cloudfather

Cheers Tech2
What I have researched so far suggests.
1. Drain oil from new compressor and measure it.
RockAuto has complete kit (Compressor, PAG 150 prefilled, receiver, condenser, orifice, high and low sensors, o-rings/gaskets. The Four Seasons brand HD6 style with two rear ports with single hose block, new hoses (3) is what I am considering and a new evaporator for the heat/cooling box.
2. Having problems identifying compressor, suspect it is a Four Seasons HD6 style old labels are not readable, but see HR6 also listed? which is correct? Are they interchangeable?
3. What I can find for 1995 G30 chev 5.7L is A/C stuff is 8oz PAG 150 (comes with compressor), and 48oz of R134a is this information correct I see lots of other answers? Dont want to over oil or charge.
4. I have UV kit several web sites suggest 1oz added to receiver or compressor. To insure not to over fill, suggests 47oz charge or 7oz oil?
5. I plan to use postal scale 1-64oz range to measure each can as I recharge.
6. Thinking recharge 50%, start engine, air to normal, max cool, then check for leaks. Then complete charge until low side is ~50, high side 150-185psi.
7. I did pickup vacuum pump 4cfm with matching gage set, connectors, UV and electronic leak sensor. I tested yesterday and they work as expected.

In the reading I see multiple approaches to recharge the system.
One says invert can and charge on low port, do 1/2 of the total, then connect to high port and repeat process,
Another says on new system recharge from just high port can inverted.
I understand the low side has liquid and high side should have gas. Need better understanding on correct procedure.

Am I asking the right questions?
Thanks again for great support.
Only had to drive 480 miles to get R134a.
But got to go to ham radio store and buy new toys
J

cloudfather

So parts arrived, few more questions.
For a Chevy G30 cutaway with 5.7L 1995 chassis: (Trade Wins 21 RV)
I see differing information on how much R134A and PAG150. One source says 48/8oz, others 22oz/8oz. Which is correct, this is just cab A/C no rear bitz.
This is a complete replacement of A/C system. Including hoses. Have digital scale to precisely measure R134a amount. With A/C on I think I should see 50psi on low side, 150-185 on high side once fully charged. Is that correct?

On the question of oiling, compressor comes with 3oz prefilled. If the 8oz total is correct we add 1 oz to compressor and 4 oz to low side manifold hose. Or 3oz is enough and add 5oz to manifold low side?

We plan to use UV dye, 1 oz seems to be the most common suggestion. Do we subtract -1oz from PAG oil or from R134a? Plan to add via yellow manifold hose to low pressure side.

Plan to mount up unit, etc. Then by hand rotate compressor 20 turns to pre-lube before adding R134a. Or do we need to add R134a first then hand turn the compressor to pre-lube it?

New compressor does not have port for 2nd high pressure switch, so will jumper across the old harness leaving single pressure switch on the accumulator.

Is the accumulator pressure switch normally closed, when system is not engaged, or is this closed with the R134a charge is high enough? See diagrams with both NO and NC markings.

I saw a suggestion to soak new seals in PAG 150 before installation. Is that correct?

The orifice tube, which end goes in first to the tubing? There are snap locks on one end.

What else am I missing, would like to get this perfect the first time. Writing myself a procedure to insure I don't miss things.

I am glad I did an autopsy on the old system, orifice was plugged solid, black junk in all the lines, compressor had broken valve spring on one cylinder, hoses were rotting, accumulator had holes in it. Only thing salvageable was condenser. Will reuse that on cold plate LDMOS power amp. Makes excellent 10KW CCS heat extractor.

My thanks to all who have provided information.
J Cloudfather

cloudfather

Was able to reassemble system, did vaccum to 30, left on pump for hour. Then closed manifold valves, to isolate pump from system. Let sit for 2hrs, was exactly same 30. This suggests system is not leaking.
Next we measured out 4 oz of PAG150 and added one oz of UV dye, put a funnel on yellow tube, filled the opened manifold value on low side, this sucked the mix into the sight glass, taking care to keep funnel full, and turn off manifold valve just before funnel runs dry. At this point we have 8 oz total oil+dye.
We started RV, let it come up to operating temp, checked serpintine belts, etc. All are quiet and correctly aligned.
Then set AC to MAX, fan to MAX.
The total required charge is 48oz or four 12 oz cans. We weighed each can when full, then after starting a slow charge to keep pressure good.
The low side gauge is 50-55psi, the high side is 30-40 after first can.
The AC Clutch has not clicked in yet. Let it side for 15min, no change.
Added can #2 low side added about 5 psi, similar to high side. Still no pressure switch engaging the AC clutch.
I stopped here, closed low manifold valve. Both now closed.

I suspect were not getting voltage to the clutch.
Tomorrow will warm up the RV
Then check if same psi is the same as day before.
Will check AC heater fuse
Measure from fuse block to switch in AC control panel for 12V.
Measure across AC pressure sw which is at 50+ psi. The question becomes should the pressure switch now be closed?
I did ohm out the new compressor, its low ohms 1.7 which makes sense for good part alternative would be open.
I also pulled AC switch plug and jumpered. No change still no clutch.
I did manually rotate compressor 20 times to insure oiling it has 3oz prefilled.
On the orifice, I lubed o ring with PAG 150, slid in the pipe with long screen in first, leaving the end with the tool nubs last in the pipe. Thats how the old one was. Did I install the orifice incorrectly?

So looks like mostly electrical problem, assumes orifice is install correctly.

Any other thoughts, Thanks to all who have helped.
J Cloudfather

cloudfather

Solved issue blown fuse in clutch circuit. Successfully charged system both low and high sides are right on spec.
Thanks everyone