Thanks to all for the responses. The VOV sounds fascinating, but I think when my AC was working, it was actually working pretty well; both front and back units blew plenty of cold air. That's usually been right after Ford or I had just refilled the system. That did not last, as the system always leaked out slowly. A couple of years ago was the first time that I got the system sealed up tight. I replaced all the O-rings again, sucked down the system, recharged with what I thought was the correct amount of refrigerant. But this time, the pressures did not look right, and the system did not get nearly as cold as it did before even as the compressor kept running. A local AC tech suggests that the compressor is probably dying. With the sound that it is making, I am expecting the worst.
However, 3 years after that last charge, the system still shows the same pressures that it did before, so it must be properly sealed now. Blast! Now I have to take it apart to flush it out and replace at least the accumulator and compressor.
So it occurs to me that I should just take things apart and SEE what color O-tubes are in there now, and just order the exact replacements. This will have to wait until next weekend, as I got caught up in something this weekend.
I just looked at my AC compressor. It has a sticker on it just behind the plug. I had to rub some dirt and grim off the sticker to see what it said. Mine says FX-15.
I probably really messed up my systems. Hate to admit it, but I believed what it said on a box at the store. It said that R-134 was compatible with R12. All you had to do was screw their provided addapter onto the low side port. Then, fill up with R-134.
I did this back in like 2003 before I knew about this site. I have just been suffering without AC till now. Until this year and we have had 97 - 105 degree weather up here in Seattle.
So, I probably am in the boat of having to replace the entire system. Guess I will just tell my wife it is unrepairable. Live and learn.
xlt,
depending on your driving conditions, you may want to research VOV aka automatic adjusting orifice tubes, avail from RockAuto and other auto a/c parts supplies.
Sorry getting in late on this thread with a very long post. But I have encouragement and details for the DIY crowd.
I was a complete novice on A/C, had a dead system, and got the DIY correct on the first try. The starting point is an '89 dual that had an R134 conversion from about 8 years back. I did not know the failure mode, before starting or even after finish.
First step was to try the A/C booster charge and filled to the green zone. After I got my DIY education, I know that these low side dials can't tell you whether there is sufficient refrigerant in the system, only that there is enough to condense some into liquid phase.
Second step was to decide to do a no-excuses DIY project.
Pros: no billing rip-offs, results are in a known service level, can make low-level trade-off decisions, repeatable if needed, provides A/C education.
Cons: tool costs, time, might screw up.
3rd step, procurement. New Equipment and supplies:
- New compressor. eBay $100. My year uses FS6 (motorcraft YC-53, pn E7VY 19703A) which oldtimers say is a heavy duty design unfortunately cost-reduced into the FX-15.
- Clutch removal tool, $12. Need to swap the compressor pulley.
- Compressor oil, PAG46 double end capped. You'll need to get educated on oil. Mineral vs ester vs pag vs pag DEC, viscosity, etc. Replaced all (unknown) oil in the compressor and various system components.
- Robinair 15150 good to 50microns, $140. Now I have a really good vac pump gathering dust.
- Gauge set, $75. You're blind if you dont have this. Don't depend on low side gauge found on booster cans, or you're blind AND confused.
- Fitting, $16. Fittings were converted already, R12->R134 but the one hanging off the accumulator is pointed at the fender and I could not get my gauge hoses in there. Had to install a 90 degree fitting, now OK.
- O-ring kit for Ford systems, $11. Contained 40 to 60 rings. Although my system already had the R12 blacks converted to the R134 greens, this was a no-excuses DIY so they all get replaced again. Amazingly there are about 40 rings various sizes in a dual system. The one place not covered by standard kits was the compressor manifold which had something like a 7/8" diameter, had to reuse old.
- Spring lock tool, $12. Cant get your joints apart without this.
- Accumulator/drier, $45. Possibly could reuse old by vacuuming moisture out, but did not know failure mode, could have been contaminated by junk, this is a no-excuses DIY.
