R134a conversion - problem, or unrealistic expecations?

Moderators: Nacho, Tom Greenleaf, ACProf, acsource

Re: R134a conversion - problem, or unrealistic expecations?

Postby Nacho » Wed Jul 27, 2016 1:39 am

how much refrigerant did you add?
User avatar
Nacho
 
Posts: 2483
Joined: Tue Jun 28, 2005 3:41 am
Location: Hermosillo, Sonora, MEXICO
Favorite Refrigerant: R134a

Re: R134a conversion - problem, or unrealistic expecations?

Postby foamypirate » Wed Jul 27, 2016 4:52 pm

We added 2 oz.

I think I am going to have the system evacuated, and work with a different shop to charge it. My friend's hot rod shop is neighbors with an auto repair shop that has all the A/C service equipment. I am going to back the charge down to 26 oz, and work my way up. I think the first shop that charged it just threw 80% of the factory R12 charge in, had cool air at the vents, and called it good. They had it done awfully quick, so I don't think they did any fine tuning...
foamypirate
 
Posts: 10
Joined: Sun Apr 11, 2010 6:47 pm
Favorite Refrigerant: R12

Re: R134a conversion - problem, or unrealistic expecations?

Postby Tom Greenleaf » Wed Jul 27, 2016 6:37 pm

The right machine can just dial in an 80% charge just do the math. That isn't always the right spot.

Probably already said but only a couple left if that do ever do but when working (not now) would take up to a couple hours per vehicle to find the right spot. Some as low as 65% but none did better than a known 80% as that's the space it takes up at the pressures it works with if all else is known perfect as in like factory new.

That isn't the real world if even an all OE vehicle the perfect spot isn't just that simple. Nobody by the hour or flat rate is going to spend twice the allocated time or get paid to do so if they even know how.

It's not easy or fast. Put in what you think is 65%. Stop there and unhook all you stuff and take it for a ride if cooling at all you know at least oil is flowing. That will settle oil where it will be, cool off whole vehicle's metal so next fast pressure reading is much more likely to represent if low or more is indicated. Do the same again a little by a little. When/if depends on each day too you achieve the credible pressures and performance expected for the conditions then you have a real good clue you hit the right spot.

On some days when too cold or too hot (out of norms anyway) you are left with just guessing and it ends there.

Once in a while a vehicle just isn't going to work as well as another. Then you go looking for why or if it's a paid job how much is someone willing to spend if it's going to be a real hunt?

Perhaps with all this it's just right to find the person that will take the time for you to get the extra BTUs (British Thermal Units) to the max it can be OR know it's there now?

Tom
MetroWest, Boston
Image
______________________________
User avatar
Tom Greenleaf
 
Posts: 4541
Joined: Tue Jun 28, 2005 8:40 am
Location: Marlborough, MA. USA
Favorite Refrigerant: R-12+134a

Re: R134a conversion - problem, or unrealistic expecations?

Postby foamypirate » Thu Jul 28, 2016 5:42 am

Made a lot of progress today. We dropped the charge down to 26 oz, and things are WAAAY better. 90F, and even after extended idling, the high side was around 280-290 (still a bit higher than I'd like, but certainly better than 350-375). The HPCO no longer trips, even with about 1,500-1,800 RPM. The low side was 44-45. With the fan on max, and going down the road, I saw the vent temp dipping into the 46-48 degree range. Turning the fan speed down one notch resulted in 42 degree temps, and the clutch started to cycle. Once I finished my test loop, I popped the hood, and the whole accumulator was sweating, along with about 1 foot of rubber hose on the suction line off the accumulator. I think the charge is pretty much right on now. I might play with dropping the low pressure cut out just 1 or 2 psi to get that last little bit of cooling, being careful not to ice the evaporator, of course, but overall, MUCH happier with the system! I'm blown away by how small the charge is. I guess that PF condenser compared to the giant factory dual tube serpentine, and my shorter than factory hoses made quite a difference in system volume.

Thanks again for all the help and input!
foamypirate
 
Posts: 10
Joined: Sun Apr 11, 2010 6:47 pm
Favorite Refrigerant: R12

Re: R134a conversion - problem, or unrealistic expecations?

Postby Tom Greenleaf » Thu Jul 28, 2016 6:23 am

I don't suggest touching the LPCO at all now with these new results. Many are adjustable but leak after you touch them.

If you get a true 42F (it will still fluctuate some) stay there. You are better off with high volume of 42F than lower volume of a couple degrees less unless it's the same BTU power.

Now the hard part if this stays and works well right where it is do you want to find anyone who can still vacuum that out to the gram and put exactly that much back in and mark that as the known charge?

Think if mine I'd just leave it now. Expect some loss you will never find over hopefully more than a few years if still have this vehicle.

Archive what you know as time flies so you know what you did to get to this point if you should have to work on it again and call it quits and a success for now,

Tom
MetroWest, Boston
Image
______________________________
User avatar
Tom Greenleaf
 
Posts: 4541
Joined: Tue Jun 28, 2005 8:40 am
Location: Marlborough, MA. USA
Favorite Refrigerant: R-12+134a

Re: R134a conversion - problem, or unrealistic expecations?

Postby cornbinder89 » Thu Jul 28, 2016 5:28 pm

As you found, those orifice tube systems are real sensitive to amount, much more so then older types.
cornbinder89
 
Posts: 209
Joined: Sun Mar 22, 2015 9:10 pm
Location: Lyman, IA
Favorite Refrigerant: R134a

Previous

Return to A/C Questions and Opinions

Who is online

Users browsing this forum: Bing [Bot], The Google [Bot] and 7 guests