Flush it out with AC flush is the only way to get it all out.

 

I've flushed them with varsol before, but not sure it that'll get it all out of the compressor sump.

 

Flush solvent and LOTS of compressed air. Solvents like laquer thinner, MEK and others will work with proper precautions, but AC Flush solvent is always preferred.
Don't flush through any metering devices, the receiver/dryer or any hose with a muffler. It's best to remove the lines and flush each piece individually. The heat exchangers can be flushed in place.

For the compressor you need to oil flush the sump.
-Drain the compressor.
- Add a few ounces of the oil you intend to use.
-Spin the compressor a few times and drain the sump
-Repeat this 3 times letting he compressor drain as completely as possible the last time.
- Fill the crankcase with fresh oil from a sealed container. PAG oil absorbs moisture quickly so don't dawdle.

Good Luck.

 

I only flush the system if there has been a major failure that has caused debri to flow into the system. I just pull a vacuum on the system for 45 minutes and let it boil out. That way you should have all the old freon, oil and moisture out of the system.

 

Pulling a vacuum does not remove the oil from the lines and heat exchangers. The compressor also has a sump full of oil, like an engine. The OP is also converting from R12 to R134a which uses different oil.

 

I had my 1968 (cycling compressor) A/C system running on 134, just not cooling well. So I now have a new condenser, poa, pressure switch, dryer and the new style compressor. The sheet that comes with the compressor from Classic Auto Air says to flush the system, naturally, and rotate the compressor ten times by hand when recharged. When I spoke to CAA they said the clutch did NOT have to be engaged when rotating by hand. This I don't understand, but I can do it.
Also I mentioned that when I had the system apart, I had oil (clean looking) draining out (about 2 tablespoons) of the hose from the expansion. When I asked if the old oil had to come out, and if I could do it by flush, or blowing through the evaporator, I was told that because of the geometry of the evaporator that it had to be removed from the vehicle to flush out all the old oil and that's what they always do. If I had known this, I probably wouldn't have done so much upgrade. So I'll have to take it to an A/C shop so I don't invalidate the compressor warranty. Problem is finding a shop that knows what their doing with these old systems.

 

So I now have a new condenser, poa, pressure switch, dryer and the new style compressor.

The sheet that comes with the compressor from Classic Auto Air says to flush the system, naturally, and rotate the compressor ten times by hand when recharged. When I spoke to CAA they said the clutch did NOT have to be engaged when rotating by hand. This I don't understand, but I can do it.

You have a system with all new parts except the evaporator and hoses. There's no need to flush the evaporator, whatever is in there will stay there and not create a problem.
Just grab the front of the compressor clutch and turn it, no tools needed. The reason for turning the compressor by hand is in case there's liquid freon in it. Liquids do not compress, and if there's a slug of liquid R134 in the low pressure side of the compressor it will be damaged on start up.
The easiest way to prevent this is to evacuate the system and charge it through the high side without starting the car. However, you need a charging station that will automatically feed the proper weight of charge into the system, you can't do it with the 12oz cans.
BillL

 

Last one I converted I just put in a couple ounces of ester 100 oil and it works just fine. The R12 oil stays pretty much in the compressor since it doesn't mix with the R134a, and the ester oil is compatible with both R12 and R134a.

 

As per EPA 608 prep manual - ester oils can not be mixed with other type of oils. Than, again ester oils are compatible with HFC's as per HVAC fundamentals by AHRI. So it should be ok.

 

All you really need to do is draw a vacuum on the system for about 45 minutes add the appropriate amount of oil and charge the system. Any shop that can work on an R134 system can do the conversion. There is really no difference between the "old" R12 and the "new" R134 systems. They basically use the same components. I have never flushed any system that I have converted in my shop.

 

Thanks, but I still don't under stand why turning the compressor without the clutch engaged does anything. Isn't the pulley free wheeling and not turning anything internally?

 

They mean to turn the clutch not the pulley.

 

On an A6 compressor, you turn the very front black hub, not the pulley. You'll see an obvious difference in the two.

