AC parts availability and MANA vs Denso AC
 

Hey everyone -

Been a few threads on this recently, figured I would document a few things.

First off, you need to see what system you have, MANA or Denso. MANA is MAzda North America and was installed at the port when the cars came over from Japan. The receiver/dryer (that's the soda can-size thing up near the battery and in the intercooler duct) has 2 lines going to the top. If the drier is black, has a bracket that's welded on, and has a small box with a sight glass on the line, it's a MANA system. If it's a silver drier with a bracket that clamps around the drier and the sight glass is attached to the top of the drier, you have a a Denso system.

The only component that is shared between the two systems is the compressor - that's the pump that's driven by a belt. All the lines, the evaporator under under the dash, the condenser up front, they are all different. The threads on the fittings and fitting sizes are totally different.

Very few if any of the stock parts are available from Mazda any more.

Aftermarket wise, the Denso driers are available nearly anywhere for less than $20. They are typically available at local parts stores. The MANA drier isn't available anywhere for love or money. You could have a shop alter the AC lines and put in an aftermarket drier or maybe have the drier restored, there are places online that supposedly do that.

The exapansion valve in the evaporator seems to be available for both the Denso and MANA systems.

O-rings for each system are different sizes, I have a chart somewhere listing the sizes. I'll try and post that up. But, the O-rings are common AC o-rings, you do need to verify that they are the exact right size.

If you have a hole in a line, many AC shops can weld or braze the hole shut for a minimal amount. As the lines aren't available that's going to be a good way to go.

Big thing here - if you are pulling the AC out of the car, PLEASE sell the parts and keep them in circulation, don't just throw them out! The FD's AC, when working right, REALLY works well.

Dale

Thanks, Dale. I didn't know the dryer was so interchangeable. I have a Denso system for sure. The expansion valve and evaporator are listed online at many sources but when you call them they all say that they don't actually have it. :(

Good info.

Do you feel like your AC blows pretty strong on fan setting 4?

Mine seems super weak.

Mine blows very well on setting 4. Right after this latest R12 recharge, I can leave it on "2" and it's plenty cold in the car. Of course, the weather hasn't been too bad here in San Diego lately though.

That's one thing I need to address on my car, the fan speed seems SUPER weak. I'm wondering if the fan itself is wearing out or the fan isn't getting enough voltage. I haven't had time to troubleshoot it. On speed 1 you can BARELY feel air coming out of the vents.

Dale

about 4-5 years ago I replaced my Denso condenser with a brand new one for quite cheap. I decided to look recently and didn't see them available anywhere anymore? have you guys seen any sources for them as of late?

Are the AC compressors the same even if it's R12 or R134a? My system is R134a; can I use a compressor from an R12 system?

Box of Bricks
 

Attachment 727688


I just acquired a box full of compressors. Three of them are Denso R12 compressors. Are these the ones used with the Mana system? They box came from the UK.

As stated above, the compressors are the same. The compressors are made by Denso but both systems use the same one.

Supposedly there is a difference between the R12 and R134a compressors, they are labeled as such on the back. If you're going to use an alternative refrigerant like Dust-Off (R152a) I don't think it really matters which one you have.

If you are going 134a, it's worth flushing out the oil compressor oil and putting in newer 134a compatible oil.

Dale

La Differance
 

Thanks, Dale.


The compressor on the left is an r134 out of my 99 S8. The others are the Denso R12. The line connector ports are different, as you can see. The shop put in an r12 as a replacement and found the S8 lines would not hook up. Luckily a used r134 also came in the box. Which is now hooked up and working. The electrical connector attachment on the top seems different as well.


I wonder, in regard to Quickfini's question above, if a rad shop can change the adaptor on the end of his R134 line so that it can fit on an r12 pump? I think the lines have built in sensor that look like they would be troublesome to remove and adapt to another set of lines. So I wonder if just changing the ends is a consideration?

Would have helped if I looked at your picture :).

