good luck

[charlie patt]

caps are new with good rubbers and leak checked cap is external as it waxed when it killed a comp about two years ago

[Andy AC]

Wave a tek mate over the evap, I looked at one the other day with at least two leakage sites from deep within the finned section on the coil, system under 3 years old, already had replacement comp and controller, couple of condenser fans, almost completely rebuilt.

Andy

[install monkey]

have u tried pressure testing with helium?i take it youve seperated the coiled part of the capillary.if the fridge has had veg in then the smell of onions and citric acid can cause damage to aluminum. im 99% convinced its on the evap plate.
take the plate out and check the back of it.is there any signs of chefs manually defrosting after leaving doors open with the biggest cleaver in the kitchen.with all the time spent trying to identify the problem its prob about £90 for an evap plate from foster

[cadwaladr]

leak test it with a tek mate my guess is the evap my tekmate finds the smallest leaks,clear the entry hole into the cabinet area where the electrics pipes go to evap poke the tekmate in when its idle with 134a in the system shut the doors

[mikeref]

This has a good chance of being a temperature related leak. As install monkey says, expansion and contraction of pipes. Pressurising system will not show fault here as pipework is at workshop temperature. Have to isolate high/ low sides to two seperate circuits, and pressurise low side to (guess) 100 to 200Kpa and place in functioning chiller or very cold water. Lots of messing around with pressures but i'm sure pipe fracture will show itself. Fracture reseals as pipe warms up..Mike.

[joe-ice]

maybe you should try an ultrasonic tester picks up tiniest leaks ,let system run, plug out, then test when high side still hot and low side pressure rising

[charlie patt]

yesterday i split test low and high with the helium mix as of 8 oclock tonight no pressure drop thats been a 28 hrs test tomoz i will regas and sniff test it, i have removed the complete unit from top of fridge so its all in front of me to sea,if that dont work i will uv die again and let it run

[paddyaircon]

well what was it ??????????????????????????????????????????????
dont leave us with this cliff hanger, its like westenders lol
I reckon you have sourced the leak as a pinhole leak in the evaportor tubing. I have had this where the leak will only show up when dunked in water after sweating in a couple of schraeders each end of the evap.
aaaagggggghhhhhhhh fridge

[thebigcheese]

My moneys on the evap, change at least 1 a week

[mad fridgie]

Before your starting condeming coils, check the compressor terminals/pins cold and when hot.

[charlie patt]

we could not find it, we took the evap out and hp tested with nitro no leak and condensor no leak as previously suggested it had to be related to temp i was convinced evap and condensor was good as they had held perfect hp test even pulled evap out and hp tested at 300psi for 3 days with no pressure drop includeing comp terminals. no uv die anywhere so i changed the comp i did not no where to go next condensor was renewed recentley and evap was a whole week old ive kept the comp and will sea what happens ive fitted enough evaps and condensors in these units if they dont leak in a water tub they leak in the back of my van ovenight if i had apourous coil it would leak/ will the comp cure it? i will let you no

[charlie patt]

well afterfitting the comp i have not been back and customer is happy, i hp comp to 250 psi and it held perfect so i fitted it on a sales cab that was good and ran it for a week on day 8 it was pulling a vac and had droped 40 percent of refrigerant, it must be leaking on seal block on elec terminals sniffer dont pick it up and uv aint showing so just a update ta charlie

[simon@parker]

thats a slippery little bugger that have been changing about 6 evaps a month would have put money on it being that top info though will bear it in mind if i get one i cant find

[cadwaladr]

leak testing with helium is no laughing matter!