Problem with Tango: no service valves !!

[momo]

Been called to a Chinese Tango 11kW R22 Cassette A/C with 3ph Copeland compressor

Faults:
1.cuts out on freezing coil sensor bad or coil icing up according to local service call centre... to be checked.
2. leak from suction pipe.

Problem: this large (expensive) unit only has ONE service valve on the intermediate pressure! - located on the "liquid" line exit from the indoor unit :confused: (:D :rolleyes:)
Weighed in R22 to try acheive recommended pressure on line 8-10Bar ... could not acheive it, even when the suction line froze back past the suction tank to the compressor :eek: and refrigerant was past any reasonable charge :o.

On our next visit we will have to cut into liquid lines internally on unit and on suction line externally to see what's happening...

Due to difficulties with access and client times, fiestas :) etc visits to site are irregular, so:

A: Has anybody suffered any similar problems with this or other make's "cheapened"/simplified design and any other solutions?...

B: General practical question: When brazing a service valve into a 5/8" for the low pressure measurment:

Any comments about the angle and depth the 1/4 pipe take off point should have: if it the cut off faces flow will pressure be higher?, if it follows the flow will it be lower due to suction/venturii effect, therefore if square on will it be accurate... if so how much should poke into pipe?

Ultimately I suspect the compressor is worn out, but like any diagnosis without all the facts... before shocking the client about €€€€.çç.

[Brian_UK]

If brazing a fitting onto the pipe try this:-

Remove refrigerant, pressurise with nitrogen.
Braze fitting to outside of pipe.
Place small drill bit through centre of new fitting and drill hole into pipe.

Pressure within pipe should blow any debris out.

Replace schraeder valve core.

[momo]

Thanks Brian_UK - good example of professional practice for measuring the 5/8" line pressure.

[borodave1973]

If brazing a fitting onto the pipe try this:-

Remove refrigerant, pressurise with nitrogen.
Braze fitting to outside of pipe.
Place small drill bit through centre of new fitting and drill hole into pipe.

Pressure within pipe should blow any debris out.

Replace schraeder valve core.
Don't forget your safety glasses tho!

[The MG Pony]

Don't forget your safety glasses tho!

That or at least don't look down the hole while drilling!

[momo]

Battery powered drill on protected area of pipe, reasonable pressure (N2 is expensive here and big tanks same price so... :mad: and its a big long pipe) and bomb proof sun glasses :cool: - especially usefull when masoning out (demolition) for wall splits, or full face plate from angle grinding kit.
:) The demolition part: they don't tell you about when you train for refrigeration - plumbers suffer the same fate: glue, hacksaw, hammer, chisel, screwdriver, wrenches and bucket (for beers and omelette/sausage long roll sandwich :D) is your standard gear in this part of the world.

See new thread what's your standard grub (food) for a day on the site or road.