Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

R12 to R134a A/C conversion


CMil's Avatar
Member

Join Date: Apr 2002
Posts: 432
MO

04-01-04, 03:33 PM   #1  
R12 to R134a A/C conversion

I hope this is the right place for this post and that I'm not beating a dead horse... I have a 1990 Plymouth Grand Voyager with 3.3 v-6 and dual evaporators (front and rear). I would like to know what's involved in converting this vehicle from R12 to R134a. I've done some research and found everything from " It's so simple your child could and SHOULD do it" to "It's nigh impossible, way expensive, totally unsafe and very ineffective". This forum has always steered me straight in the past, so I find myself once again asking for advice/input.
So, can it be done and made effective? If so, what all should be replaced for best results? What would constitute a full oil charge and how much refrigerant should I expect to use for this vehicle? My A/C experience is limited, but if I know what needs to be done, I can do it. Any help is greatly appreciated. Thanks in advance - Chris

 
Sponsored Links
Warn's Avatar
Member

Join Date: Mar 2004
Posts: 37

04-01-04, 04:29 PM   #2  
Its both simple and not so simple. If you start taking components apart you have to replace them with different ones. ie. Take a seal off and now has to be a r134 seal. If you dont do anything else its very easy. Change a few fittings, add some oil and start vacuuming the system.

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-01-04, 04:54 PM   #3  
Let me start out by saying I don't recommend doing this. Systems that were engineered for R12 traditionally do not perform well with R134. In some cases, it works but most of the time the condenser is too small, the fan is insufficient and an already tired compressor usually quits under the extra load. Some of the other problems is that when R134 is introduced to mineral oil (R12 oil) it turns to jello. This can happen in a place where not much is effected or it can cause a real problem. R134 is also made of smaller particles and can find a smaller leak.
Having said all that, here's your concerns and procedures. First you have to remove as much of the old oils as possible. That usually means removing compressors and flushing condensers and other components. An additional condenser fan will improve things. You need to charge the system with preferably "ester" oil which is compatable with both R12 and R134. Charge the system with 80% of the original capacity of refrigerant and hope for the best.
The proper way to do it is to repair the leak and charge the system with the R12 an it will work much better than converting it.

 
mike from nj's Avatar
Visiting Guest

Posts: n/a

04-01-04, 09:58 PM   #4  
mike from nj
to add to that,

certain vehicles can't be converted and yield any good results, for example, early 90's dodge full-size vans. the compressor's capacity is maxed out for a dual system. trying to ask more from it (by adding 134)results in a big disappointment.

and if you don't already have 'barrier' style hoses (started in 92-93ish), the smaller molecule r134 will easily find it's way out of the system(which you already have a leak in).


some systems want you to custom wire a high pressure cut out switch to save the compressor when pressures inside climb too high.


there's a lot more than just adding different freon, and i don't even know all the answers of what needs to be done


maybe talk to an a/c and radiator shop and see what they recommend and how long they will stand behind their conversions.

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-02-04, 02:33 AM   #5  
Originally posted by mike from nj

maybe talk to an a/c and radiator shop and see what they recommend and how long they will stand behind their conversions.
I worked at an A/C shop and they won't even do it. Being in South Florida, I see an awful lot of this.

 
davo's Avatar
Member

Join Date: Apr 2002
Posts: 2,417

04-02-04, 04:34 AM   #6  
I don't convert them over because I have seen shops get sued(losing)over conversions that didn't work well.Do the whole system or keep it r-12.If it gets real hot in NM it won't cool enough on 134 because you lose at least 8 degrees at the vent,I know it doesn't sound like much but it is.

 
Warn's Avatar
Member

Join Date: Mar 2004
Posts: 37

04-02-04, 05:32 AM   #7  
and charge the system with the R12 an it will work much better than converting it.
You guys still get it down there?
It is impossible up here. For one its the law and two its non existant. You cant find it anywhere even if you tried.

 
car nut's Avatar
Member

Join Date: Aug 2003
Posts: 478

04-02-04, 03:40 PM   #8  
R-12 is plentiful on E-bay.

I have plenty in Kansas City, come on over.

