A/C system upgrade for MTX parts AND procedure

[93rev2sev]

Use these directions at your own risk. I admit no liability whatsoever - this is simply a recounting of the procdure I used.

At the beginning of the summer, I upgraded my A/C. I waited till now to post the procedure to make sure it kept working. I'm not an A/C guy but I did a little research and it still blows cold so here goes...it's not that hard - just very time consuming.

Retrofit parts to convert to 134a:
Napa Rocks for A/C hoses...all parts pictured online.

$35 retrofit kit and 2 extra oil charge cans(they are small).

New, clean Mineral oil. This will be used to **** the new o-rings just like you would **** the seal on an engine oil filter.

accumulator(large diameter hose with big canister): napa part number TEM200680

Liquid line: (small diameter flexible hose - cause of "ford black death" if not replaced - google it - it's a real term) napa part number TEM200955

Discharge/suction line: (mates the other two hoses and hooks to compressor - has compressor manifold) napa part number TEM282810.

Compressor: must be compatible with 134a - any remanufacured 134a gen2SHO compressor will work - I stolt mine from a 95 automajic. Napa gets $385 + a $60 core so I wont list the part number.

All these new hoses will have new o-rings...keep them safe or buy some extras - better yet...both. ebay is good for these. Search 134a o-ring

Procedure: dig in....get stuff out of the way.

Battery/tray

Alternator

Lower motor shock/bracket- attached to the front motor mount - I have reinforced motor mount so I discarded the shock/bracket - it's a noise/vibration/harshness thing. With the reinforced mount...it's rendered useless. Remove this for the A/C work as it's totally in the flippin way!

Upper motor shock and bracket - mine broke while removing - a better idea is to remove intake plenum crossover tube where the DIS ignition module is attached.

Power steering reservoir - don't disconnect hoses just move it out of the way. I shoestrung mine to the intake tubes.

Rear engine bay sight shield(vanity panel).

Coolant overflow bottle

That should provide you with enough room to get at all the A/C guts.

Procedure:
discharge the A/C system...If you are environmentally friendly, goto a service station and have them recover it. Other wise, empty it like a tire...dont touch the stream of freon - you wont like frostbite.

Start disconnecting stuff...I started at the firewall...This is where you say for the first time....not that hard?! that guys nuts. The little white plastic disconnect tools WILL work...use the right size and wiggle the shit out of the hose...because it's old it might be "frozen" together with a/c system sealant.

Once you have the hang of the disconnect tools...the rest of the disconnections will be just as hard...lol but its true.

Disconnect both fittings at firewall
Disconnect both fittings at front of engine bay...small one on top...larger one from underneath.
Disconnect the electrical fitting on the top of the big canister (this should be replaced too...it's the low pressure cut off for the compressor. 134a systems run at a different pressure - I reused mine...it's really a safety cut off so the compressor won't run while the system is empty.
Unbolt the A/C compressor manifold and remove all three hoses. The large diameter accumulator hose will be a little tough to thread out but with the right stuff out of the way..it is possible.

Unbolt the compressor and set aside.

Now all the old hoses and compressor are out and the only things that remain are the condenser and evaporator - everything else gets replaced.

Bolt up the new compressor but don't remove the shipping plugs if there are any...if using a salvage compressor, make sure to cover the holes with masking tape immediately upon removal from donor car - dont want to get ANY gunk in there. A quick check to see if the donor compressior is any good can be accomplished by seeing of there is any pressure in the donor system. depress the stator valve on the firewall of the donor car...if it hisses, the old donor car had at least SOME charge...indicating that there will be little if any contaminants in the compressor.

Carefully install the new o-rings on the new compressor manifold - scratched o-rings amount to leaks. **** the installed o-rings with a (clean)finger covered in mineral oil - just enough to moisten them. remove plugs or tape from compressor (clean surface of salvage compressors with alcohol or brake cleaner on a shop towel or scotch brite pad- get it good and clean) and bolt manifold to compressor - I made them almost as tight as I could with a 1/4" rachet and wrist torque(no pulling or pushing) - the bottom line is...don't crank so hard you break or strip things - there might be a torque spec...but I found none.

The other hoses should snap together quite easily.

Reassemble accessory train/button everything back up except for the low pressure cut off switch.

Charging the A/C system:
With the car shut off, charge the system with the 2 small cans of A/C oil charge - I think they have 2 ounces of oil each.

Start car and turn on max A/C - your compressor will not start because the cut off switch is disconnected. You have to jumper the switch to start the compressor. I jumpered the compressor 5 times for 5 seconds each - wild guess. I did this in order to circulate the oil - I don't even know if it's right but it felt like a good idea at the time - I doubt theres a guy on the assembly line at Ford that does this.

Plug in your low pressure cut off switch.
Charge the system with 1.5 large (15 ounce) cans of 134a retrofit charge - these also contain oil and system sealant and conditioner. Your compressor should automatically come on once there is sufficient charge. If not, disconnect the cut off switch and jumper it while you charge the system. The compressor must be on during charging. I think the capacity is between 25 and 30 ounces, but it should be on your emissions tag attached to the radiator plastic information thingy - I'm told by an A/C guy that you can't over charge with these small canisters but if the system calls for 30 ounces of r12 - use 25 ounces of 134a or until your vents blow cold enough.

