Looking for more A/C info for 134 changeover

dbd

Registered User
1990 SC – Stock –
A/C seized, was working in morning – afternoon oops.
Did a search and found some information, but haven’t found answers about using parts for the 94 on the 90.
I am going to change all of the components and go with 134a, but have a couple questions.
Looking for input from people who have changed to 134a and have info on things that does or doesn’t work.
Probably the biggest question is about a condenser and hoses.

I see that the 94 came with 134a. Everything I install will be new. (no rebuilds)
I have checked parts and found that some of the stuff is the same between the two years.

Should I use the parts from 94 that are different? These include the following parts.
Accumulator
Evaporator core (may not fit due to the years)
Condenser (94 uses a fan – may or may not be a problem)
Pressure switch
Discharge/Suction hose combination – Have found the combo set for the 90 but not for the 94.
They both use the same part # for the liquid line with orifice. So I don’t see why I can’t use the discharge/suction combo for the 90. Still researching this.

Parts I found the same between the 90 & 94
Compressor, Inline filters, O-ring and gasket kit, Liquid line with orifice

I realize the change in test hose connectors and will do what is needed with the correct adaptors.
But can I use the same gauge set that I have used for the R12 – Not familiar with the pressure settings for 134a yet. Don’t think there is anything special about the gauges as long as the range on the dial is high enough.

Hopefully I will be able to get close to the quality of cooling in my Mark & F150 if I change enough parts.

Thanks in advance for any input
dbd
 
I have not actually done the swap as you have described but have some information for you.

The hose running from the condensor to the Accumulator Dryer is a different diameter than the early models (larger) so you have to swap the Accumulator Dryer at the very least. The pressure switch in that line is a over pressure shutdown. Unless you are willing to wire it into the AC Compressor clutch circuit it will be non-functional. The "other" line from the 94-95 has the correct orifice in it to be run with R134A. With that said I am running R134a with original orifice line with no significant issues other than slightly less cooling. I am not sure about the condensor fitting or being able to make the line connections since I am running an AirCon shortened condensor.

When you buy a new compressor likely it will be R12/R134A compatible already (at least the Visteon Unit I got was so I could have swung either way had that been my choice).

Perhaps someone else can add some details too.
 
OH....the connections to R134A for your gages is different. R134A runs at a higher pressure. You will need to use the correct O Rings in the system for the type of oil you end up using.

Spin the compressor by hand after installing it and the lines and evactuating the air, to partially circulate the oil. Bad idea to spin the compressor with the engine when topped off with oil.
 
Duffy
Thanks for your input - everything helps.
I will look into the pressure switch stuff - Re-wiring isn't a problem as long as I gain from it. The 134 doesn't care about having enough pressure for turn on?
Here is what I found on the condenser since I posted last.
Looks like I can use either the 90 or the 94.
The 90 is a bit larger. The pictures of both units look identical - so indexing for the lines would not be an issue.

dbd
 

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The cycling (and low pressure cut-off) is controlled by the pressure switch in the Accumulator Dryer. Some if not most are adjustable but if you go with a the 94-95 version it will already be set-up (pressure wise) for the R134A. The "other" pressure switch is over pressure protection that will cut-off the compressor if system pressure is too high instead of blowing the relief, a portion of your freon charge and oil out to the atmosphere and making a mess in the engine bay.

Wasn't referring to indexing the lines but rather if the actual connections for the hose can be used on a different version condensor (size/diameter issue). Looking at the info you provided they seem to be the same size connections. Personally I would go with the larger condensor.
 
Back in 1993-94 when they first introduced the R-134, Ford came out with kits for us Dealer Technicians to install. They consisted of everything but the evaporator. A few years later they realized that it was not necessary. My car is retrofitted to R-134 as are several of my previous vehicles. All I did was screw the R-134 fittings into the R-12 fittings and added freon until the compressor quits cycling and check my pressure. The r-12 and R-134 run at around the same pressures(R-134 is slightly higher), 25-35psi (Low side) and 250-350psi (High side). What they were really worried about back then was the oil compatability. Do not put in the recommended amount of R-12. It will take less R-134 to operate the system in most cases. My point here is that you do not need to do a complete retro-fit. However if you are replacing the system anyway, you may as well use the 1994 components. Other than a Low side cycling switch connector(Two wires), I really dont see what you would have to rewire though. There are only three other electrical components, the Clutch (Same connector), the High pressure Switch (Same connector) and the WOT relay (Same).
 
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Does any one have a parts page picture of the 94 air conditioning. Looking for the picture that will show the hoses.

Thanks
dbd
 
You need a modern, that is 94 and up, condenser, and about 32 oz of r134 to make it work well. Also, adjust the pressure switch to drop out at around 20 psi. The normal r12 switch (89-92) years is set to about 26 psi. Won't hurt to use it, but you won't get the most effective cooling either.

Unless you're got a lot of experience with MVAC systems, to do the best job of charging it, you need a pressure guage set.
 
