91 Air Conditioning:Final question
Thread Starter
Drifting
Joined: Apr 2005
Posts: 1,283
Likes: 12
From: New York
91 Air Conditioning:Final question
I had the system evacuated of all the remaining R12, then I replaced all the O-rings along with the accumulator. Will R134A harm the compressor in this system, people at Advance Auto say NO, but I wanted to bounce it off you guys, THANKS!!
Melting Slicks
Joined: Mar 2003
Posts: 2,898
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From: Oklahoma City Oklahoma
You should replace the dryer (is that the accumulator?)
I had mine converted a couple of years ago on my 91. Been problem free, and I can't tell a difference between R134 and R12. It gets downright nipply in the car with the A/C on high!
I had mine converted a couple of years ago on my 91. Been problem free, and I can't tell a difference between R134 and R12. It gets downright nipply in the car with the A/C on high!
Thread Starter
Drifting
Joined: Apr 2005
Posts: 1,283
Likes: 12
From: New York
CMYC4GO, yes the dry is the accumulator, and I thought it was a good idea to replace it, so for $58.00 at Advance Auto, I went ahead, and replaced it. I have heard mention of the orifice tube, but I'm not sure where it is located, or if this system has it, or do all systems have it??
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
You HAVE to replace the orofices for R134 to work at all. They are located in the ends of the preassure hoses at the end.
you also need to change the two filling valves as the connection for the R134 will not fit the valve for R12
The new orofices and new valves usually come with the kit to convert to to R134 from NAPA
you also need to change the two filling valves as the connection for the R134 will not fit the valve for R12
The new orofices and new valves usually come with the kit to convert to to R134 from NAPA
Thread Starter
Drifting
Joined: Apr 2005
Posts: 1,283
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From: New York
JERRIS, that's interesting about the orifices. The kit I got from Advanced Auto had the two fittings, only one of which you need to fill the system which goes to the Accumulator. I'm still confused what these orifices do, I mean 134A, and R12 both convert to a gas at a certain temperature, and pressure. Do these orifices increase the line pressure as they are smaller, and do they slip into the lines, or do I need new line sets? I'm starting to think maybe I should go pay the $90.00 a pound for R12, and recharge the system as it left the factory.
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Le Mans Master
Joined: Jul 2005
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R-134 has smaller molecules than R-12. The orifice tube is a metering device that restricts the flow of refrigerant into the evaporator. This restriction is what cools down the liquid refrigerant by dropping its pressure thereby dropping it's temperature. The refrigerant comes out of the condenser very hot and needs to be cooled down before entering the evaporator in order to cool the air passing over the evaporator. Since r-134 has smaller molecules than r-12 it needs a smaller orifice. If you used the wrong orifice you could flood the evaporator with liquid which could reach the compressor and destroy it.
Last edited by mfi; Apr 23, 2006 at 04:47 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
You can replace the orifice, more so because as compressors wear, they shed a little bit of metal which gets trapped in the screen and that of course plugs it up. Reducing the R134 charge to about 80% of the R12 capacity takes care of any overcharging issues or better yet, charge until the high side reads about 2.2 times the temp of the air blowing over the condensor. You shouldn't have any problems doing it this way and you'll still have ok vent temps.
Thread Starter
Drifting
Joined: Apr 2005
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From: New York
MFI, I see the orifice tube in the inlet for the evaporator core, and was able to pull it out for replacement. The only problem I have is what to buy. The listing for this tube is assuming you are going to put R12 back in, which I don't intend to do. SUNCR's suggestion if filling the system to only 80% of the original capacity is correct. According to the instructions in the conversion kit, it stated to fill the system to 85% of the original capacity which would be 1.91 lbs. of R134A compared to the original volume of 2.25 lbs. of R12. They must assume the average person ISN'T going to change the orifice tube when doing this, hence the reason for not adding the full 2.25 lbs. Also with this kit, it comes with a gauge set the shows you exactly how much to add. So, once I get this back together, will see if I can actually have air-conditioning this summer.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Freeze 12 is 80% R134. Just know that if you mix 2 unlike refrigerants, there's a good chance of sending the high side pressure into the stratosphere and if the high pressure switch doesn't shut it down, you'll blow a hole in your hood. Thankfully, most people dump whatever they use into something that's completely empty, so it doesn't always turn out so bad and that's why we don't read about it the Obits.
