I decided to try to get an early start on the AC in my 74 Vette. I bought this in early October of last year with the AC not working. The unit seems to be complete with no apparent leaks. Everything looks dry, no signs of wet hoses or seals. The system has no pressure in it at all. The car only has 26,000 miles so there shouldn't have been any compressor problems at that mileage. Now I know that doesn't mean anything for sure, but I am trying to be positive! Yesterday I hooked up the AC gages and vacuum pump and pulled the system down to a 28 Lb vacuum, closed the gage valves and the system did not leak down, even over night so today I ran the pump for 3 hours to draw anything out from in the system. Now the question I have is, should I change the system over to R134 or use R12? I hate to use R12 and find out that the system doesn't work. If I go with R134 and the system works would you keep it converted or vacuum it out and go back with R12? With the interior being so small as a 2 seated car I am sure that R134 would be cool enough if the system functions. If the system doesnt function then there will be other things to consider. I'm not even sure I really have a need for the AC to work but it would be nice if it did! What do you think?


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Many people say that the R12 gets colder but I converted mine to R134 last summer under the expert guidance of Kyster, our resident expert at C3VR, and got excellent results. Now don't be fooled by the small cabin. These things generate a lot of heat from the engine bay, the heater core, and the exhaust. You can somewhat cure all of these heat sources. You need to ensure there are no openings in the firewall, insulate the floor under the carpet, and put shutoff valves in both heater hoses. These things alone knock down a lot of heat in the cabin. Sounds like you are well on your way. My advice is to convert to the R134. Hope this helps.

Scott

I agree with Scott...go for the full conversion to 134a, and insulate everything.

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Pull all that crap out and save 300 lbs!!!

If ya want comfort, buy a C6!

I got the clearance from the wife to pull all the AC stuff out of ours.  I'll keep it, of course, but out it comes if it ever comes back from paint!

UPDATE:
I charged the system tonight with R134. I only used 36 Oz of freon as I have read to only use 75% R134 of the required R12 original application. Compressor runs quiet as can be. Vents all seem to work. I guess the real test will be once the temps start going up outside which looks to be a while. I feel good knowing that is completed and I can move on to something else now. Next will either be an exterior detail or a motor detail. Not sure what I want to attack next. 

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Sound good. Even if you don't need it, run it occasionally to keep everything lubricated. If you don't, o-rings and seals will begin to shrink and the refrigerant will slowly escape. Preventive maintenance is the key.


Scott

Did you charge it without changing the oil in the system? 134 don't mix too well with the old type(R12) oil...if it don't mix, it don't carry the lubrication to all of the parts that need it. You need a different type oil in it for use with 134.
There are two kinds of oil you can use with R-134a. Ester oil will work fine mixed with a small amount of the mineral oil used with R-12. The other kind, PAG oil, will get contaminated with mineral oil and won't lubricate the system properly. Some say it also requires special seals, cause it'll make the old seals "wear out quickly"....don't know if I agree with that, tho.

There are A/C folks here that can give more info on this...Adams' Apple2007-04-12 19:20:58

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

[QUOTE=ranger3]Sound good. Even if you don't need it, run it occasionally to keep everything lubricated. If you don't, o-rings and seals will begin to shrink and the refrigerant will slowly escape. Preventive maintenance is the key. Scott [/QUOTE]

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�����
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MICK - C3VR Lifetime Member #113

I had mine converted to 134a and it is plenty cold in the summer.

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Well, here's my 2 cents from an A/C tech. I have retrofitted to 134a many of the cars I've worked on mainly when compressor, accumulator, etc. is replaced. However on the other hand I have charged just as many with R12. The real advantage of using 134 is the cost and availability. I have not had a problem at this point buying r12, and the price has gone done some as of late. I am in the business of fixing a/c systems, so I feel if the car is designed to use r12 then thats my first choice. If the system is tight who care whats in it. I have really not seen a drastic difference in duct temp. between the two. Because of cost I do recommend retrofitting cars that need to be charged once a year or so when the customer declines costly repair. Now as Joel stated. The most important thing is to get the proper oil in the system. I have used ester oil when just changing over to 134, but when components are replaced I use the vis. pag oil that the system requires. Pag oil does not travel with mineral oil, but from what I've learned a small amount of mineral oil in the system won't hurt. As far as orings and seals, yes the newer ones are made of neoprene. But my feelings are if the orings are not leaking don't worry about it. The only way the oil will get at the rings is through a leak. Well, Its more than 2 cents worth and I'm sure you all are as throughly confused as I am. Let me know if I can help. Terry

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Click on images for Before and After pics!

Thanx for expanding on the thought, Terry! I have converted quite a few systems on my own vehicles, and they all seem to work just as well, except the 'Burban, and it has rear air. It will cool eventually, just doesn't seem to cool as quick as it did with the R12.
I have to repair the system in the '74, sooner or later, as the comp. took a dump last year...so I will be switching it to 134 then.