Yea I am getting there - I will post all the part numbers after I have completed and checked it out.
So far here is what I will be using. All parts will be new(no rebuilts)
Stock compressor
94 condenser
Manifold hose setup for the 90
Accumulator for the 90 (checked with manufacture and the one I want has the correct desiccant for 134a. Needs to be XH-7/XH-9. Using the 90 accumulator keeps me away from the hose size change on 94.)
Pressure switch for the 90. (found one with correct thread and set for the 134a).

Not sure about the the high pressure cut out switch yet. You would think the R12 system would have a high pressure switch, but I could not find anything in the 90 EVTM. Am I missing something here in the way I am looking at the switches.
Not sure where the high pressure switch is located so some of my planning may change.
I do have my own gauge setup for both. 1-r12 & 1-134

Thanks
dbd
 
Back in 1993-94 when they first introduced the R-134, Ford came out with kits for us Dealer Technicians to install. They consisted of everything but the evaporator. A few years later they realized that it was not necessary. My car is retrofitted to R-134 as are several of my previous vehicles. All I did was screw the R-134 fittings into the R-12 fittings and added freon until the compressor quits cycling and check my pressure. The r-12 and R-134 run at around the same pressures(R-134 is slightly higher), 25-35psi (Low side) and 250-350psi (High side). What they were really worried about back then was the oil compatability. Do not put in the recommended amount of R-12. It will take less R-134 to operate the system in most cases. My point here is that you do not need to do a complete retro-fit...

DITTO

Same thing at the Acura dealer I worked for, at first everything had to be swapped then they backed off even replacing the o-rings after a couple of years doing retrofits.
It was taught later that PAG oil used in R134 systems does NOT damage normal rubber o-rings used in an R12 system like we were first told.

Just replace the bad parts, vac it and charge it. Pretty simple and always had success and even some improvement at times on R134 conversions.
 
Finally someone comes up with the right answer.
The only thing you need to change is your siezed compressor,install retrofit fittings and evac/recharge the system.
Changing your dryer is not a must but because the compressor siezed you may have debri in there.
With 134 it will only be 80% of your original charge as it runs at higher pressure.
I converted my 91 with a low side retro fit fitting(free as i had one lying around),evaced/recharged the system and it blows ice cubes all summer long.
I also did my o-rings but only because they where 15yrs old and were leaking a bit.
Don't let all these guys tell you different,do it the easy way and save your money,i've done several older ford's this way and they all work great to this day.
 
Don't let all these guys tell you different,do it the easy way and save your money,i've done several older ford's this way and they all work great to this day.
Except when they don't. :rolleyes: Your advice is all well and fine for when you live in a mild climate. However, if you live in heat (like Texas) and you want a system to last more than a year, you should do it the right way. If you have the time for re-dos, you can patch things one at a time.

This much is for sure, the condenser for an R12 system won't do the job in heat. If you want it to cool you on a 102+ degree day, you need a better condenser.

Its your time, your $.. spend them as you wish. ;)
 
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Finally someone comes up with the right answer.
The only thing you need to change is your siezed compressor,install retrofit fittings and evac/recharge the system.
Changing your dryer is not a must but because the compressor siezed you may have debri in there.
With 134 it will only be 80% of your original charge as it runs at higher pressure.
I converted my 91 with a low side retro fit fitting(free as i had one lying around),evaced/recharged the system and it blows ice cubes all summer long.
I also did my o-rings but only because they where 15yrs old and were leaking a bit.
Don't let all these guys tell you different,do it the easy way and save your money,i've done several older ford's this way and they all work great to this day.

Humm... looks like all I might need to do to the 5.0 is new o-rings and evac/recharge.
 
94 condenser difference in fit

OK.. After taking my shoe-horn :rolleyes: to it, I was able to squeeze the 94 condenser into the space that the original 90 condenser occupied.

Due to the posts on the 94 model being further apart, I moved the lower rubber mounts closer to the radiator support and knocked the frame tabs down flush. Since the newer model is also about 3/4" taller, I had to leave the upper rubber mounts off entirely; they wouldn't fit. However, there is a 1.5" wide rubber flap in the original space along the top side that I used to slip over the back of the condenser that holds the newer model in place securely.

The condenser's oulet tube which is resting against the frame just a bit so I plan to use some rubber scrap to pad that just in case. The original hoses mate up just fine.

I plan to finish up the orings and pull a vacuum this evening so I don't have to sacrifice a new drier just to find out if anything leaks. If it holds vacuum for 24 hours, I'll install a new drier and charge it up.

I'm using a blue otube this time just to be sure of what I've got and hopefully to pull the top end pressure down a bit. :)
 
Leak finding tips

OK.. so after all the work, my setup failed to hold a vacuum. :(

I used all new Orings and nylog ring lubricant. Fortunately I didn't waste a new drier to find out.

Any tips on how to find the leak(s)? I have dye but I don't have a cylinder of nitrogen to use. I don't care about moisture at this point since I'm just trying to find the leak so if plain old humid air will work I'll give it a shot.
 
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