Is There No End to This?
 

As written previously on this forum, we have had our '94 FD's engine, turbos, wiring harness, engine mounts, etc, etc replaced and are in the middle of break-in at about 400 miles. Unfortunately about a week following the R-12 Freon refill and testing, the A/C no longer cooled. Turns out that the A/C compressor was leaking that very expensive stuff and it all went away. So back to (another) shop for repair. A new Denso A/C compressor was obtained. But "it turned out" that the OEM receiver-dryer from the original factory build (which used a Mana compressor) was not compatible with the new compressor, so another one had to be ordered (from Texas). We are still waiting for our car, which has now been down for about 3 additional weeks.

I was told that the vacuum procedure applied to the original compressor before the initial R-12 refill probably reverse-stressed its seals, which had always been under positive pressure, causing the leak. Has anyone else had such problems with an A/C system which had worked (for us) for 23 years with no maintenance required?

Schroedinger's cat. Was it working 100% before you fixed it? I haven't had such AC trouble, but touching old working things is always risky. You might have revealed the weak links in the system.

To answer your question though, no... There is no end. :)

Yes, before the engine replacement, it went 23 years with absolutely no problems.

Ha, probably true.

It is not uncommon for seals in an ac system to hold a vacuum, but not pressure and vice-versa; it depends on how the individual seal is designed. All of the elastomeric seals in the ac system will take a set with time, and may not re-seal properly once disturbed--this is especially true for the O-ring joints. I cannot say if the evacuating the system resulted in your loss of seal due to stress, but I can tell you that I've had to replace the shaft seal on a couple of high-mileage compressors. Do you know what type of oil is in the system, and if it is in the correct amount (not just a guess)?

Once everything is sorted, your ac system should remain stable for a long time.

I am curious as to why the original dryer was not deemed compatible with the new system? It was an R12 system, correct? Are they claiming a difference in oil type or desiccant? Whatever you do, keep that old drier! They are getting scarce--and it can be rejuvenated. (Regardless of what you might have been told.)

Another thing you might do before you put R12 back in your system is to do a shakedown run using an inexpensive $5 a can alternative refrigerant such as ES-12 or equivalent. Prove the system works and then recharge it with R12 down the road, once you've determined that everything is good to go. There is no harm in doing so (again--regardless of what you may otherwise be advised) and you could save a considerable amount of dough in the process.

or stop using the R12 altogether... yeah plenty of people will tell you you must retrofit, use different compressors, condensers, and everything under the sun, yet that isn't true.

switching freon also allows you to work on the system yourself, instead of relying on a shop to bust your balls every time theres a small issue.

I know zip about the type of oil in the system. It has had the OEM charge in 1994, a new charge of R-12 with oil at an A/C radiator shop about a month ago, which leaked a little of the green marker on our garage floor shortly after the charge, and now has a new re-charge with oil by a second shop. Oh yeah, the last A/C guy said he had to replace the battery too. Time has been spent this go-around on checking for leaks for at least a couple of days... hopefully we will have the car back this afternoon.

Presume you mean switching from R-12 to R-134A. We are choosing to stay with R-12 since its cooling capability is greater, and the FD seriously needs really good A/C due to high heat transfer into the cabin. Also I have heard that the molecule size of R-134A is smaller than R-12, which is more prone to leaking in an older system with older seal designs.

I have a question about your new shop's abilities:

How exactly is the drier that was already on the car now magically incompatible by changing the compressor?

The lines are not made to the drier, they bolt to drier. So, the ends that go to the compressor would not be different...

Now, the two different drier types are not interchangeable because the lines have different style fittings. So, you can't put the wrong drier on the car if you wanted to unless you fabricate lines or machine the drier.

I can only speculate that the problems you are having are caused by lackluster technicians. I could be wrong, but of all the things that can go wrong, the A/C system is one of the simplest ones on the whole car. It should not be that hard for a shop to diagnose and repair it.

Vince

i've converted many cars that ran R12 to R134a and R152 and the cooling capacity isn't nearly as bad as it looks on paper. my FC would get cold enough that i had to turn the a/c down a number of times. you can ask others here who have converted rather than take just my word for it.

^ It's kind of hit-or-miss...I did several and most worked really well...in fact my B2000 would still blow ice-chips under the right circumstances.
Helped a friend do his old Toyota Corolla and...while it was 'cool', it definitely wasn't the COLD that we expected.

Is you car still at Steves?

Words of wisdom.

That was apparently not true, sorry... some confusion during labor on the system by the tech. He was able to use the existing receiver-dryer after all. Job is complete, car was returned to our mechanic yesterday and is now at home. Wife states that "it works like it did originally" (i.e. since new). Total cost of A/C work (including replacing the battery for $89) was $1354. $440 for labor, parts breakout as follows:
Compressor: $600
1.75 lbs R-12: $175
ND-7 mineral oil: $15
Flush: $35
O-rings: $4
Battery: $89

Nice that it now works. I'm lucky, I guess, that mine still functions as new (~73K miles) and has never had to be recharged.

I still have most of the 20-lb bottle of R12 I bought ~20 years ago. That has been used mostly to top up the somewhat leaky aftermarket AC system in my 324K mile G30 van that tows my racecar.

If you drive old cars, especially sports cars, they will nickle and dime you to death. The FD is worth it though because it will return more smiles per mile than anything else :D

IMHO the A/C would still be working just fine at 113K miles if we hadn't needed to replace the engine. It never gave a problem from new in Sept. '94 to the engine change.

I'm sure you're correct - a twist on the old adage: If it's not broken, don't disturb it!

what compressor did you buy? Where ? Curious cause i may need one also

Yeah...don't touch things that aren't broken...sure way to MAKE them break.

Isn't there some lightbulb at the Denver Mint that has been on continuously for something like 70 years now? They don't DARE touch that thing!

The compressor is a new Denso, as I wrote above; I asked Steve where it came from, but he wouldn't say. My parts manual lists it and the Mana compressor as the two units used by Mazda for the FD. If you want to contact Steve at his shop in Costa Mesa, he claims to have contacts with other A/C specialists around the country. His contact information is:

STEVE's D & S Auto Air
Auto Air Conditioning & Heating Specialist
1638 Pacentia Ave. #B
Costa Mesa, CA 92627
(949) 645-7802
(714) 835-3666

Thank you for the update

Did the shop that did your engine mess with or discharge the AC? If so, that is totally unnecessary when removing and reinstalling an engine. If they did, then they are ultimately responsible for your totally unnecessary cost. Just my opinion.

The original problem was a coolant leak in the cabin from the heater core. The FD configuration requires both the heater and A/C lines to be disconnected in order to remove the heater core. The A/C system was left empty until after the engine was replaced due to a separate problem: an engine coolant seal had failed, allowing combustion gases into the coolant system. The first refill of Freon after engine replacement leaked out because the compressor seals failed. I was told that pulling the required vacuum on the 23-year-old compressor prior to refilling it probably caused the leak. The compressor was replaced and the Freon refilled again, and the second time was "the charm." So far the A/C is working well, as is the new engine, turbos, wiring, etc, etc. The total cost of all the work including engine replacement was just over $14K including labor, parts, and Freon. And the car was down for about 3 months.

Your FD is pretty clean. Keeping it and doing all the required major maintnance is the right thing to do. You wont regret it

What's the consensus on using Enviro-safe "R134a" replacement?
I contacted the manufacturer and they said something about how the R134a label was just something to get past regulations but it's a direct replacement for your R12.
Is it compatible with the Mana (or Denso, I forget which one is for '94 touring models) compressor and dryer?
I think the o-rings have to be replaced but I have no idea regarding the rest of the system...