- Condensor, $170. Here was the major annoyance, bought a premium unit before I knew about parallel vs serpentine, only got educated after I compared the new versus old. The new one was a premium serpentine good for R12, during the previous conversion the old one had already been upgrade to parallel flow good for R134. If I had done the previous conversion, I would have known this already. Btw, this Modine unit is a drop in replacement for the aerostar.
- orifice valves. Bought a VOV for $15, did not use because it did not look compatible. Kept old rear which as green coded, and replaced dirty front red with oem from dealer.
- Refrigerant, qty 6 x 12oz, $38 total. Straight up, no additives.
- Can tap, $5 ???. This screws onto the 12oz refrigerant can, punctures the top, provides a valve to close a half empty can, provides a hose and fitting to attach to the system. Having the R134 fitting meant I could not flow the refrigerant through the gauge set nipples but fortunately the aerostar had the another low side port where I patched the set into while the can was using the other port.
OK, a lot of money (~$600), with a lot of unnecessary waste. But none of it was someone else's shop time. Tools are now paid-for capital equipment, future repairs cheap.
4th step, Do-it-yourself, get educated.
The first education was with condensor as mentioned above. The second lesson was with the gauge set as follows.
- In a static system (no operations, at ambient temps) a system that is filled so that at least SOME of the refrigerant is in liquid state, the pressure should compare to standard charts. Maybe down towards 50psi for cold days, maybe up towards 100 psi on hot days.
- With the pump operating, the compressor should be creating a low-side PSI and a different high-side PSI. Unrepaired, my low side initially cycled frequently between 25psi and 45, which is normal pressure but abnormal behaviour. Unrepaired, my high-side was around 50psi, normal would be above 200psi. This novice concluded that since my boost-in-a-can gauge said there enough refrigerant in the system, the compressor MUST be bad. Actually: not necessarily, could have just been undercharged.
- How much is enough refrigerent? Fortunately, I got the gauge set. I started with two pieces of info: 1) the dual system should swallow about 56oz, and 2) a R134 high-side should be in the 225->250psi range (200->225psi for R12). So I was concerned when I put in the first can, turned the system on it behaved as before: cycling frequently with high-side at 50psi. As I added cans the cycling stopped and high-side slowly crept up. 3 cans (36oz) gave 175psi, 4 cans (48oz) resulted in 205psi. I stopped there, but it seemed like another can should line up with that 225->250psi number. If you are heading above 250, you've gone too far.
- btw, the gauge set also reads vacuum. After I pumped down the system, watched the needle for a day to check for leaks. Not the same as a high pressure test, but if it can't hold a vacuum it most likely can't hold pressure either.
5th step, measure the result, pat yourself on the back.
- Worst performance will be at idle, stationary. Measured 58 degrees at the ducts on a 85 degree day. OK but not impressed.
- Get the van moving and its a big improvement. Out on the road in 95 degree ambient, so cold had to leave fan on low and sometimes blend in a little heat.
Final note: Don't depend on any info I supplied here. I'm not a professional, and have no formal A/C training. Do your own homework.
Admin, is there a chance we can post this on the sticky links (or whatever they're called)?
My problem when I last did mine was not of pressures; I got all the right pressure readings for the low and high sides. My system just would not cool very well, even while driving on the highway. Then the noises in the compressor started...
Great Info and nice writeup RojoStar !
I could disagree with a few details, but not even near enough to bother with.
I was all good, but I especially liked this part:
...Tools are now paid-for capital equipment, future repairs cheap... - Robinair 15150 good to 50microns, $140. Now I have a really good vac pump gathering dust. Excellent choice! - Gauge set, $75. You're blind if you dont have this. Absolutely! Don't depend on low side gauge found on booster cans, or you're blind AND confused.
Excellent advice for anyone who DIYs many of their own repairs. The cost of the tools ate up any savings on THIS repair, but they will pay for themselves with the money saved on the NEXT repair. Everything after that is money ahead.
