Sweep charge?

[spongebrain~~]

Hey guys, I just started working on "high end" refrigerators, and w/ R134a. Ive worked with 2 guys so far and they both handle the recovery and charging differently. One guy uses the "sweep charge" method, always changes the drier and then weighs the charge back in.

The other guy recovers the R134a through his manifold gauges and then uses a vacuum pump on the system. Then he charges through his manifold gauges until the low side is around 2 psi and the high side is around 125 psi.

2 completely diff. styles! I want to figure out what style is right, the best, the fastest, and in general which way will work best for me? Anyone have any opinions?

[NedFlanders]

I think one of those is probably illegal

[spongebrain~~]

Neither one should be illegal, they both deposit the refrigerant into a recovery cylinder.As far as I understand it, the sweep charge is the way that it is recomended.

[skpkey9]

Change out drier pull vacuum to 500 microns and weigh back in your charge. verify superheat and your outta there.

[k-fridge]

What we always referred do as sweeping was to purge the system with refrigerant. Many years ago this was actually recommended by Whirlpool when servicing their units. This practice is most likely illegal now, though it could fall into the gray area category depending on how much refrigerant escapes from the butt end.

Maybe the procedure you're referring to is something different.

[BigJon3475]

why not purge with nitrogen?

[nineball]

The first guy has been doing this for 35+ years

The second guy is doing it the legal way.

[skpkey9]

Refrigerant was used to clean the lines

[spongebrain~~]

you got it Niveball...................37 actually. Why would this be illegal? the refrigerant is being pumped into the cylinder because the compressor is running the whole time. The only diff I see is that its not getting vacuumed after its been recovered.........or.......am I missing something?

Does low side 2psi and high side 125 psi sound right at least? Also, can I use the same vacuum pump, gages etc. that I use for R22? Ive got conflicting info on this too from these two guys!

[skpkey9]

yes , you can use the same gauges and vacuum pump that you use for 22,
best practice is to use vacuum pump to insure no moisture or air remain in system. The tech charging by psi probrobly weighed in the first charge and looked where his gauge needles were and just started using that as a reference point.

[skpkey9]

oh ya and anytime that you open a system change the drier or install one.

[spongebrain~~]

All right.......sounds good. Do you think weighing the charge in is good enough, or should I slap the gauges on too? Actually, do you know where I can get some R134a info concerning these small fridge compressors online?

[yotaman16]

How would you be charging the system with out slaping your gages on?