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Auto/Truck/Other Transportation If you use it to get from here to there, this is the place to talk about it and how to fix it.

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Old 05-25-2012, 08:51 PM
OzarkCountryboy OzarkCountryboy is offline
Join Date: Apr 2011
Location: Central Missouri
Posts: 106
Default Converting from R-12 to R-134A

Curious as to if anybody on here has converted their vehicle from R-12 to R-134A themselves. 2 of my vehicles have low enough pressure in the A/C systems that the compressors do not kick in due to low pressure switch. Don't really want to spend the big bucks that mechanics want to have them converted and thought about trying it myself. The wood truck can do without as it doesn't get driven much but the daily driver would be a little more comfortable with A/C while waiting in traffic. Here are the 2 vehicles does anyone have any experience changing their A/C or are there any particular issue with changing over these fords? Thanks for any input or advice.
1. 1986 Ford F-250 Ext Cab 4x4 4spd. 6.9idi Diesel
2 1988 Ford Bronco II 4x4 V-6 5spd.
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Old 05-25-2012, 11:42 PM
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Tim Horton Male Tim Horton is offline
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Join Date: Sep 2002
Location: In the bush of BC Canada
Posts: 6,107

I've been told it can be done. There are kits for most vehicles, I guess.

New connections that mount to and lock onto the existing R12 connections. Lube, refrigerant etc.

I think one of the biggest things is licensing people to recover the old R12, because it is such a hazard to the environment.

If you have a vac pump and can handle the materials, I think the tec info should be available for your specific systems.

Good luck
Always fresh.
Keep your stick on the ice. Red Green
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Old 05-25-2012, 11:51 PM
OzarkCountryboy OzarkCountryboy is offline
Join Date: Apr 2011
Location: Central Missouri
Posts: 106

Wyo, the kits I've seen are pretty much universal and surprisingly now days they are cheap since all the newer cars already take 134 and there's not that many on the road anymore that don't take it. I guess that's what hangs me up is the recovery part as these kits are advertised in a way that leads one to believe anybody can do it with only what's included in the kit but I'm thinking the system needs to be drained and flushed and then a vacuum put on it before charging it again? Just trying to get around having to drop a couple hundred to the mechanic but may end up doing it anyhow.
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Old 06-03-2012, 07:10 PM
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gregabob Male gregabob is offline
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Join Date: Oct 2008
Location: Upland CA
Posts: 418

I've done this to my car (85 VW Jetta) and truck (89 Dodge Dakota). I have access to an R134A machine at work. The kit was simple to install, just fittings on the existing fill ports. You can flush the systems too if you want--there's solvent available in 1 qt. cans. I don't get too wound up about the supposed 'ozone depleting' factor--R12 is 7 times heavier than air. It doesn't 'float'.
You may be able to rent a vacuum pump to get all the air and moisture out of your system before recharging. You can then recharge with the can adapter and hose you buy with the kit. R134A can be obtained in 1 lb. cans. You generally use less 134 than 12. 134 takes a different oil too. It also depends on the type of compressor you have. Do a little research and the job will be relatively easy.
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Old 06-04-2012, 06:14 PM
johnny Male johnny is offline
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Join Date: Nov 2008
Location: Ft Worth, Tex
Posts: 2,007

Get you a can or two of 134 and the hose and
adapters and 'top off' with 134.
They ARE compatable!
One can in each vehicle is probably all you need.

Do not get suckered in to the change out and flush
train of thought unless you just have extra money
to toss to a mechanic.
They will accept it tho if offered!