AC repair isn't rocket science, but some knowledge and the proper tools are essential.
PS. Sounds like you bought the can tap with a hose attached. Look around and you will find one with no hose and the proper fitting for your manifold gauge hose. AutoZone carries them and they are actually good quialty, all brass.
Also, I'll bet you'd see a substantial improvement at idle if you replaced the fan clutch. Converted dual systems can be a bit weak at idle but I'll bet it would help, especially since you now have a PF condenser. It should perform as well as a factory R134a system.
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Dude! Stop posting AC p*rn! This is a family Forum. Those pics make my leg tingle.
I'm digging the Robinair vacuum pump. About 5 CFM? I have it's 2.5 CFM, single stage older brother. It's about 27 years old now and is my "mobile" unit. It goes into the car trunk/back of the truck when I make a remote call. It's been very well used and sometimes abused and still pulls 160 microns easily, just takes a while.
I see your gauges are multi-refrigerant (R12 hoses with adapters for R134a), but the yellow hose is on the "R12" port of the vacuum pump?. Did you get an adapter to connect your yellow center hose (R-12) to an R134a supply?
It would be 1/4" MFL (male, screws into the yellow hose) to 1/2" ACME female(screws onto the R134a source fitting).
Any "screw on" R134a can tap you find will be 1/2" ACME male, as would any larger R134a cylinder.
A "side tap" can tapper might be 1/4" MFL as to cover multiple refrigerants.
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Yes sirs, this is an area where the novice will blow some brain cells. The professionals would have a deeper tool kit and have the best style for using it.
Just for reference here is some equipment that was in play on my project, not all used, not every thing useful. As pointed out the gauge set (photo northwest and north) is R12 but ships with R134 adapters (west) that plug onto my system that itself was retrofitted from R12 to R134 using a fitting (south of center). Meanwhile refrigerant (southwest) comes in cans with ACME threads and a metal seal.
Coming into the project I had this booster can (east) with a "reusable dispensor" that probably sat on ACME threads, but I was also unsure of what sort of puncture capability. This was moot because the dispensor was unfortunately the cap on the still pressurized can. The gauge set also came with an ACME to R12 adapter (southwest of center), also useless because it had no puncture cability. So another hose was procured.
As pointed out I made an unfortunate choice of (R134) end style and could not hook up through the (R12) yellow line of the gauge set. My butt was saved when for some reason my system had two low-side ports, one used for inbound refrigerant, the other for the low-side gauge. One advantage to a short direct connection for refrigerant is I could gravity feed (the first can only) into the system. IMO one would like to hang both the vacuum pump and the refrigerant off the yellow line.
btw, Robinair 15150 is two-stage 1.5CFM 50micron, rated for continuous use, two nipples (+adapter?) to cover 1/4", 3/8 flare, ACME. Perhaps I could hang the refrigerant off the second nipple, avoiding procurement of a Tee fitting and another hose. The professionals will scoff at the CFM because they are on the clock. Even though it pumped down the dual system in just a few minutes, I left it running overnight to assure the system boils off any moisture.
Only 1.5? That's a good choice for mobile AC work, it just "looked" like a higher capacity pump. It's big physically, my old 2.5 is a good bit smaller.
With this can tap : http://www.amazon.com/Mastercool-855.../dp/B000LQODJC and your R12 to acme adapter, you could have connected right to the yellow hose. That's the adapter I was asking about.
To connect the refrigerant and the pump at the same time you would need a 4 hose manifold with valves in both center hoses. I think there are also add on valves that will let you do that with the 3 hose manifold. It's a neat setup, but not really necessary. Most folks just swap the hose from pump to supply.
Nice work and good pics!
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This is a family Forum. Those pics make my leg tingle. 
I have it's 2.5 CFM, single stage older brother. It's about 27 years old now and is my "mobile" unit. It goes into the car trunk/back of the truck when I make a remote call. It's been very well used and sometimes abused and still pulls 160 microns easily, just takes a while.