Interesting, the 134a compressor IS definitely different. The line fitting in the back is different as is the wiring and such at the top. That wiring eventually goes to the magnetic clutch at the front of the compressor, I think there is also a sensor there that will cut it off if pressure is too high or something.

Makes sense that the sensor up top would be a different design as 134a run different system pressures.

Bad part of this is there's yet another wrinkle to what AC parts work with what.

Dale

All this AC nonsense is making want to just rip it out and be done with it. Either can't find parts or something is not compatible with the other. Aaahhhhh

That's really why I'm trying to document some of this, so people can go forward with that knowledge and get their systems working.

The AC in the FD works REALLY REALLY well, it's ice cold, the engine doesn't bog down when it's on, it really does work well. Sad part is Mazda did a number of weird things, like having 2 different incompatible systems, making the run for the AC lines goofy, and making the drier on the MANA systems a "limited time only" for part availability.

Dale

So what's the best course of action to us with the MANA system
Go custom if we need a new drier/receiver
Customs the lines, reusing old parts.
Is there a place where we can buy expansion valves for MANA and pressure cut off switches / sensors

As of now, you could have a place refurbish the MANA drier, I know there are shops that do it for vintage cars. Or, you could have a shop fab up custom lines and a drier.

I would like to pursue having a MANA drier refurbished at some point, finding good used ones would be easy. The shop cuts it open, cleans it out, puts in fresh desiccant, welds it up and paints it. It's just like brand new when done. In theory :).

Dale

Im purchasing a car that's had a/c system removed. No compressor, drier, or condenser or lines to my (or the current owners) knowledge. I MUST have A/C as I plan on enjoying this rx7 in south FL. How difficult and costly will this undertaking be realistically? If I find a compressor, can I just use/convert to denso everything else to find parts easier cheaper using custom lines? The car is a 93 R1... was the mana or denso used on this? Sigh... :(

Thanks for your very informative posts on this subject!

- Kevin

Under the dash parts.
 

Is the evaporator still there behind the glove box? That might be the tricky piece to substitute. But may have been left in place.

Clutch this.
 

It seems the clutch assembly on the front also seems different, but I wonder if the clutch would obey signals regardless of which version car it is in?

Most likely the car had a MANA system in it. Your best bet would be to find someone selling a complete system as trying to find all the parts piecemeal would be a helluva job. Clean all the lines up, put new O-rings everywhere, fresh oil in the compressor and a new receiver/dryer or rebuilt one.

In the FC forum is a long thread by JackHild about using R-152a for refrigerant which is computer dust-off. The thread has LOTS of great info about getting your AC going again.

Dale

All the clutch itself does is engage when it gets 12v, which is about as dirt simple as it gets. The trick is the pressure switches that shut the compressor off for high or low pressure, those are most likely different.

Dale

Bringing back an oldie here. I'm trying to get my compressor clutch to engage and even when applying 12v the clutch doesn't engage. Based on Dale's notes I appear to have the MANA system. Do the pressure switches still override the clutch engagement even when applying 12v where the relay plugs in? Obviously I'm trying to get mine going again and was trying to take the relay and a/c switch our of the equation to get the clutch running so I can charge the system. So far I can't get the a/c system to take any coolant. Its been empty for years as it was disassembled and taken out of the car long ago.

I think the switches are down stream of the relay, the wiring diagram in the shop manual should clear this up.

Dale

The first diagram looks to me like adding voltage at the relay should engage the clutch, however I'm not clear how the 2nd diagram ties in. Its the one with the pressure sensor noted.

I'm just a laymen reading these things though. Does it look the same to you?


https://cimg1.ibsrv.net/gimg/www.rx7...d959612539.png


https://cimg3.ibsrv.net/gimg/www.rx7...859253254f.png

Real good info. I deal with this all the time when customers ask me to fix their ac and provide the wrong lines. Literally nothing is interchangeable except the compressor. In a bind I've cut the fittings off and welded them to other lines to make things work because the Mana stuff is no longer available.

I have a MANA dryer if anyone needs one, its off a 95' with low miles. also have the lines for it.