As far as I know, there is only 1 OEM orifice for your Year and it'll work fine with R134. There is a whole host of aftermarket gadgets that may or may not work. Good a/c takes the right pressures. Go to the Board at www.ackits.com and you'll find good info on what is required for a conversion - you can even post a question if you're unsure about it. These guys do it for a living.
As far as I know, there is only 1 OEM orifice for your Year and it'll work fine with R134. There is a whole host of aftermarket gadgets that may or may not work. Good a/c takes the right pressures. Go to the Board at www.ackits.com and you'll find good info on what is required for a conversion - you can even post a question if you're unsure about it. These guys do it for a living.
Thread Starter
Drifting
Joined: Apr 2005
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From: New York
Thanks SUNCR, I have a nother problem now, the threads are messed up on the evaporator core inlet. So now it is either a new evaporator, or Advanced Auto sells a repair kit with a compression fitting, and it comes with a new orifice tube. That's what I get for working on this car after working a 12 hour day!!!
Le Mans Master
Joined: Jul 2005
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I'm suprised that the orifice would be the same for the 2 refrigerants. I had read something like the R-22 orifice was a .62 and the 134 was a .57. Not a big difference though. I'll see if I can find the site it was on.
Le Mans Master
Joined: Jul 2005
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I'm suprised that the orifice would be the same for the 2 refrigerants. I had read something like the R-22 orifice was a .62 and the 134 was a .57. Not a big difference though. I'll see if I can find the site it was on.
http://www.meekerauto.com/air_conditioner.htm
This has some basic info on it.
http://www.meekerauto.com/air_conditioner.htm
This has some basic info on it.
Thread Starter
Drifting
Joined: Apr 2005
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From: New York
MFI, I think your correct, there are two different orifice sizes, which is probably why they are said to only put 85% of the original factory fill in when switching to R134A. As I said above, I have another problem as the threads on the inlet of the evaporator core are messed up. I'm debating if I should use the repair kit, or just buy a new evaporator. We use compression fittings at work all the time, and they hold up to 800 psi, (semiconductor processing equipment) with no problems, so I might give that a shot. I would rather not have to pull the evaporator box off the firewall if I don't have to. Of course I would also rather not have freon leaking either. Anybody want a good deal on a nice 1991, I have fixed just about everything on this car including paint, and interior??!! Kidding, I have to much sweat equity in it to sell it now...
Le Mans Master
Joined: Jul 2005
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Originally Posted by KODAVETTE
MFI, I think your correct, there are two different orifice sizes, which is probably why they are said to only put 85% of the original factory fill in when switching to R134A. As I said above, I have another problem as the threads on the inlet of the evaporator core are messed up. I'm debating if I should use the repair kit, or just buy a new evaporator. We use compression fittings at work all the time, and they hold up to 800 psi, (semiconductor processing equipment) with no problems, so I might give that a shot. I would rather not have to pull the evaporator box off the firewall if I don't have to. Of course I would also rather not have freon leaking either. Anybody want a good deal on a nice 1991, I have fixed just about everything on this car including paint, and interior??!! Kidding, I have to much sweat equity in it to sell it now...
Try the fix first. You could always yank it. Keep an eye on it for a while after doing it.
Found this also:http://www.iroczone.com/projac03.html
Last edited by mfi; Apr 24, 2006 at 10:48 PM.
Thread Starter
Drifting
Joined: Apr 2005
Posts: 1,283
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From: New York
Thanks for the link MFI, I purchased the evaporator repair kit, it was only $21.00 so I'm not out that much. If it doesn't hold, I will just have to replace the evaporator along with a couple more cans of 134A. At least they aren't making a killing on the price of that yet. Advance Auto has cylinders for $21.00 each so I bought 3 of those as my Colorado uses 134A also, so it won't go to waste. Thanks again!!