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Old 05-04-2013, 07:27 AM   #16
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Re: A/C doesn't go on at all

If you don't want to put money into the vehicle, then do nothing, but you won't have A/C....

As already stated, most shops don't even deal with R-12 systems......I remember our last tank of R-12.......we paid something like 4X's the normal rate.....we repaired a vehicle.....used maybe 2#'s....about a week later I go to use it again, and I notice the tank is light.......the valve was shut off, but when soap tested, could see an external leak at the valve.....lost almost all of it.....owner was pissed, and we only did conversions after that....

You need to find the leak to do a repair, or it just will leak out again.....

If you have any kind of A/C experience, basically all you need is a conversion kit, and a vacuum pump, and a set of gages.....if you don't have experience, then have it done at a local A/C shop.....
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Old 05-04-2013, 03:32 PM   #17
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Re: A/C doesn't go on at all

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If you don't want to put money into the vehicle, then do nothing, but you won't have A/C....

As already stated, most shops don't even deal with R-12 systems......I remember our last tank of R-12.......we paid something like 4X's the normal rate.....we repaired a vehicle.....used maybe 2#'s....about a week later I go to use it again, and I notice the tank is light.......the valve was shut off, but when soap tested, could see an external leak at the valve.....lost almost all of it.....owner was pissed, and we only did conversions after that....

You need to find the leak to do a repair, or it just will leak out again.....

If you have any kind of A/C experience, basically all you need is a conversion kit, and a vacuum pump, and a set of gages.....if you don't have experience, then have it done at a local A/C shop.....
What is the best way to find a leak - without charging up the system with, as you point out, expensive freon?
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Old 05-04-2013, 08:02 PM   #18
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Re: A/C doesn't go on at all

There is only one best way.....add freon and a dye, run compressor and then using a black light you look for a visible leak......in some cases, the leak may be so small it takes awhile for the oil to leak out.....also, there are parts of the system that you can't see, like a pipe covered by insulation or the evaporator that is buried in the air duct work......for that a refrigerant "sniffer" is invaluable.....there are times when the leak is so small, that you may have to run the system, for a week, to find a trace of the leak....

If you are lucky, it's a huge leak, and easily found....
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Old 05-04-2013, 10:32 PM   #19
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Re: A/C doesn't go on at all

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There is only one best way.....add freon and a dye, run compressor and then using a black light you look for a visible leak......in some cases, the leak may be so small it takes awhile for the oil to leak out.....also, there are parts of the system that you can't see, like a pipe covered by insulation or the evaporator that is buried in the air duct work......for that a refrigerant "sniffer" is invaluable.....there are times when the leak is so small, that you may have to run the system, for a week, to find a trace of the leak....

If you are lucky, it's a huge leak, and easily found....
First of all, if I forgot to thank you for all of the help you provided. I really appreciate it.

I was able to test both sides of the line. The system is COMPLETELY out of freon. I guess there are two ways I can go from here:

1) Do a partial fill with dye and expensive R-12 and hope the leak is not in any place too nasty. I assume that since ALL the freon has left the building, it isn't a small leak.

2) Convert the system to R-134a. I understand that the cooling power of this mix is not as good as R-12, but the stuff is considerably less expensive. If I decided to go this route, what do you think about the conversion kits and the process? There are so many opinions on this that it is hard to know who to believe. I noticed that the "standard" conversion kit will not work on my car because it comes with the wrong high-side fitting, so I will have to get a different one. And what about the oil in the compressor? Do I have to suction that all out or can I use the existing oil? Do I need to change out any other parts or am I good with what I have? Also, where is the orifice tube? Might as well change that out with the system depressurized. These Haynes books suck.

J
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Old 05-04-2013, 11:07 PM   #20
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Re: A/C doesn't go on at all

If you do the conversion, replace the accumulator and flush out the system using a product for the occasion. Once the system is flushed, fully evacuate the system and then using ESTER oil, add the proper amount and then the proper amount of R134a.

On my 1988, the system holds about 2.5 cans of R134a. Note this is less than the R12 charge, due to the higher head pressure of R134a.
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Old 05-05-2013, 12:49 AM   #21
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Re: A/C doesn't go on at all

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If you do the conversion, replace the accumulator and flush out the system using a product for the occasion. Once the system is flushed, fully evacuate the system and then using ESTER oil, add the proper amount and then the proper amount of R134a.

On my 1988, the system holds about 2.5 cans of R134a. Note this is less than the R12 charge, due to the higher head pressure of R134a.
So would it be your recommendation to do the conversion, based on your experience, or to stay with the R-12? And since the system is completely depressurized, would I just suction the oil out of the compressor?
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Old 05-05-2013, 02:31 AM   #22
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Re: A/C doesn't go on at all

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So would it be your recommendation to do the conversion, based on your experience, or to stay with the R-12? And since the system is completely depressurized, would I just suction the oil out of the compressor?
The R134a is not bad, if you could get a larger evaporator (in terms of area) it would work better, but it's OK - and I use it in my car here in the Phoenix, AZ area.

