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AC conversion R12 to 134a

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Old Jul 30, 2011 | 03:00 PM
  #46  
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Well, the charge can called for 50-55psi low side with the compressor running and an ambient temp of 100° I think I am going to look into getting everything from a r134 car then in the future and just doing a full, complete conversion.
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Old Jul 30, 2011 | 03:50 PM
  #47  
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Originally Posted by stockhatch
Well, the charge can called for 50-55psi low side with the compressor running and an ambient temp of 100° I think I am going to look into getting everything from a r134 car then in the future and just doing a full, complete conversion.
Seriously? They are sadly mistaken... There is a chart, perhaps that one even, that vehicle manufacturers use, and IMO, it is a total cop-out... I've never seen a perfectly operating R134 system go over 45 psi on the low side with the compressor on... I was always under the impression that the vehicle manufacturers put high pressures listed there to compensate for crappy a/c performance (when things aren't perfect)...

At any rate, if the only thing you have to go by is low side pressures, with the compressor running, I would shoot for 30-35 psi, give or take... The only completely 100% way to make sure that the correct amount of refrigerant is in the system is to draw a vacuum on it (completely empty it, then draw vacuum to get the moisture out), then refill with the correct amount...

I wouldn't give up yet... There is still a chance with what you currently have...
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Old Jul 30, 2011 | 06:42 PM
  #48  
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I will look into adjusting the charge. I want to say it was right at 30psi low side before I added refrigerant and it was not even blowing slightly cold.
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Old Jul 30, 2011 | 08:37 PM
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Originally Posted by stockhatch
I will look into adjusting the charge. I want to say it was right at 30psi low side before I added refrigerant and it was not even blowing slightly cold.
Remember, the compressor must be running, not just the a/c on as well... (I've seen many newer techs make that mistake!) Also, without a way to check the high side pressures, it is difficult to say one way or the other...

Might have a compressor getting a little worn out as well - that can cause high low side pressures even with the correct charge... would also account for why its not cooling as good as it might be able to if everything was perfect...
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Old Jul 31, 2011 | 08:17 AM
  #50  
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The compressor was for sure running, I made sure to check. I have gauges, but no r134 adapters so I cant check the high side I guess I do need to go ahead and get some...

I think I will just wait it out and source all the parts to convert fully. Maybe by next year I can scrape it all up, including a compressor.
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Old Jul 31, 2011 | 08:24 AM
  #51  
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Originally Posted by stockhatch
The compressor was for sure running, I made sure to check. I have gauges, but no r134 adapters so I cant check the high side I guess I do need to go ahead and get some...

I think I will just wait it out and source all the parts to convert fully. Maybe by next year I can scrape it all up, including a compressor.
Just pull the r134 adapters off
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Old Jul 31, 2011 | 09:53 AM
  #52  
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Yeah I guess that is an option. With the GTE in there, there is almost zero room to screw a fitting on the low side though. It is tough enough to pop a 134 hose on it. I may just pull the high side adapter and check the high side pressure. What should I be looking for on the high side at 95 ambient? Around 225-230?
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Old Jul 31, 2011 | 09:57 AM
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Yah, but if you see 250 - 300 I wouldn't be surprised in the heat with no airflow over the condenser...
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Old Aug 1, 2011 | 09:32 AM
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I've never taken off adapters before. As I unscrew them, will the system try to leak?
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Old Aug 1, 2011 | 09:39 AM
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And another question I have is will an Aristo compressor work, and would it be r134? It is off a 1997 JDM Aristo. It came with my swap. That may save me some money on a compressor.
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Old Aug 2, 2011 | 01:14 PM
  #56  
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Originally Posted by mitsuguy
Just pull the r134 adapters off
How does one get their system charged with r12 once pulling the fitting off?

Considering that you mentioned that most shops will stay far away from an r134 converted system?

I need to get my system filled with r12, as this r134 is not doing to well in the 100 degree heat.

Thanks in advance.
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Old Aug 7, 2011 | 03:33 PM
  #57  
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Well, I tried adjusting the charge to 35psi low side, but it still just blows cool and not cold. I also tried to pull the high side adapter, but they must pull the R12 shrader when they put adapters on because once I loosened the adapter up enough, it started leaking. I just tightened it back down and will wait till I get some r134 gauges.

I also replaced my heater control valve, so the core is not being fed hot coolant when the ac runs. It did not seem to make any difference.

Does anyone have any side by side comparo pics of the r12 vs r134 condensers? I am curious about swapping my condenser for the r134 unit.
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Old May 11, 2014 | 01:59 PM
  #58  
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It's getting hot here in NY, and my AC isn't blowing cold. Anyone know a reputable shop on Long Island that does R12 stuff? Also where exactly do I check to see if my AC has been converted to R134a? I know nothing of the stuff.
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