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Now I have to add to this. I need to convert to 134a this year. I was in wallyworld yesterday and I seen a kit conversion that says that says that you don't need to crack the system to use this kit. Comments? Suggestions? Or, INSTRUCTIONS, simple instructions.

[QUOTE=OlrustysGhost] Now I have to add to this. I need to convert to 134a this year. I was in wallyworld yesterday and I seen a kit conversion that says that says that you don't need to crack the system to use this kit. Comments? Suggestions? Or, INSTRUCTIONS, simple instructions.
[/QUOTE]


RUN, FOREST.....RUUUUNNN!!!!!!!!
Don't fall for that one!

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Joel Adams
C3VR Lifetime Member #56    
My Link


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10-4 Joel. Yes you can buy so called conversion kits at Walmart etc. What it consists of is a can of R134 with sealer in it, and about 2 oz. of oil and an injector. First of all stay away from anything with sealer in it. I am getting cars in my shop that have been destroyed by sealer. Have it done by a shop that knows what their doing. As I stated above its a process to do it right. If your driving a beater its one thing, but if your talking about a Shark, don't do it. You know the saying, "if it sounds to good to be true,it is".

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Click on images for Before and After pics!

I've about given up on mine. I have no leaks that we can find, the pressure stays consistant, we can hear the fans in high mode with engine off, but when I go down the road the air coming out of the vents is a joke and the air is warm.

Ok , no wallyworld.

I like doing things myself, can someone tell me the right way? I'm a pretty good wrench and can follow instructions

[QUOTE=OlrustysGhost]I like doing things myself, can someone tell me the right way? I'm a pretty good wrench and can follow instructions[/QUOTE]

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Click on images for Before and After pics!

[QUOTE=warbird]I've about given up on mine. I have no leaks that we can find, the pressure stays consistant, we can hear the fans in high mode with engine off, but when I go down the road the air coming out of the vents is a joke and the air is warm. [/QUOTE] Are your suction hoses getting cold? If so you may need to replace heater control valve or replace with a manual. Terry

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Click on images for Before and After pics!

Warbird,
Terry is correct, If the compressor is turning, with the ac cluth locked, and the hoses are cold then you either have a problem with the duct system or the  heate rvalve is partially open, A cheap, non-complex fix is to install shutoff valve on BOTH heater hoses. This eliminates mixing cold air with hot air. NAPA has the shutoff valves.

Scott

When is comes to air conditioning, automotive or residential a quick fix in a can does not exist!!  OK, it may work for a while but not long term!! 

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Mel
Lifetime Member #90

 

[QUOTE=ranger3]Warbird,
Terry is correct, If the compressor is turning, with the ac clutch locked, and the hoses are cold then you either have a problem with the duct system or the  heater valve is partially open, A cheap, non-complex fix is to install shutoff valve on BOTH heater hoses. This eliminates mixing cold air with hot air. NAPA has the shutoff valves.

Scott
[/QUOTE]

My .02,

Does anyone have the NAPA numbers for the heater shutoff valves?  I'm without AC for awhile and in Florida it's getting pretty hot driving the last couple of days.

  660-1414
  660-1413


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Lifetime Member #73

The Money Pit.... and my niece

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The part numbers are 660-1413 and 660-1414.  The main thing is the size of the hoses.

Hi Terry

Check out this previous thread. It might help you narrow down the problem.

https://www.c3vr.com/forum/forum_posts.asp?TID=65274&KW=fan+relay&PID=237570#237570

Scott
ranger32007-05-13 08:18:25

[QUOTE=eurodesk]

Hi Terry

[/QUOTE]

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Click on images for Before and After pics!

Anyone ever use the r12 direct replacement like Freeze 12 or something of the like???  As I was always under the impression that 134a tends to leak out of "older" systems because of the hoses... that 134 needs teflon lined hoses...?? Fact or fiction??  

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StingrayJim
NCM Lifetime Member #1936

Stingray's '76���������������������������� StingrayJr's '78���������������������������Lil Red '94

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JimG & qurtz- Thanks for the numbers.  I got the valves yesterday.  Hope to get them in this weekend.

I would stay away from Freeze12. It is very volatile and could cause big problems in a front end collision. I tested it in a few fleet cars and it worked okay but those cars are now long gone.  As far as 134a leaking out moer than r12, I personally believe that is a myth. I converted my F150 and Vette to 134a and have had no problems at all. I needed to change the high pressure hose anyway so I didn't have an old hose concern. But the rest of the system is original and as previously stated...no problems.

Scott

 Eurodesk here: Thanks Guys eurodesk2007-05-16 05:32:23