ploplen

I used the diagnostics connector to pull the error codes for the AC!
And I got code 15, but what does it mean? Can't find it anywhere.
All I know is that my AC is not cooling much.

DaleClark

iTrader: (55)

I don't think there's a diagnostic system for the AC. If you check the ECU codes, 15 is a bad oxygen sensor.

Dale

ploplen

According to this page there is,



And I used those pins so it's definitely not a PCME code.

JM1FD

iTrader: (1)

There is neither a TAC nor FAC terminal in the diagnostics box on my 1994, and the wiring diagrams indicate that the positions are not populated. The hole is there, and the position is on the label on the inside of the lid, but there's no little metal terminal in the hole.

What year is your car? Was it built for North America?

I have seen *ONE* picture of an RHD car that had an A/C control head unlike anything we ever got here in the states. Instead of a **** to twist to select air output location, it had a button which would cause the system to rotate through the positions, and light up a light next to the icon denoting position. It is possible that that was a completely different system and had a diagnostics capability.

ploplen

Interesting, I have a 1994 Japan build.

My car looks different from the workshop manual. Air output location selector is a **** that can be turned but small lights indicate the position. (So you don't know the position if there is sunlight present.)

So maybe I have to learn Japanese to solve this problem...

JM1FD

iTrader: (1)

*VERY* Interesting. So, when it blinks out the code, where is the light that flashes? Mind posing pictures of your control panel? I've never seen a good pic of that control panel.

So...on to your problem: not cooling well. Is the compressor running? Is the big fat line that goes from the firewall to the compressor cold? If the engine is cold, and you start it and turn on the system, is the air cooler than after the engine has warmed up?

From what I've seen, when an HVAC system can flash out a code like that, it will only give you errors from the sensors and actuators on/in the dash, nothing pertaining to the refrigeration side of things. About the only problem under the dash that isn't refrigeration related that would cause this would be a bad thermoswitch (possibly a thermosensor on that system) or the blend door actuator or door itself has gotten stuck in the hot/warm position.

ploplen

I ground the TAC terminal in the diagnostics connector and put a light between FAC and ground. Just like I do with TEN and FEN to get the ENgine codes (JDM don't have check engine light).

Can post a picture of the panel tomorrow night, now I'm about to sleep.

Will try the other things you suggested too. I'm thinking that maybe the refriegent is out, feels like something that could be detected.

JM1FD

iTrader: (1)

Ooooh. Neat-o. Didn't know either of those operations was a bulb-it-yourself deal.



A low refrigerant condition could, in theory, be sensed by the system, but that type of functionality didn't seem to be in production cars until the early 2000s. I would suspect that if there's any code relating to a low refrigerant condition it will be a complaint about the evaporator coil not getting cold enough within a specified time range....but again, that seems like sort of an advanced functionality for a car of this vintage...especially considering how primitive the engine computer is.

One other idea, and I'm not sure how you'd go about finding this info, would be to see if this car shares the A/C computer with another car...codes could well be the same. Mind you, this isn't a totally insane notion...the North American RX-7s seem to the airbag computer (or at least the guts and the error codes) with a variety of Ford products.

ttmott

iTrader: (1)

There were two different AC systems installed in the FD RX. The US cars (at least most of them) had the systems installed after arriving in the country; these were installed by Mazda North American Operations (MANA). The non-US cars were factory AC cars with Nippondenso systems. Quite possible the factory AC cars included the diag. One would have to research the Japanese Service Manual to determine for sure.

Dale Clark has done quite a bit of research on this - you might PM him for more info.

JM1FD

iTrader: (1)

Parts diagrams don't make a distinction for any of the control electronics. Only difference between MANA and Nippondenso is in most of the refrigeration components: evaporator box and everything inside, condenser, drier, and the lines.

ploplen

Here is the pic of the HVAC control,

Note that some indicator lights are on. I noticed that both the "American control" and the one I have are mentioned in my Japanese owners manual, but what are they saying about them....

I got a feeling that the air was slightly cooler with AC turned on, but only slighter. The big fat line is not cool, magnetic clutch is working and so is the extra fan input. I seem to have insufficient refrigerant or bad pressure (looked in the sight glass).

I guess that should be fixed before moving on.

And a bonus picture for you JM1FD, it's the instrument panel, I believe it's slightly different from the American panel. (Airbag, seatbelt and E-brake lights are out in picture, headlights in blue are hardly visible).

JM1FD

iTrader: (1)

THANK YOU! That's great to see a detailed shot of it. It looks like a full on set the temperature and let the computer do the rest type climate control system. No?

It could be any number of things, but being low on charge is indeed the most likely culprit. You can't rely on the sightglass if you've got R-134a in the system. If you have R-12, then yeah, the sightglass is a fairly reliable indicator....no bubbles/foam means the charge is correct.


Yeah...slightly different, but not the HUGE difference like the HVAC controls.

DaleClark

iTrader: (55)

Yeah, you have an automatic AC system that was Japan-only. The US systems just have 4 fan speeds and a temp control, not the digital control to set the temp at and the system automatically adjusts temp and fan speed.

The knowledge base on the auto AC systems is pretty much zero. But, if the AC system is generally not working, it could just be a standard AC problem, like low refrigerant, that an AC shop can diagnose and fix.

Dale

ttmott

iTrader: (1)

Dale - any info on the diag. port related to this? The OP is getting some error code...

ploplen

Yes, it's of course possible to control manually.


In the workshop manual they used the sight glass for both, but you have bad experience from R-134a systems?
How do I know which system I have?

Dale, ttmot mentioned you had done some research in this area, via the japanese manual?

This refilling refrigerant business, is better left to the professionals and not done at home?

JM1FD

iTrader: (1)

It is fairly common knowledge that the sightglass can't be relied upon for R-134a. A lot, if not all newer cars don't even have sight glasses anymore. Our cars were built in the transition period, so they just left 'em on.

Since you don't know the full history of the car, the only 100% true way to determine refrigerant type is with a refrigerant identifier. But few people have those, so the other way is to look at the service ports. R-12 service ports will have threads on the outside, R-134a ports will be a quick connect type....no threads on the outside.

For most people on this forum, I'd say take it to the professionals, but it seems like you're WAY above the forum average. Read up on it, see if you're comfortable with it, and if you want to buy the tools, go for it. It isn't really that difficult, it just requires a bit more thought and care than most auto repair tasks.