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Old 12-08-2012, 07:09   #1
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134a Gas with pre 134a Evaporator

Hi folks, my 20 year old compressor died and the new compressor with 134a gas is not working right, are pre 134a evaporator problematic, should I have to change my evaporator as well,

Thanks

Michel
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Old 12-08-2012, 07:26   #2
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Re: 134a gas with pre 134a evaporator

Michel, all I can tell you is that my 26 year old Adler Barbour compressor also just died, and the mechanic said that I needed to replace my entire system because of the change from R12 to 134A. Other friends of mine said the same thing. Didn't know BOATT was spelled with 2 T's, for 'break out another two thousand'
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Old 12-08-2012, 07:38   #3
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Re: 134a gas with pre 134a evaporator

Many of the old R12 systems used a different oil than the 134a systems (mineral vs ester-based). These oils are not compatible and cannot be mixed. I don't know how completely an older evaporator can be cleaned of oil, but it, and the lines to/from it, would need to be cleaned of all mineral oil before switching refrigerant.

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Old 12-08-2012, 18:40   #4
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Re: 134a gas with pre 134a evaporator

Michel, explain what you mean in the best detail you can when you say “refrigeration not working right”. Performance is not a problem when using the old evaporator with a new 134a condensing unit. Forget what you have heard about 134a in a 20 year old evaporator previously used for an R12 system it is too late now. My only concern would have been age of evaporator. What is size of evaporator? What size speed resistor was installed in thermostat wiring? No resistor would cause the new variable speed compressor to operate at much less output capacity than the old unit.


Free Spirit, If mechanic said you need a new system because 12 volt Danfoss compressor would not run find a new mechanic. If after twenty years compressor runs but no cooling then it is cost effective to replace complete system if leak is in evaporator.
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Old 13-08-2012, 04:31   #5
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Re: 134a gas with pre 134a evaporator

Richard, thanks for your reply. On my system, the 15 amp fuse on the compressor appeared to have blown. I got 2 new ones, 1 to put in and 1 for a spare. Installed the fuse, turned on the breaker, and watched the amp meter spike to 20+ amps. Shortly after that, the breaker popped. Mechanic checked and said the compressor was locked up. Cooling had stopped sometime the previous day, judging by the temperature in the box. Really nothing wrong with the evaporator, although it had been icing up much more frequently than I'm used to.
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Old 13-08-2012, 07:48   #6
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Re: 134a gas with pre 134a evaporator

Free Spirit, Be careful of advice you receive, locked compressor armature on a Danfoss BD compressor will not trip breaker or electronic control module fuse. There was no way he could test for locked rotor and if he connected 12 volts direct to compressor it now will be destroyed inside. You had an electrical problem not a compressor problem. Correct troubleshooting when fuse blows is to check resistance of field coils and replace control module. Tampering and guessing is expensive.
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Old 13-08-2012, 16:33   #7
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Re: 134a Gas with pre 134a Evaporator

General info.
I recharged my boat standup fridge, A GE model from 25 years ago with r134a from r12

Needed to dump the mineral oil, literally, undid compressor and dumped it out.
Put in same amount of PAG about a cup and a half.
Kept everything else the same. It works.

I have read that the condensors on the air cooled fridges might not be big enough running the r134a so the fridge wont be as efficient. Evaporator should be fine.

My freezer now reads 6F when inside of boat is 90F, with r134a.
My feeling is the fridge runs more and if door is opened a lot gets warmer than it did with r12.

I added a filter strainer with a charge port for the low, and a bolt on tube charge port for the high side.
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Old 13-08-2012, 17:10   #8
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Re: 134a Gas with pre 134a Evaporator

134a is the common kludge. It can work. it will take longer to cool down the box on starting and it often will never keep the box as cold, or require 5-10% longer compressor runs to get it as cold. That's the good news.

The bad news is that you've violated federal laws, and any rubber seals in the system may or may not hold the 134a, the rubber used for it is normally different. The filter strainer is neither here nor there, but if there was a "drier" and you did not change it, you may have moisture trapped in the system which turns into acid and eats it out from the inside.

134a is the kludge, often it will work well enough for what you want, but it never will be 100% the same.

And R-12 is still only something like $50-75 per pound, odds are it wouldhave taken less than one pound to refill the system properly. The trick these days is that no one wants to work with R12 (lots of equipment to keep just for it) and they usually souble or triple the amount they charge you for, by using R12 to flush systems when they should be using cheap dry nitrogen instead.

Of course, if you didn't find and fix the leak...
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Old 13-08-2012, 20:14   #9
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Re: 134a Gas with pre 134a Evaporator

"The bad news is that you've violated federal laws"
Ridiculous! I am amazed you would say that.
I have also retrofitted cars from R12 to R134a

By the way, the different oils used DO NOT MIX. Any left over mineral oil after draining goes to the bottom of the compressor.

This guy here is talking about a system still charged with R12 and doing a switch to R134a. On mine the system had lost its entire charge due to the line rusting.

R12 based systems to R22or R134a system

Quote:
Hi there,
You can use the same compressor but the capacity will be lower.
In order to replace R12 with R134a the following procedure must be carefully followed:
1- Drain the system mineral oil.
2- Put appropriate synthetic oil in to the compressor.
3- Turn on the compressor and let it operate for a few minutes.
4- Turn off the compressor and drain the contaminated oil from the crankcase.
5- Again put new synthetic oil into the crankcase.
6- Turn on the compressor and let it operate for a few minutes.
7-Turn off the compressor and drain the contaminated oil from the crankcase. Test the oil for contamination with special test kit. If the contamination is less than 1% then you can recover R12 from th system.
8- If oil contamination is more than 1% then repeat from step4.
9- Change filter/drier,TEV, ...
10- Evacuate the system and change the oil again.
11- NOW YOU CAN CHARGE R134a.
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Old 13-08-2012, 21:14   #10
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Re: 134a Gas with pre 134a Evaporator

Odds are, there's been some violation in there. And while 134a is the generally accepted kludge, the EPA does not certify it as a drop-in replacement for R12. There are several gasses and mixes that will "work" to varying extents. If you didn't such down a hard vacuum on the system before you filled it? Problems. If you did suck down a hard vacuum? Are you sure it was just air in the system? No old residue of gasses, each requiring a different manifold and disposal tank?

Personally I suspect than manufacturing a whole new system instead of repairing an old one does MORE damage to the planet and I disagree with many of the regulations. I just point out in passing that if you don't know the laws and don't have the permit(s)...you've probably broken at least one of them. Like charging a system without first pressure-testing it to make sure any leaking has been stopped. And if any of those cars you retrofitted didn't belong to you? KaChing, you need a pemit to do that. It isn't hard or expensive to get, but if someone complains about the job not working, it could come back to bite you.

Apparently there's bigger BS involved. The production of R22 creates R23, and companies make big money from credits when they dispose of the far nastier R23. Guess what? I turns out a dozen big companies have been selling R22 really cheap, because they make their profit on the R23 they dispose of as a byproduct of making R22!

I personally couldn't care, just hope you "did it right" so the next fill lasts at least ten more years--which should be easy for any proper AC/reefer system.
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Old 13-08-2012, 22:16   #11
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Re: 134a Gas with pre 134a Evaporator

You know nothing at all.
I would say a lot more but what's the use.
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