I'm sure there are others that have slightly different procedures in mind but this seems to be working for me. I hope it helps you. It's been several months since I performed this procedure so I might have forgot the carrots but the meat and potatoes are all there. This is WAY more direction than I had so I'm sure you can do it if you DECIDE.

 

[projectSHO89]

Do not use mineral oil. It is not compatible. Use PAG or POE oil. Whichever will work, follow the compressor manufacturer's directions. Whatever you use, be consistent, do not mix oil types.

The liquid line does not cause "black death". "Black death" is the debris left over in the system from a compressor internal failure. It usually clogs the condensor and the orifice tube (which is located in the liquid line.)

That switch on the accumulator is the cycling switch, not just low pressure cutout. It is integral to the operation of the CCOT system. It is also adjustable for the low pressure triggering setting.

It is highly desirable to flush the evaporator and condensor cores to remove all the old mineral oil from the system. Laquer thinner makes a good, locally available flush agent. Blow out with clean, dry shop air.

Oil: System oil capacity is 7 oz. To little and you risk premature compressor failure. Too much and you loose efficiency. Add 1 oz to the the clean condensor. Add 1 oz to the clean evaporator. Add 2 oz to the drained and cleaned donor (or new) compressor, turning it by hand to work the oil into the innards. Add the remaining 3 oz of oil to the accumulator can.

VACUUM THE SYSTEM. You have to remove the air and moisture! If you don't, you will have reduced efficiency plus the remaining moisture will saturate the dissicant in the accumulator quickly leading to premature failure due to internal corrosion.

There is no need to jumper the cycling switch when charging into a vacuum. Just hook it up like its supposed to be.

Correct system capacity is approx 26 oz of R134a. (80% of the original R12 charge).

If charging into a vacuum, you can charge as a liquid for the first stage of the process. Warm your cans of R134a in a bucket of hot (110F) water until thoroughly warmed. With the engine off, invert the can and open the valve(s). The first can will charge almost completely into the system by itself.
Turn can right-side up, and start the engine. Turn on MAX AC, blower on HIGH, and set engine RPMs to 1200-1500. Give the system several minutes to pull the last remaining R134a gas from the can. Then change to your second can, keeping it upright while the gas is drawn into the system. Be patient and let it do its job. Do not invert the can. Shake it periodically to see if the liquid has all been transferred. During this process, you will observe the compressor clutch going from a very short on-cycle to progressively longer cycle times. Once fully charged, the clutch will likely stay on full time if the ambient temp is over 80F. Add another 2 oz of R134a if you've been using the 12 oz cans. The 2 oz can of oil charge is a good way to get this if you're not using a large tank and a scale. If you do use the 2 oz can, subtract 2 oz of the oil from the accumulator's initial fill.

Low side pressures should be between 25 and 40 psi and the high side should be between 200 and 350 with the high side pressure HIGHLY dependent on the ambient temperature. The hotter it is, the higher the pressure will be.

Hand-feel the evaporator inlet and outlet lines. When they're both of nearly the same temperature, your charge is very close. Avoid overcharging!

Center vent temps of 40-45 F should be obtainable if everything was done correctly.

Steve

 

[93rev2sev]

hey thanks

well there ya go...
Like I said, I'm not an A/C man...but I did stay at a holiday inn express...

LOL

 

[doclees]

Projectsho89 is it a "must" to change the compressor? Can it not be flushed and saved? When you replace all the parts that shops recommend its about a hose and dash removal from gutting the entire system.

 

[jelloslug]

When I changed mine over to 134a all I changed were the o-rings (because most of them were leaking) and the oil, then I just pumped it down for an hour and charged it up. It has been working fine for about 3 years now.

 

[rangerj]

Note: It is not necessary to change the compressor, BUT DO NOT clean out the compressor. All you have to do to the compressor is drain as much of the R-12 oil as is possible. To do this set the compressor in a container so that it drains and let it drain over night or longer. Then add R-134a compatabl oil, say 3 to 4 ounces into the suction port. All other system components can and should be cleaned, but it is best to replace the accumulator (filter/dryer) and the oriface lines. The condenser should be removed, cleaned, and pressure tested by a shop (pressure test first). As Steve stated the system takes approximately 7 ounces of oil (maximum) and new components should be treated with oil before assembly. The oil becomes a vapor and circulates throughout the system when it is operating. Again, vacuuming the system before adding refrigerant is critical. It removes air and the moisture contained in the air.

 

[zak]

Seems like the best place to post this. After much digging I found the O-ring part numbers for the evaporator line connections pretty sure this covers 1990 to 1995. While there are a few of the first one around at obsolete Ford parts houses, to the right of each I will give the common trade number that an O-ring supplier would use to look up the size.

Ford 389158-S100 6338907
Ford 390209-S100 6339124

I believe one of these is superseded by Motorcaft YF-2960 Ford 1W1Z-19E899-JB, but haven't figured out which one is which yet.