You would need to run a flushing agent through the system to get as much oil residue out as you can, and when you do refill the system, do NOT use PAG oil - use Ester. PAG will result in the demise of your compressor.

This is what I used to flush my system last year when I replaced the compressor - linky. It would be wise to replace the orifice tube as well, it's inexpensive and a plugged orifice tube can ruin your day when you're trying to get the system working.
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Old 05-05-2013, 08:46 PM   #23
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Re: A/C doesn't go on at all

Silicon212, why the ester oil instead of the Pag? GM recommends the Pag......

Also it's recommended that the mineral oil be removed(and measured) from the compressor, and replaced with Pag......and then enough Pag oil should be added to the system.....typically 8 oz., total.....the rest of the mineral oil that is within the system, is compatible with the Pag.......like you say, the accumulator(with new desiccant) should be replaced......naturally, it would be better if the system was flushed of as much mineral oil as possible....but you will never get rid of all of it from the evaporator and condenser......

DO NOT USE CHEAP RETRO KITS! The valves will leak..........

formula for 134a is: multiply recommended r12 weight by 0.9......then from that, subtract 0.25 for the weight of r134a.......

for example......if the capacity of your r12 system is 2.0 pounds, 2 X 0.9= 1.8......then subtract 0.25 from that and you get, 1.55 pounds of 134a.....

The reason for this is to decrease head pressures.....but who has a sensitive enough scale for this? Only the expensive a/c machines do....

I would, personally, fill by pressure, using the appropriate graph of ambient temp and humidity.....

Unfortunately, most people don't have vac pumps to pull a vacuum on a system to do this job....I personally would let a shop do it......shop around....
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Old 05-05-2013, 09:41 PM   #24
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Re: A/C doesn't go on at all

PAG is absolutely incompatible with the R12 oil, and any trace of the oil used in an R12 system will cause damage to the system. Ester is compatible with both R12 and R134a systems, that's why the recommendation. PAG is only for use in systems that are R134a from the very start.
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Old 05-06-2013, 07:51 AM   #25
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Re: A/C doesn't go on at all

Well, I have to disagree that:

"PAG is absolutely incompatible with the R12 oil"

Especially in GM systems.....GM calls for Pag in their retrofit bulletins...
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Old 05-06-2013, 08:45 AM   #26
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Re: A/C doesn't go on at all

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Well, I have to disagree that:

"PAG is absolutely incompatible with the R12 oil"

Especially in GM systems.....GM calls for Pag in their retrofit bulletins...
I have to say that PAG oil / PAG 150 is for GM AC systems that NEVER HAD ANY MINERAL OIL IN THEM .

when converting an R12 system to R134 you use a conversion oil. ester oil is the correct oil. this chemically is compatible with the mineral oil. even with cleaning agents you will have some MINERAL oil trapped in the system. The use of PAG in this R12 system would result in what some call the BLACK DEATH .

When it comes to ac systems people from Arizona seem to be more educated about this stuff.. no room for error.

as was mentioned you put just a little too much R134 in on a R12 system in the AZ heat , the system will blow up...over pressure !

also remove ac compressor and drain out all the mineral oil. then add the ester oil into the compressor .

I believe the total system would use about 8-9OZ. put about 3OZ into the compressor refrigerant line connection ports. the rest in the NEW filter dryer accumulator tank ..
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Old 05-13-2013, 01:29 AM   #27
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Re: A/C doesn't go on at all

OK, I'm at the point where I need to clear the oil out of the existing original compressor. What is the best way to do this without buying another expensive machine? How much of a pain is it to remove the serpentine belt and the compressor to drain the oil? Is it necesarry to drain the old mineral oil out of the compressor or will 134a run fine with it? If it will run fine with the mineral oil in the compressor, do I have to add additional oil with the refrigerant when I put it in? Another couple of questions?

I notice that the line containing the orifice tube (after I replaced the tube with a new one) only seems to screw back to about 1/2 of the threads. Is this normal or should it go nearly all the way?

I got a replacement accumulator/dryer. It has 3 schrader valves (it's a carquest). One is obviously for the switch and one if the low pressure connection, but what is the 3rd one for? My factory unit just has 2.
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Old 05-13-2013, 07:20 AM   #28
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Re: A/C doesn't go on at all

OK, I'm at the point where I need to clear the oil out of the existing original compressor. What is the best way to do this without buying another expensive machine? How much of a pain is it to remove the serpentine belt and the compressor to drain the oil? Is it necesarry to drain the old mineral oil out of the compressor or will 134a run fine with it? If it will run fine with the mineral oil in the compressor, do I have to add additional oil with the refrigerant when I put it in? Another couple of questions?

