I have been unable to find a new or reman R12 AC compressor for my FD and did some forum digging to learn that the compressor from a 93 Corolla will work. I ordered a new Denso one from Rockauto but now that it showed up, I see that it’s not the same. No possible way to connect the hoses.

Doing more digging, I noticed O’Reilly cross-listed FD compressors with a 1994 Toyota Tercel, which apparently has reman compressors available. Pictures look a lot more like the FD compressor than the 93 Corolla compressor: https://www.4s.com/en/ecatalog?year=1994

Can anyone confirm which Toyota compressor will actually work before I order another? A part number or something would be helpful. Any thoughts on compatibility of this Tercel compressor would be appreciated also

 

I got a new aftermarket Nippon Denso compressor for the FD from these guys - https://ackits.net/product/14-3662nc/

Working great so far, restored my A/C system this past summer. BTW, if you were hunting for an "R12 compatible" compressor for your FD, you won't find one anywhere - all compressors built or re-manufactured these days are built with HBNR (green) seals & O-rings for compatibility with R134A and other modern refrigerants. But that won't stop you from using one on a system charged with R12 - same seals are fine with R12. When restoring the system, you just need to ensure the refrigerant lube type in your system is compatible with your choice of refrigerant.

 

^ That site is a great find! I want to pick up a new compressor for my 1995 for the eventual day when my compressor fails while I still can. I plugged in “1995” into the settings for FD and several options came up, some seemingly not available. Any idea if the one linked above will fit a 1995 (a MANA system, as far as I can tell from forum info)?

 

I'm about 99.9% certain that the compressors used on all the USDM FDs were common to the MANA and Nippon Denso A/C systems, so it should fit your '95.

 

The ports on the compressors are different between the factory installed denso system and port installed mana system. The mana will have larger orifices. The denso smaller. Same goes for the lines. The compressors are identical other than the port size configuration. The place that Pete listed also sells rebuild kits for them. I have used one of their rebuilds on an older Denso with great success.


~ GW

 

Thanks for the good info. I had a bad feeling that it would not be that easy.

 

Thanks! Did you buy for a MANA or Denso system? Just want to make sure the ones they sell will fit.

 

Mine was originally a Denso system, but because I had to restore everything forward of the firewall, I'm using a generic aftermarket condenser, aftermarket dryer (that fit in the OEM bracket), and had to run my own A/C lines & service fittings to work with the single turbo.

 

I'm seeing conflicting information about whether MANA and Denso compressors are identical. This thread says they are identical, but folks here are saying the ports are different sizes?

I measured the ports on my MANA compressor today and got the following. Can anyone check a Denso compressor?

Side port:
19.5mm outermost ring / 14.5mm inner ring

Top port:
16.7mm outer ring / 11.7mm inner ring

Looks like there are multiple 'steps' in each port that get progressively smaller but these are the extremes

 

So you got me thinking, since it’s been sometime since I’ve restored both systems. I measured the Denso and mana r-12 compressors from a 93 year. Good news is they both have the exact same orifice size. The line fittings on the rest of the Mana r-12 system are in fact bigger than the denso r-12 line fittings. Now if my memory serves, the 94 - 95 134A equipped cars will have different size ports on the compressor. If someone with a true 134A compressor ( Check the tag on the back ) can measure the ports, that would help in identifying the difference. ( I changed my calipers to MM but in the future it’s better to measure in thousands of an inch)


~ GW




DENSO R-12













MANA R-12

 

https://www.rx7club.com/3rd-generati...dings-1138256/

https://www.rx7club.com/3rd-generati...1117979/page3/


These two threads cover the compressor a bit including the 134a compressor. Unfortunately they do not have any port measurements in them. Here is also a pic posted of them side-by-side. It appears to me that the ports on the 134A compressor are bigger. Hard to tell from a photo though. Maybe Dale can measure the 134a compressor when he has a chance.

~ GW

 

I found another thread that confirmed the r134a compressors have different port sizes, but with these measurements I can now know the Mana and Denso R12 compressors are identical, port size and all. I'll go ahead and order from the Arizona mobile AC company that Pete_89T2 found. Thank you everyone for helping me get AC working before my first summer in Texas!

 

I got the new compressor from the Arizona AC place that was mentioned. It’s a 134a compressor with some machined adapters to bolt up in an R12 system. I hope it still works with R12… looks like it uses a different oil, for one. The side port adapter also adds half an inch of thickness making it very difficult to install. I had to drop the compressor into place, twist it, get a bolt through the side, then screw in the 4 retaining bolts. Kind of a pain but it does fit. I’ll know if it works once I get rid of my MANA drier and splice in something else. This is just for everyone’s reference

 

Interesting that it has those adapters!

If you want to use it with R-12 it has to have a compatible oil in the system. Most new compressors come with the oil pre-filled, you would just turn the compressor over and turn the pulley until you get as much out as you can, put some of the right oil in there, pump it through, flush out, etc. until you get it all out. Fill with proper oil and done.

They probably also upgraded the seals to handle 134a also.

In general, 134a is more picky than R12, you have to have the right o-rings, barrier hoses, oils, etc. The good thing is most of that stuff is backwards compatible, an O-ring that works with 134a will work with R12, for example.

