Air Conditioning Band Aid
Thread Starter
3rd Gear
Joined: May 2019
Posts: 3
Likes: 0
Air Conditioning Band Aid
Hello Everyone,
I just bought a 1968 convertible this January and i'm really excited about it. It has alot of options, one being the AC - which of course doesn't work.
It has the L79 327/350 and i plan to do some work on the top end to get it up to around 420, however that won't be until the driving/show season is about over. The problem is that I live in South Georgia and its HOT. I would really like to have some AC blowing, but i don't want to pay alot of money to then turn around and have to let all the R-12 out when i redo the motor.
I was wondering if it is "safe" to use something like AC Pro just to hold the system over until i dress the engine. I know AC pro is R-134A and it can cause some seal leakage, but the question is will that permanently damage the seals? Or will it just cause the AC Pro to not be as effective?
If it just ends up being moderately less effective, but overall not damaging it would bring some much needed relief. If it does cause damage I might just have to suffer because I don't want to have to rebuild the system, although that is a possibility regardless.
If anyone has some wisdom they would like to share i'm all ears.
Thanks,
I just bought a 1968 convertible this January and i'm really excited about it. It has alot of options, one being the AC - which of course doesn't work.
It has the L79 327/350 and i plan to do some work on the top end to get it up to around 420, however that won't be until the driving/show season is about over. The problem is that I live in South Georgia and its HOT. I would really like to have some AC blowing, but i don't want to pay alot of money to then turn around and have to let all the R-12 out when i redo the motor.
I was wondering if it is "safe" to use something like AC Pro just to hold the system over until i dress the engine. I know AC pro is R-134A and it can cause some seal leakage, but the question is will that permanently damage the seals? Or will it just cause the AC Pro to not be as effective?
If it just ends up being moderately less effective, but overall not damaging it would bring some much needed relief. If it does cause damage I might just have to suffer because I don't want to have to rebuild the system, although that is a possibility regardless.
If anyone has some wisdom they would like to share i'm all ears.
Thanks,
Burning Brakes
Joined: Oct 2001
Posts: 926
Likes: 200
From: TX
If you introduce R134a into your R12 system you will totally screw up your system components. Also, at a minimum you are going to need to reseal your compressor if your system has not been working for a long time. Then you will also need to replace the receiver/dryer. Wait until you have done your engine mods.
VS
VS
Le Mans Master
Joined: Jan 2001
Posts: 6,743
Likes: 1,385
I have converted several R-12 systems to R-134a. Every one of them worked just fine. You can go to a air conditioning website for vehicles and ask there.
From what you are describing I suggest that you would be better off finding some R-12 until you make a decision of which route you wish to take. You want to avoid mixing the coolants so if you just want to have a "some" cooling, then I would try it with R-12.
Later, when you decide to really fix the a/c you'll have the more difficult decision of either fixing the stock system or buying an aftermarket system.
From what you are describing I suggest that you would be better off finding some R-12 until you make a decision of which route you wish to take. You want to avoid mixing the coolants so if you just want to have a "some" cooling, then I would try it with R-12.
Later, when you decide to really fix the a/c you'll have the more difficult decision of either fixing the stock system or buying an aftermarket system.
Drifting
Joined: Aug 2009
Posts: 1,346
Likes: 160
From: new iberia la
mixing R134 into an R12 system is a bad idea.. [ to clarify, r134 and mineral oil from r12 will not mix.. you will burn your compressor] add R12 if you can find some and see if it will cool, probably not. or wait and convert it to R134.. its not difficult. All seals need converting and new Dryer, etc along with thorough system flush .. rebuild or replace compressor .. you can also upgrade your blower to a C4 wheel for 30% more airflow ... Nothing worse than a C3 in traffic in high humid heat
Last edited by fishslayer143; May 21, 2019 at 07:49 AM. Reason: spiled my coffee
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
it is gonna need seals anyway. they are 50 years old. i betcha there is no R12 left in there. the 134 may stay in 1 day. may stay in 2 weeks. it is not a daily driver. i have been adding 134 to partially charged and fully discharged 12 systems since they made R-12 available by prescription only. does the system show any pressure at all? does compressor come on? if you hot-wire compressor, do you get any cold? only run it hot wired for a few seconds.
Le Mans Master
Joined: Mar 2004
Posts: 7,502
Likes: 1,510
From: Little Rock AR
The A/C needs new O-rings at a minimum so why not just fix it first? Use the 134a compatible seals and you can still use them with R12.
No real need to empty the system later. Just disconnect the bolts, set the pieces to the side and pull the engine.
No real need to empty the system later. Just disconnect the bolts, set the pieces to the side and pull the engine.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
At the very least, before you introduce any 'Freon' into the system, have someone with a vacuum pump try to pull a vacuum on the system.
It may save you a bunch of money and some aggravation if there is a leak (really, is there any doubt) and all your 'Freon' just goes up in the clouds. If it does hold a vacuum it may be worth introducing some refrigerant into the system.
Good luck... GUSTO
It may save you a bunch of money and some aggravation if there is a leak (really, is there any doubt) and all your 'Freon' just goes up in the clouds. If it does hold a vacuum it may be worth introducing some refrigerant into the system.
Good luck... GUSTO
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
R12 and 134A have NO compatibility issues. The problem lies in that PAG used in 134A systems is not compatible with mineral oil used in R12 systems.
so to answer your question yes you can put 134A in anR12 system with no ill effects.
If you try to run only 134A with only mineral oil in the system it will not work for long. 134A will not carry mineral oil, therefore the compressor would soon seize.
this is where ester oil comes in. Ester oil is compatible with both Freon types and can be carried by both types and is compatible with both mineral and PAG oil. However no PAG should ever be mixed with mineral oil, whether ester is present or not.
in a 134A conversion where the system is not completely flushed of mineral oil ester oil is therefore used. In this type of conversion R12 and 134A Freon could be mixed with no compatibility problems.
this is all irrespective of the pressures in the system. System pressures will rise as 134 is added. Only talking about compatibility issues.
so to answer your question yes you can put 134A in anR12 system with no ill effects.
If you try to run only 134A with only mineral oil in the system it will not work for long. 134A will not carry mineral oil, therefore the compressor would soon seize.
this is where ester oil comes in. Ester oil is compatible with both Freon types and can be carried by both types and is compatible with both mineral and PAG oil. However no PAG should ever be mixed with mineral oil, whether ester is present or not.
in a 134A conversion where the system is not completely flushed of mineral oil ester oil is therefore used. In this type of conversion R12 and 134A Freon could be mixed with no compatibility problems.
this is all irrespective of the pressures in the system. System pressures will rise as 134 is added. Only talking about compatibility issues.
Last edited by REELAV8R; May 20, 2019 at 02:25 PM.
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Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
No it will not. If the system still has pressure and you try to vent it some oil will escape unless you vent it verrrry slowly. otherwise oil will stay in the system.