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-02-04, 03:50 PM   #9  
Originally posted by Warn

You guys still get it down there?
It is impossible up here. For one its the law and two its non existant. You cant find it anywhere even if you tried.
NO
It's readily available EVERYWHERE, just not to the DIYers. Believe me, it is NOT the law to retrofit an R12 system. I can buy it from multiple suppliers in 12oz cans or 30lb bottles. It can only be sold to shops that own a recovery machine.

 
Warn's Avatar
Member

Join Date: Mar 2004
Posts: 37

04-02-04, 03:53 PM   #10  
Hmmmm.....Maybe thats why we do so many conversion kits up here

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-02-04, 04:08 PM   #11  
Originally posted by Warn
Hmmmm.....Maybe thats why we do so many conversion kits up here
I just realized you were out of the country. I don't think that changes too much though. You can get product from the US easily. I don't really think anybody in Canada does enough A/C work or have hot enough temps to even realize the problems from retrofitting. Our cars run in 95 plus degrees for months at a time. It's pretty easy to notice a 5 degree loss.

 
mgeubtn's Avatar
Visiting Guest

Posts: n/a

04-03-04, 07:40 AM   #12  
mgeubtn
So that'ts why

Now I know why the AC conversion Pepboys did on my 91 Dodge Dakota never worked. The hoses weren't up to spec. All of dye they shot in that system should of showed that the new refrigerant was leaking somewhere, but it never did. They replaced almost every other part except the hoses.

I ended up selling the vehicle.

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-03-04, 02:37 PM   #13  
Without going into specifics, pick another shop to do A/C repairs next time. Most of their locations have a couple of good techs but most aren't.

 
Pendragon's Avatar
Member

Join Date: Jul 2002
Posts: 1,835
FL

04-03-04, 04:31 PM   #14  
It can be done, it's pretty easy (you will need a vacuum machine), and although it's recommended you change the dryer, you don't HAVE to.

That being said, if your current system isn't up to par for any reason, it's not going to work any better on 134.

And it will work on 90's full size dodge vans with dual air. Mine was converted (before I bought it) and worked great, even here in florida.

I've converted at least 3 cars to 134 and they've all worked fine.

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-03-04, 04:41 PM   #15  
Originally posted by Pendragon
And it will work on 90's full size dodge vans with dual air. Mine was converted (before I bought it) and worked great, even here in florida.

I've converted at least 3 cars to 134 and they've all worked fine.
You need quite a bit more experience before you tell these dealer techs they're wrong. There are MANY problems with retrofits and if you had a clue what your talking about, you wouldn't contradict people that have worked on thousands of these situations. Just because is hasn't "blown up" yet doesn't mean it's working right.

 
CMil's Avatar
Member

Join Date: Apr 2002
Posts: 432
MO

04-03-04, 05:54 PM   #16  
Wow! What a can of worms it looks like I opened up here! Okay, I've seen this happen on this forum before. So before it gets to the point of name-calling, hurt feelings and people quitting the forum (if you've been with the forum a while, you've seen it, too), let me see if I understand what's been offered.
It seems I can change anything, from just adding service port adapters to replacing every component of the system, and get results varying from worse performance than an empty R12 system to new-car-like cooling. It appears to boil down to how much I'm willing to spend, how much work I'm willing to do (or re-do), and how important the cool air is to me (or my wife!). Everyone has given valuable input, and I appreciate it all. I think I will look into repairing leaks in the existing system and recharging with R12. If that doesn't work out, I will start near the middle, replacing compressor, drier/filter and expansion valves, along with all associated o-rings. If problems/leaks crop up, I will proceed with changing the remainder of the system.
Again, Thanks to all for the valuable information. I will use it prudently. And let's all do our part to keep this forum a place for the FRIENDLY exchange of information and ideas. - Chris

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-03-04, 06:00 PM   #17  
Originally posted by CMil
I think I will look into repairing leaks in the existing system and recharging with R12. If that doesn't work out, I will start near the middle, replacing compressor, drier/filter and expansion valves, along with all associated o-rings. If problems/leaks crop up, I will proceed with changing the remainder of the system.
Again, Thanks to all for the valuable information. I will use it prudently. And let's all do our part to keep this forum a place for the FRIENDLY exchange of information and ideas. - Chris
Repairing and using R12 is the best way to go. Don't just start throwing parts at it. You can get a complete leak check and diagnosis for under $50. Just make sure it is a reputable A/C shop so you can rely on the results and make a decision from there..