Dale

 

Sounds like I should remove it again and drain the oil... I wish I'd thought about that before I spent an hour getting it back in! I do have all new O rings from Mazda that I installed 2 years ago, so probably not r134a rated. I want to stick with R12 because my experience with r134a in an r12 system is not good in Texas heat and stop and go traffic.

I heard that running R12 in an r134a compressor can damage the compressor seals due to r134a compressors running a higher pressure, so I am a little worried about having a compressor labelled r134a and using r12. Any thoughts?

 

If those O-rings are green and undamaged, they are most likely made of the HBNR material, which is compatible with both R134A and R12, so you can use them no matter what refrigerant you decide to use. As for the lubricants, R12 systems typically come with a mineral based oil, while R134A systems use a PAG based lube - those two lubricants should not be mixed. If you're restoring a system and NOT starting with a 100% "dry" system (i.e., all parts are either new or were properly flushed of any lubricant), your best option for lubricant is a POE/Ester based lube (e.g., any quality Ester-100 will work fine), as it is compatible with mineral oil, PAG lubes and is compatible with both R12 and R134A refrigerants.

So you'll want to bench drain whatever lube happens to be in your new compressor, and "flush" it with fresh Ester lube. Bench flushing involves filling the FSM recommended amount of Ester oil to the new compressor after you drain the stuff it came with, rotate the compressor shaft clockwise a few times to circulate the lube and then drain again. Rinse & repeat this process a couple of times until you see nothing coming out but the fresh Ester oil. Install your compressor and a brand new dryer, close up the system, pull a vacuum to at least 29~30 inHg, and check that it holds a vacuum. I like to see it hold a vacuum overnight; if it does, it's ready to charge it with the refrigerant of your choice.

Nah, if anything the opposite might be true - R134A operates at higher head pressures than R12, so there's a possibility that if your R12 compressor has a mechanical pressure relief valve built into it, it might blow open when running on a very hot/humid day, especially if the system is overcharged slightly. Seals won't care otherwise, because the HBNR seals used for R134A will work with R12 just as well.

 

That's interesting about the adapters. When I got mine from AZ Mobile A/C, it didn't come with the adapters, though the compressor looks otherwise identical, and is R134A rated/labeled. I ordered mine by phone to confirm I was getting the right parts, and IIRC correctly, he asked me if my system & plumbing still had the R12 compressor fittings. To which I said it did, since I used the compressor pad fittings & pipe sections ends from a used set of Denso R12 hoses to fab up my custom lines. That's probably why I didn't get the machined adapter bits.

 

Very interesting, and encouraging for us 1995 owners! Thanks for sharing this info.

I'll reach out to the Arizona dealer and see what they have to say about a compressor for the R134A MANA system.

 

If I were to buy a brand new compressor for my 93 touring USDM, is there one that I know would 100% be compatible with mine? My AC compressor is tired, and needs to be changed. Think I have a leak in the system as well that I will try to find as well, but want to buy one just to replace. When I bought it it worked intermittently and now doesn't work at all.

 

My concern about retrofitting with a 134a set-up was the diffuser in the dash.

Would there be rings (etc.) in there that need to be attended too?

I understand that the diffuser can be removed without removing the dash.

But can an r134a diffuser be put in as a replacement?

I guess we are hearing that the r12 diffuser would at least have to be carefully drained.

I have also heard there is an alternate oil that can be used in both systems.

Is that so?

 

Don't forget a replacement refrigerant for existing R-12 systems exists. R152A (computer duster) worked great for me.
Replace expansion valve on evaporator, replace joints with new green O-rings, flush compressor with Ester oil, add some ester oil to drier, charge with ~12oz of R152A. All for the less than a charge of R134.
Dash removal wasn't required to pull the evaporator once the engine bay lines were detached.

 

For my part, I'll need to pull the compressor out again to drain the oil. That was a complete oversight on my part, and I thought about it later that day. I was just eager to see if it would fit!

Since my system does not seem to have HBNR O rings (the ones from Mazda were black) and since I need the best possible AC performance, I'm going with R12 and I purchased mineral oil to use. My former-mechanic grandfather gave me several cases of R12 so supply isn't an issue. My last r134a conversion worked poorly at lower speeds and I live in Texas, so lots of hot weather.

I am currently having a local shop cut and splice my drier hardlines to accept a Denso drier. Once that's done and the compressor is refilled with mineral oil I'll pull vacuum and see how my system looks.

I did not realize you don't have to pull the dash for the evaporator. I thought I had to and therefore was going to skip replacing the expansion valve. Should I also replace the expansion valve alongside the drier?

 

I think one of the expansion valves is NLA.

The whole AC evaporator is designed to come out with the dash in place. Mazda installed the AC systems at the port on most FD's to save on tax so it was designed for a straight forward installation. Also worth pulling because it's usually full of crap - dead leaves, etc. When the system is open is the good time to pull that out.

Dale

 

I actually had it out 2 years ago when I pulled the dash to replace a bad heater core. At the time I pulled the evaporator out and made sure it was clean and also tested it for leaks. I believe the same Arizona AC shop sells the MANA expansion valve but it wasn't on my list to replace. Is this it? https://ackits.net/product/18-2251/

 

The whole AC evaporator is designed to come out with the dash in place.

Had to read this twice. Only got as far as "designed to come out with the dash".