Engine Size: 6.4L
Refrigerant Type: R134a
Ambient Temp: 82
Pressure Low: 20
Pressure High: 180
Country of Origin: United States
So this morning, it being a Sunday; I decided that MAYBE my F350 service truck MIGHT need to have its AC serviced. Since it is 7 years old, and the AC is blowing ONLY 37F out of the vents when its about 90F and 90% humidity................it must need a re charge of refrigerant..........RIGHT???!!! Ok, so maybe I was bored and didn't want to tackle the 'Honey Do List' and wanted an excuse to get out of it. I pulled the gear out, checked vent temps, ambient air temps, pressures HI and LOW and proceeded to evacuate and pull a vacuum. My F350 specs say it takes 1.69lbs of R134a. So I recovered 1.50lbs of R134a, pulled a vac of 30in HG for 1 hr and then recharged w/ 1.50lbs of R416a (supposedly, your supposed to use 10% less of R416a/FR-12 for R314 systems). Upon recharge w/ R416 and letting system stabilize/equalize, my vent temps were now 47-50F (Way To Go Sh*thead!! You should have left well enough alone!!) So I then charged to 1.69lbs and then went back down to 1.50lbs, then down to 1.25lbs...............vent temps stayed the same, then got worse past 1.5 lbs. Anyway...........long story short. I evacuated and recovered the 416a and recharged to 1.69lbs w/ the R134a. Temps are now tolerable at 40-45F.............yeah, I was in a hurry 'cause the Queen was starting to buzz. 'We do it TWICE 'cause it's NICE!!'.........LOL!! I thought it was only going to be an hour to do that??!! Sorry honey, something must have gone wrong 'cause it's not working out the way I wanted. So NO, I did not have time to take the inlet and outlet temps at the condenser. It turned into to one of those 'OH YOU HAVE GOT TO BE KIDDING ME!!' situations. Hmmm, and now that I think about it, I may have skipped vac-ing out the charge line before I recharged the system w/ R416..........in between responding to 'DADDY!!!!!' and 'HONEY!!!!!!!!!!!'...........Note to selfo this stuff at work and not at home!!
So............anyone have experience w/ converting R134a systems to R416?? Should I have used a bigger orifice size or a smaller orifice when converting??
Yeah, I understand R134 systems were made for R134 and nothing else. I wanted to try something different, get the pressures lower on the HI side of the system and experiment. Next step will be to build a controlled system in the garage and experiment in a controlled environment. Same charge, same temp, different orifices, different TXV's and see what the vent temps and evap temps are.
Just reaching out to anyone who has played with this and see if they are willing to share their results and findings.
So upon placing this all into black and white while the rest of the household is now fast asleep and the peace and quiet have allowed me to digest the occurences of this morning, I believe I may have found the errors of my ways. I believe I shall take the time tomorrow, Monday AM; in the peace and quiet of the shop to delve into the dalliances of the R416a and their seductive allures.
37 degrees vent temp is wonderful, optimal, desired. hard to come by, fantastic, perfect, - so why mess with it?
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
Once the compressor starts to cycle, that will dictate vent temperature. Improving the basic performance of the refrigeration system will just cause the compressor to run less. Vent temperatures of 40 are the design point because any lower would require the metal of the evaporator to be below 32, and freeze-up will occur.
R-124 contains chlorine and has ODP, making it a "phase out" material like R-22. The price and availabilty of R-416 will get worse in the future.
Edited: Mon July 13, 2015 at 10:09 AM by mk378
So I put my truck back to its proper state w/ R134A. I recovered 1.18 lbs of R134, so I was short 0.51 lbs of R134 and I now remember that I didn't VAC out the charge line. I stuffed 1.70 lbs of R134 (spec is 1.69lbs) back into the truck, and VAC ed out my charge line before re charging w/ R134. AMAZING what the peace and quiet of the shop doth bring. (I can deal w/ the hub bub and questions in the shop. The Honey!! and Daddy!! cries I find a bit distracting!!LOL) Ambient is 80F, vent is 35F, and pressures 19-20 LOW and 145-150 HIGH. So I am back to where I started. I almost did start charging it w/ 416 but changed my mind at the last instant.
So my test subject for my R416 experiments will be my International 7400. Much easier access to everything and it uses an orifice tube, so I can dial it up a notch or down a notch fairly easily.
And that's a bummer to hear that 416 will be phased out. Guess I should buy a few more cans.
Also I would wonder about the suitability of using a chlorinated refrigerant with the uncapped PAG oil found in stock systems. When R-12 is mixed with PAG it almost immediately has a chemical reaction that turns it into sludge.
They market it as replacement to uneducated sheeple. I am glad you are doing your homework. Blends are produced to mimic the performance of the product they replace; and have a better fit in stationary applications. They tend to fractionate as one component leaks faster that the others in a mobile system (all mobile systems leak); this then changes the performance characteristics. Remember, the stock system is not designed to use a flammable refrigerant. Most tests I have studied or been involved with, ended in the "thumbs" down results. You can test all you want, but I would not waste the time or effort. This products legal use as an alternative come to an end as of Jan. 1, 2017 per EPA SNAP rule 20, signed and published July 2, 2015.
OK, now this is the feedback I was looking for!! Thank you for your insight and that makes perfect sense after seeing the make up of the R416. And your statement that all mobile systems leak is what I knew to be fact. Hence my desire to recover, measure, and then recharge my system. Even though the system was blowing cold I was wondering in the back of head how much charge remained since the truck is 7 years old (almost 8) and I haven't done anything to the system.
So what are your thoughts on using 416 as a replacement for R12?? Retrofit the system, flush the system, add the proper amount of PAG, and recharge w/ R134 and suck up the performance loss or use the 416 and understand that the blend will fractionate over time?? I guess each solution has its own pitfalls and its up to the individual to understand the benefits and detriments of each.
Thank you, HECAT; for that post. I'm sure other people will find that info of interest as well.
So I won't be tearing into the 7400 and testing out the 416 in that. Nice thought, though; of having much lower High side pressures.
After giving my 8 year old Silverado's A/C a shot in the arm, I've been getting 35ÃÂ° vent temps on high in recirculating mode, with ambient in the upper 70's to low 80's. The system never worked that good when it left the showroom floor!
I contemplated playing with this system too - flushing it all out and charging with R12. Lucky for me, I'm always too busy. I've come to the conclusion that the system WORKS, and I should leave well enough alone. Maybe when it grenades (it's a 21st century GM, so that could be any day now ...) I'll go that route.
Edited: Tue July 14, 2015 at 1:00 AM by jsmitty
Fact. From R-12 the retrofitting archives. Residual chlorine atoms remaining in the mineral oil would react with PAG oils to form sludge. Due to the chemical reactions, there was also some copper plating that occurred. Best to flush for retrofit, but the other crappy shortcut option (IMHO) that became popular was to dump POE on top of the mineral oil, due to much less reactions.
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