 
pmgheritage's Avatar
Member

Join Date: Dec 2003
Posts: 312

04-04-04, 10:06 AM   #18  
Originally posted by Desi501


You need quite a bit more experience before you tell these dealer techs they're wrong. There are MANY problems with retrofits and if you had a clue what your talking about, you wouldn't contradict people that have worked on thousands of these situations. Just because is hasn't "blown up" yet doesn't mean it's working right.
You sure do get irate at times when someone disagrees! I have done countless retrofits since the mid-90's, on every kind of vehicle on the road, with very few performance problems. Granted, I don't live in the sunbelt, but it does get pretty toasty around here in the summer. When done properly, a retrofit will show an avg. of 4 degrees or less temp. difference at the outlet. The key word is 'properly'. We learned by trial and error for the most part, given the hundreds of different "recommended procedures" that were put out when 134a first appeared. In a nutshell, there are 6 basic steps:

1.) COMPLETE recovery of any remaining R12.
2.) Open all serviceable connections (i.e. condensor, compressor, evaporator, etc.), after purchasing a 134a conversion and re-seal kit. These are readily available, both generic and vehicle-specific.
3.) Remove for replacement reciever/drier or accumulator and expansion valve/orifice tube. Both of these components should be replaced, for optimium performance and to properly flush the system. Inspection of the valve/tube will also give you a pretty good idea of the compressor condition.
4.) COMPLETE flush with an approved product. Wynn's distributes an excellent one. It's economical, very efficient, and easy to use. The key is to make sure ALL of the old oil is removed.
5.) Install new 134a compatible oil; O.E. specific is best. I normally inject 1/3 of it in the drier before installation, 1/3 in the compressor, and 1/3 in the condensor. Install the new service ports (after removing shrader valves from the R12 ports), and close all connections with new 134a seals.
6.) Evacuate and recharge to 80% of R12 charge. Obviously, there are many variables involved, but 99% of the time the pressure difference will be so minimal as to be unnoticeable, as will the outlet temp.

It can be done, and it can be done effectively, in both performance and cost aspects. Especially given the cost of R12 in some markets. The only consistent problem I recall over the years is with Jeeps, and the 'barrier' style hoses mentioned above. It's almost a moot point anymore though. Given the age of R12 equipped cars, this operation will be irrelevent in a few years. Also, given the equipment and special tools required in many cases, it's not a job I'd recommend for a DIY'er. I haven't done "thousands" of retrofits, but they do number in the hundreds, and the problems encountered were FEW.

 
Desi501's Avatar
Member

Join Date: Oct 2003
Posts: 2,207

04-04-04, 02:59 PM   #19  
Although your instructions and methods are correct, it's the engineering of different models that causes the problems. The engineering requirement are different for R12 and R134. Things like condenser capacity and air flow specs are different for R12 and R134. putting R134 into a system that was engineered for R134 is rolling the dice. One car will work great and the next will work like crap. If your in a climate that never really tests the limits of the system, you'll never really know what they are. In a low ambient condition a system that isn't even full will seem like it's doing well. Now put that system to a real test and park it out in the sun in 95' temp for 5 hours and see how long it takes to pull that inside air back down. Your duct temp will climp 15' in some cases and a marginal compressor will not hold up well in those conditions and probably leak a whol;e lot faster with the extreme pressures that temp and load will bring. The bottom line is, if your not really testing the system's limits, it really doesn't matter what your doing to it. It will seem OK. I know many A/C specific techs and not one will recommend retrofits.

For the record, it wasn't me you contradicted about the Dodge van but it was a guy that knows Chryslers inside out and he wasn't wrong. We might as well put this to rest because the poster has learned what he needed to.

 
davo's Avatar
Member

Join Date: Apr 2002
Posts: 2,417

04-04-04, 04:58 PM   #20  
CMil seems satisfied and so I'm closing this thread.Davo.

 
Search this Thread