pump down procedure

[Louis Cilento]

Does anyone have the manual for a Carrier Supra 844?"
or the low side pump down procedure for it ??
Thanks

[cadwaladr]

run it in cool mode and close reciever tank outlet,attach service guages prior to this of coarse.

[Louis Cilento]

Pressure still rises.. thinking im missing a step.. any other help??

[sedgy]

hi lewis ,
first calibrate your suction gauge , fit suction gauge to condencing unit< on suction valve< crack open valve if nessesarry , shut off discharge valve, run unit until suction is at zero, turn off, < L/P switch might stop unit it first< and pressure might build up after a few minits , so you might have to run it again
do not run it down on a vac,
if you are in doubt ask for assistance on site, sedgy,

[Northdude]

I had this problem and turned out to be the compressor, discharge on compressor was passing straight through to suction.

[sedgy]

hi northdude,
yes it dose happen , but I was indicating to louis, that after pumping down gas vapour boils off from the oil and the psi increases, , lets hope he dosent have the same prob , as you had , chears , sedgy,

[Tayters]

Hi Louis,

May be barking up the wrong tree but is there some type of oil return feed to the compressor still open thereby causing a bypass from high side to low side?
Did a search but only came up with the sales brouchure so for all I know it may not even have an oil separator. Closest thing I've come to in transport refrigeration is car AC .

Cheers,
Andy.

[cadwaladr]

whats the delivery pressure on this unit and the ambient temperature could be a week compressor,this would cause inability to pump down more info please.

[rizwankhan]

first u put mainifold both side and close the suction port ,start the unit and absorb the low side begin zero but remember that time lp/hp to be disconnected or reduce the value below zero.

[sedgy]

hi rizwankin,

sorry if you close the suction port how are you going to pump down?

[dimpanetas]

Hi Louis.I just saw your post.Check:
1.If your system has an electromagnetic valve in the suction line it has to close down at pump down operetion.But if it does not close properly the pressure in the suction line will rise.
2.If your system has a hot gas bypass valve,***** must not pass through it during pump down.
3.If of course the compressor has an internal problem ***** will pass through it from discharge line to suction line.
Hope to be helpfull