Aftermarket A6 with POA/R12 system

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Aftermarket A6 with POA/R12 system

Postby aquartlow » Sun Jul 24, 2016 8:47 pm

Just got through installing a 4 Seasons A6 replacement compressor #58096 in my '79 Ranchero (472 BBF install using components/brackets from a '76 Thunderbird). Man I missed having A/C in this thing. The stock A6 front compressor bracket fit great, the rear bracket had to be modified due to port location changes, instead of having just 2 bolts holding the bracket to the compressor body I fabbed the bracket to accept 3 of the 4 rear mounting bolts. I also used studs/blue Lok-tite on the top rear bosses so I wouldn't pull the threads out when tightening and used a much longer bolt with Lok-tite to locate the suction/supply lines to the rear of the compressor. I drained the PAG oil from compressor(about 2.75 oz), put in 3 oz of 525 mineral oil energized the clutch and turned the pulley to circulate the oil, I did this 3 times to get as much of the PAG out and/or dilute it as much as possible. I filled the compressor with 3oz of the 525 and installed it on the engine, I flushed the condenser/evaporator a few times to remove the old oil. I removed all the fittings where O-rings are to replace/lube them. Installed new expansion valve, all Schrader valves, new drier w/ O-rings, added 3 oz to pressure line going to input side of condenser, I removed the POA and tested it once again and re-assembled with new O-rings and placed 3 more ounces of 525 in the suction hose that goes back to compressor as well as 3 oz in the liquid line that attaches to expansion valve. Pulled a vacuum on the system and it got down to 26in hg and it stayed there for 2 hours after vacuum was turned off and removed. Plumbed R12 tank to system, cracked the supply line to gauges to flush the line with R12, turned tank upside down and let system take in about 3/4-1 pound of Freon, checked with leak detector and everything looked good, started the engine got it to 1350rpm and turned the compressor on as well as the dual electric cooling fans. It took a while for it to pull in the 4.25 lbs of refrigerant but it went smoothly. My exhaust is a bit noisey(dual 3" dumps and axle) but the compressor is quiet for sure and really doesn't seem to labor the engine in any way. After the Freon capacity was reached I checked center vent temps......34F with thermometer and 31.4F with infrared temp gun. It dang sure gets cold. I used a spray hose during the refill process to cool the condenser but the engine with both fans didn't crack 180F I also checked the pressures and the high side didn't go over 155-160psi the low side cycles between 19-25psi. Are these numbers good or should I be concerned and/or looking at or for something on the system that isn't right. Sorry for the long post, just absolutely excited to have A/C working once again. Thank you in advance, Todd
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Re: Aftermarket A6 with POA/R12 system

Postby Tom Greenleaf » Sun Jul 24, 2016 9:35 pm

Hi Todd - tough read all run on but think I got it. Up to you to fit compressor with brackets and seems OK just unsure what you meant much longer bolts and is that a problem where they went IN to wherever?

You have your performance but would recheck vent temps. You really can't keep it staying that cold or evaporator WILL ice up - not a maybe. You should notice if any reasonable humidity is doesn't make condensate now then floods ground or floor when you shut it all down.

IDK? Was new expansion valve pre-set or any info with it? Is it adjustable or what?

Low pressures consistent with low temps, strong air flow.

Vacuum to only 26Hg fine if at some altitude otherwise wonder why only that?

R-12 is the liquid gold of course and tolerates a LOT of being off some on charge but suspect expansion valve may have been set for 134a, bulb incorrect location or something.

Whole this is knowing the REAL vent temp and know it's probably as much as five degrees lower right at evaporator is only concern.

It's so old - good for you all around.

Owned a zillion rolling freezers on wheels all OE never touched and didn't keep way too long but tons of miles without hassle just a bit fuelish of course but very dependable cars not part truck and not sure I ever saw a '79 Ranchero? Not the point - cool and a Ford fan some of the time.
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Double check vent temps. Infrared thermos for me don't read air temps well or confuse mine. Note if frost seen with a good run or blower speed lowers flow depending on humidity.

BTW - If all is accurate if you held only a 26Hg vacuum even it suggests either wrong reading or you are at close to 4,000 ft. altitude?

It would work it not and probably fine with R-12 but why I just wonder,

Tom
MetroWest, Boston
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Re: Aftermarket A6 with POA/R12 system

Postby aquartlow » Sun Jul 24, 2016 11:46 pm

Once again, sorry for the long initial post, The long bolt I was referring to was the bolt.stud that goes through the plate that holds the suction/pressure kines on the back of an A6 compressor. I purchased a long metric bolt, cut off the head, made sure thr threads were good then using Loktite I threaded it into the rear of the compressor so I could use a nut to tighten the plate instead of relying on the threads in the aluminum body to pull the bolt/plate tight against the lines(probably no big difference but I have never pulled threads out of aluminum unless I was threading a bolt into it). I do have some older gauges so there may be a misreading, although my Ford manual says under 25 and as close to 30 as possible. I did do a leak check with my Matco detector and found none, so some good news. I have always heard certain POA's can be adjusted for differences in R12/134a never heard about the expansion valve differences, hope I don't have an issue. I will double check vent temps. I really didn't think the 31.4F was an accurate measurement, when the system was first installed using factory parts many years ago, vent temps were at 35-36F. The vehicle was inside a well ventilated warehouse and I was using water on the condenser as Freon was being charged, so there also could be a bit of difference. Tom, Thank you for the reply, much appreciated.
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Re: Aftermarket A6 with POA/R12 system

Postby cornbinder89 » Mon Jul 25, 2016 3:24 am

If you think about it, a Tx valve just looks at the outlet temp of the evaporator, and opens or closes based on the temp it 'sees". SO it shouldn't matter if the fluid is R12 or 134a, as long as it can open or close to regulate the outlet "superheat". Where it can make a difference is if you need to flow a whole lot more or less than the valve was designed for to get the temp right. Then a change in valve might be needed. With 134a or 12, the amount is fairly close so one TX works for either.
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Re: Aftermarket A6 with POA/R12 system

Postby aquartlow » Mon Jul 25, 2016 1:14 pm

I probably should have invested more time in researching all the pieces/parts that were purchased(I did not realize there was a difference in TXV calibrations). I never had an issue with the '76 parts except for the lower condenser's liquid line leak that caused all the parts replacement(just to BE SURE) after having a remanned A6 go bust on me I tried to cover all the bases. The TXV purchase was due to not wanting possible issues once R12 was charged(expensive of course). Other than finding NOS, I believe there is only 1 option for this TXV that uses a bulb and is externally equalized:
https://digital-assets.opticatonline.co ... 5338d7.jpg
I checked vent temps yesterday afternoon and after running the system about 3-5 minutes @ 1200 rpm, I viewed 35-36F vent temps, with no water sprayed on condenser.
Thank you so much for the reply Cornbinder89, hopefully the TXV difference isn't going to be an issue for me, just as you described in your reply.
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