Serp belt is easy.....then remove the compressor(you will need new seals....you lube the seal/o-rings with mineral oil, not Pag oil)....drain the mineral oil from the compressor, at the drain plug and at the inlet and outlet opening, while manually rotating the clutch.......rule of thumb is, capture and measure the oil out of the compressor....if less than 2 oz, add 2 oz to the compressor at the drain plug hole....if more than 2 oz, add the same amount....but you will be putting 8 Oz total of Pag oil to the system......then manually rotate the compressor clutch to lube the compressor...

I notice that the line containing the orifice tube (after I replaced the tube with a new one) only seems to screw back to about 1/2 of the threads. Is this normal or should it go nearly all the way?

Should go back to the same amount of threads before removal...

I got a replacement accumulator/dryer. It has 3 schrader valves (it's a carquest). One is obviously for the switch and one if the low pressure connection, but what is the 3rd one for? My factory unit just has 2.


Don't worry about it....just use the same two as your original....
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Old 05-13-2013, 07:30 AM   #29
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Re: A/C doesn't go on at all

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OK, I'm at the point where I need to clear the oil out of the existing original compressor. What is the best way to do this without buying another expensive machine? How much of a pain is it to remove the serpentine belt and the compressor to drain the oil? Is it necesarry to drain the old mineral oil out of the compressor or will 134a run fine with it? If it will run fine with the mineral oil in the compressor, do I have to add additional oil with the refrigerant when I put it in? Another couple of questions?

Serp belt is easy.....then remove the compressor(you will need new seals....you lube the seal/o-rings with mineral oil, not Pag oil)....drain the mineral oil from the compressor, at the drain plug and at the inlet and outlet opening, while manually rotating the clutch.......rule of thumb is, capture and measure the oil out of the compressor....if less than 2 oz, add 2 oz to the compressor at the drain plug hole....if more than 2 oz, add the same amount....but you will be putting 8 Oz total of Pag oil to the system......then manually rotate the compressor clutch to lube the compressor...

I notice that the line containing the orifice tube (after I replaced the tube with a new one) only seems to screw back to about 1/2 of the threads. Is this normal or should it go nearly all the way?

Should go back to the same amount of threads before removal...

I got a replacement accumulator/dryer. It has 3 schrader valves (it's a carquest). One is obviously for the switch and one if the low pressure connection, but what is the 3rd one for? My factory unit just has 2.


Don't worry about it....just use the same two as your original....
Like a dipshit I don't remember the original number of threads :P

I see a diagram for the serp belt but it doesn't say where to relieve the tension. I notice that to the right of the compressor is a round spring thing in a casing and below it is a pulley (I bet that's a clue), but there doesn't look like anything that I can put a 1/2 ratchet into and crank.
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Old 05-13-2013, 02:43 PM   #30
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Question Re: A/C doesn't go on at all

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OK, I'm at the point where I need to clear the oil out of the existing original compressor. What is the best way to do this without buying another expensive machine? How much of a pain is it to remove the serpentine belt and the compressor to drain the oil? Is it necesarry to drain the old mineral oil out of the compressor or will 134a run fine with it? If it will run fine with the mineral oil in the compressor, do I have to add additional oil with the refrigerant when I put it in? Another couple of questions?

Serp belt is easy.....then remove the compressor(you will need new seals....you lube the seal/o-rings with mineral oil, not Pag oil)....drain the mineral oil from the compressor, at the drain plug and at the inlet and outlet opening, while manually rotating the clutch.......rule of thumb is, capture and measure the oil out of the compressor....if less than 2 oz, add 2 oz to the compressor at the drain plug hole....if more than 2 oz, add the same amount....but you will be putting 8 Oz total of Pag oil to the system......then manually rotate the compressor clutch to lube the compressor...

I notice that the line containing the orifice tube (after I replaced the tube with a new one) only seems to screw back to about 1/2 of the threads. Is this normal or should it go nearly all the way?

Should go back to the same amount of threads before removal...

I got a replacement accumulator/dryer. It has 3 schrader valves (it's a carquest). One is obviously for the switch and one if the low pressure connection, but what is the 3rd one for? My factory unit just has 2.


Don't worry about it....just use the same two as your original....
OK, I got the belt off and the compressor out. Not an easy task as bolts are in odd spots. I see the oil quantity on the compressor. Question is: I replaced the evaporator and there was very little oil in the compressor. How do I know how much ester oil to add to each of those parts of the system?
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