W0133-1811288

 

[zak]

Lots more info on how to clean these garter spring fittings, and the proper o-rings to use here:
https://www.stangnet.com/images/stories/docs/sn95_TSBs/96-20-08.pdf

rolled up red Scotchbright on a drill with a piece of wire o clean the ID, \\, and string to clean the O-ring grooves.

Here is part of the o-ring table (old part number first, new part number second, Motorcraft 3rd)
391302-S100 W701993-S 3/8″ Spring Lock Coupling And Tube-O Fittings
391303-S100 W701992-S 1/2″ Spring Lock Coupling And Tube-O Fittings
391304-S100 W701994-S YF-1755 5/8″ Spring Lock Coupling And Tube-O Fittings
391396-S100 W701993-S 3/8″ Spring Lock Coupling And Tube-O Fittings
391397-S100 W701992-S 1/2″ Spring Lock Coup ling And Tube-O Fittings
391305-S100 3/4″ YF-1752 .Spring Lock Coupling And Tube-O Fittings

 

[zak]

So the part numbers in the post above were superceded yet again, and the ones listed for the 5/8 spring coupling didn't fit my SHO's evaporator even though a 5/8's disconnect tool was the only one that fit. You can still find them on Ebay and at obsolete Ford parts places but Ford has now gone away from green o rings and to ones that turn kind of red-purple when they hit PAG oil.

The correct O-ring part numbers are for the lower connection YF2960 1W1Z-19E889-JB and for the large connection 1W1Z-19E889-KB, these should fit all 89-95 SHOs and Taurus SLO and likely newer ones.

I will say that the Ford procedure linked above worked fantastic; using a braze rod bent around the correct lengths of rolled red Scotchbrite (1x3 and 1x4 if memory serves) to polish the inside of the evaporator inlets (soak Scotchbrite in PAG oil, low speed for one minute) and cleaning the O ring groves on the hoses (poke them through to the passenger compartment with dash and heater box removed) using a piece of kite string as dental floss all made pushing the spring lock couplings back together a breeze (you will need No. 12 and No. 8 springlock springs to replace what is on there, no Ford part number that I could find, clean the grove out with brake clean and a Q tip)

Important to clean the 0-ring grooves and the inside of the evaporator tubes thoroughly after the procedure above then **** everything up with the correct oil (PAG for 94-95 R134a systems) then they snap right into place. The evaporator was the only thing I didn't replace - did the blower fan motor, the fan itself, and heater core and the temperature control damper with NOS Ford parts and cleaned out all the dust. Commercial AC evaporator cleaner, foaming type, worked well to clean that part (rinse thoroughly and dry), I couldn't find a genuine Ford evap and splitting that part of the box was going to be too tricky/too much work.

 

[rubydist]

Just so everyone is clear - if you use Ester based oil in the R134a system, you do not have to remove every trace of the original mineral oil that was used in the R12 system - the two are compatible. You want to remove as much as possible, because R134a does not like mineral oil and it gets a little "lumpy" but if you get most of it out you will be fine even without replacing all of the lines, compressor, evaporator, and condenser.

However, the same does not hold true if you use PAG oil - that is not at all compatible with mineral oil, and will result in system failures.

Every system that I have converted, I only changed those lines or o-rings that were leaking, put in Ester based oil, vacuumed, and recharged. I have not had any failures of the converted systems. It is a good idea to change the dryer, as technically you are supposed to change the dryer every time the system is opened, and a new one will do a much better job of drying the cycling refrigerant than a 20-year old one.

However, you will find that you cannot put as much charge (pressure) in the R134a system as you had in the R12 system, That is why the capacity of the R134a systems are listed as lower than the identical system with R12. If you put that much R134a in there, you will find it blowing out of the over-pressure relief valve on hot days when the system runs continuously. That is why the R134a systems have a high-pressure cutout switch: to allow more capacity of refrigerant without blowing it out the over-pressure relief valve.

 

[itwonder]

I would only convert to R134A if I had to open up the system to replace major components, like the compressor, or all of the hoses. R134 does not cool as well as R12. There's a tradeoff between going through the effort to switch to ester oil and do the rest of the conversion steps, or pay more for R12. It use to be that R134 was really cheap, but the price has crept upward. A 12 oz can of R134A is currently $12.99 at AA. R12 is not hard to get, if you are patient, and it's not horribly expensive for the amount needed to recharge the SHO. I pay $20-$25 per can for NOS R12, and I seek out unrusted 16 ounce cans because they are usually priced the same as rusted 12 ounce cans. I've found the best source by far is Craigslist, unless you are a garage sale hound. All that said, this thread is a really good compilation of the conversion process, and thanks to all for sharing; it's a keeper!

 

[SHOdded]

Tech talk

 

[zak]

The time to buy R12 is when its -10 deg. out. I would never convert a system over its too much trouble, and the higher head pressures of R134a rob engine power. require safety ports etc.

Paid $8 for a 12 ounce can of R134a at Oreilly's yesterday, got 6 ounces to go in without turning on the engine/ compressor (vacuumed the system out overnight and verified it didn't leak back). Will wait for milder weather system is safe now though I expected the static pressure to be higher than the 40 psi I got (45 deg garage)