IF you know an a/c person well--ask them.
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Old 06-04-2012, 10:32 PM
Ohio4us Male Ohio4us is offline
Join Date: Aug 2010
Location: nw ohio
Posts: 48

I hate to tell you but r12 and r134a are not compatible. Wouldn't risk the hazards by mixing them. Don't let anyone know if you release it into the air because its a 10,000 fine if the epa finds out. they do make one that is compatible with both its called hotshot (r414b). If you get rid of the Freon that is in it should be able to change it over just vacuum it down and put in new Freon. If it gives you any fits try changing the pressure switch on it to one that is compatible with the r134a. I've been doing Ac's (home and auto's) for several years now.
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Old 06-05-2012, 02:18 PM
grumble Male grumble is offline
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Location: W NM, a rifle shot from the Great Divide
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Pardon the dumb question, but what happens if R12 and R134a are mixed? I realize condensation pressures might be changed and be less efficient than either by itself, but is there any harm?

I've never seen it done, and am curious about what would happen.

On a side note, did y'all notice that as soon as the law about freon was passed and signed, the ozone hole so-called "problem" went away? Nothing changed, the "holes" are still there (as they always have been), but a feel-good law took the subject off the radar.
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Old 06-05-2012, 11:26 PM
Ohio4us Male Ohio4us is offline
Join Date: Aug 2010
Location: nw ohio
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Know someone that actually mixed the too and besides the pressure difference. It ended up messing up compressor on his car by having different pressures it made the refrigerant unstable.He had bought the car right before they switched to r134 and that is what was determined that caused the compressor to fail. Yea I did notice the problem went away for awhile now its starting to come back and they are trying a bunch of new regulations on freon. With the prices keep raising going to be a lot of people cant afford all the freon prices. There is a new freon coming to replace the r134a it is r1234yf and it will require all new equipment to check because there is just enough difference in pressure that all the r134a equipment wont be accurate enought to beable to check it.the freon right now is almost 3 times as high in price as the r134
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Old 05-08-2013, 04:16 PM
HuskerHomesteader Male HuskerHomesteader is offline
Join Date: Feb 2013
Location: Enslaved in Omaha
Posts: 25
Default Refrigerant Oils not compatable.

It is not so much that the two refrigerants are incompatible, but that the lubricating oils that are used with each are not. R12 uses ester oil and R134a uses Pag oil. When these two oils mix they wind resulting in something that looks like mayonnaise. I have been in the automotive industry for ten plus years now as both a technician and manager and have converted several vehicles from R12 to R134a. There are only three parts that absolutely have to be changed: the low pressure fill port, the high pressure fill port and the receiver/drier.
The low and high ports have to be changed as the equipment for R12 and R134a are different sizes (for good reason). The receiver/drier has to be changed as it is basically a can with a desiccant in it. The desiccant absorbs any residual moisture in the system to keep it from fouling the compressor. It is also pretty good and holding a certain amount of oil in it.
My only other suggestion would be to remove the compressor from the vehicle and fill it with mineral spirits, spin it half a dozen times and then let it sit and dry for 24 hours before reinstalling. Pour some pag oil into the compressor before installation.
There will be some residual oil in the lines, but there isn't much you can do about it, it will wind up gelling with the PAG oil, but it most likely will be trapped in the receiver/drier and not harm the compressor. Hope this helps!
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Old 05-08-2013, 06:40 PM
J R Adams J R Adams is offline
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Join Date: Jan 2011
Posts: 1,553

I still have 3 cans of R-12 if anyone is interested.

Heard on the news once that someone had used propane in place of R-12. A/C worked fairly well and wasn't discovered until the car eas taken in for A/C service. Checked th gas tables in the ME hand book and the gas properties are very close in pressures and temperatures.
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Old 10-28-2013, 01:19 AM
ironmonger Male ironmonger is offline
Join Date: Aug 2013
Location: Waukesha,WI
Posts: 18
Default R12 sub

Instead of converting the system to 134a, why not use propane instead. Propane is an excellent refrigerant, and the propane is compatible with the ester lube oil found in your R12 system.
One common knock is the fact that propane is flammable... and the 120 pounds of gasoline in your fuel tank isn't?
I don't believe that there are many catastrophic system failures that would result in the rapid release of all the propane at once, and the dumping of 2 pounds of propane is much less dangerous than R12 that is released into a fire. No one likes phosgene gas...I'd rather have the propane burning...

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