 

hi
Remove all components from vehicle
HAVE the evaporator fins been cleaned externally

****flush all components on bench WITH EVAPORATING SOLVENT [ shellite X55 hydrocarbon solvent ] or specialised flush .
,,pipes
,,condenser
evap core

new tx valve ,,reciever drier, R134a barrier hoses

compressor type ?? [A6 delco harrison ]
Have the compressor fitted with a new shaft seal and gaskets
Why because your going to use ESTER oil in the CORRECT amount
ESTER OIL
as with ALL oil in needs to mix with refrigerant to flow around the system
--mixed oils may not flow causing compressor damage
---CORRECT QTY OIL cools the best ***

good performance will be from
flushing and cleaning externally evap core
correct oil type & quantity

CORRECT pressures
EVACuation ,, new pump oil ,, [check gauges for connection leaks ],, evacuate for 1 ---2 hour minimum under 500 micron

CHARGE
always fill to 95% of weight charge ,, almost clear sight glass and reassess ,Cooling works best with 100% liquid refrigerant supplied to evap core . Gaseous mixture does not cool
to give best performance
subcool needs to be monitored around 10f is ok
super heat ,,t/x valve does this to prevent flooding liquid to compressor ,but over charge flooding can still occur

lowside average 29psi [freezing point ] anywhere between 20---40psi average is a good zone for performance . Not much u can do about this providing its charged correctly

High side as low as possible ,,
modern cars go as low as 60 psi
An older car keep between 150--200psi . [fixed displacement compressor]
How do u keep high side press down = fit bigger condenser / fit a modern parallel flow condenser
AND OR fit auxiliary 1 or2 electric fans 11,12,13,13,14,inch 20amps minimum

I run in my pick up 150--160psi high side pressures in full sun in 90 % humidity All doors open
110f--115f ambient 40f vent temp
second condenser with 12 inch fan fitted under rear bed

 

hi
Remove all components from vehicle
HAVE the evaporator fins been cleaned externally

****flush all components on bench WITH EVAPORATING SOLVENT [ shellite X55 hydrocarbon solvent ] or specialised flush .
,,pipes
,,condenser
evap core

new tx valve ,,reciever drier, R134a barrier hoses

compressor type ?? [A6 delco harrison ]
Have the compressor fitted with a new shaft seal and gaskets
Why because your going to use ESTER oil in the CORRECT amount
ESTER OIL
as with ALL oil in needs to mix with refrigerant to flow around the system
--mixed oils may not flow causing compressor damage
---CORRECT QTY OIL cools the best ***

good performance will be from
flushing and cleaning externally evap core
correct oil type & quantity

CORRECT pressures
EVACuation ,, new pump oil ,, [check gauges for connection leaks ],, evacuate for 1 ---2 hour minimum under 500 micron

CHARGE
always fill to 95% of weight charge ,, almost clear sight glass and reassess ,Cooling works best with 100% liquid refrigerant supplied to evap core . Gaseous mixture does not cool
to give best performance
subcool needs to be monitored around 10f is ok
super heat ,,t/x valve does this to prevent flooding liquid to compressor ,but over charge flooding can still occur

lowside average 29psi [freezing point ] anywhere between 20---40psi average is a good zone for performance . Not much u can do about this providing its charged correctly

High side as low as possible ,,
modern cars go as low as 60 psi
An older car keep between 150--200psi . [fixed displacement compressor]
How do u keep high side press down = fit bigger condenser / fit a modern parallel flow condenser
AND OR fit auxiliary 1 or2 electric fans 11,12,13,13,14,inch 20amps minimum

I run in my pick up 150--160psi high side pressures in full sun in 90 % humidity All doors open
110f--115f ambient 40f vent temp
second condenser with 12 inch fan fitted under rear bed

I think you just nailed once for all… Thanks!

 

Dave asked the question 13 years ago.
I hope he got it figure out by now.

 

oops

 

It’s still helpful information 👍

 

SWAMPY does add LOTS of technical color and precision! THNX again SWAMPY!

PS SSuperDave left TC as he thought we were all too 'woke'. Sure hope he didn't start huffin' that freon poor fella!? (is it anything like glue?)

 

With the summertime temperatures we have been having, this series of posts will never go stale. Its useful to people no matter how old the first post is.

Rick

Sent from my SM-G965U using Tapatalk

 

If hydrocarbon solvent not available
Use a specialized air conditioning flush typically available from auto air specialists /good auto parts store

The role of the flush is to act as a mild degreaser to remove chemical [oil]/debris contamination . AND because its a solvent it 100% evaporates leaving no trace of it ever being there .

It is highly recommended that the system be filled with nitrogen and released to remove the final traces of any moisture [system being open ] AND flushing solvent gas in system before the evacuation process starts .