Guys - I didn't want to start a new thread but there's not been something similar for nearly a year. I've owned this FD since the end of '05, but have only had it on the road since the end of '08. I bought it crashed with front end damage.

I'm trying to get the A/C working, it hasn't since I owned it. So, I put R134 adapters on the high and low side fittings, and hooked up my gauges. No pressure ... atmosphere.

First thing I wanted to do was to pull a vacuum on it for obvious reasons and to see if it would hold a vacuum. I pulled vacuum on the high side and noticed that if I run the vacuum pump for even like 5 seconds and shut it off, I can hear a vacuum leak at or very close to the compressor. I can hear it sucking air for about 3 or 4 seconds after I shut off the pump. It's a huge leak so no chance for charging the system. So large in fact that any freon charged into the system would be gone before I could unhook my gauges.

My question is, should I just go ahead and get another compressor from someone on here, replace the current compressor as well as the seals at the compressor and try again (to pull vacuum)? Or do you guys know of maybe a smarter way to locate this leak. There's a lot of stuff down where this hiss is coming from, making it basically impossible to identify ... seems to me that pulling the compressor is in order, but wanted to gather some feedback before tackling that job.

Thanks.

JyRO

 

You need to find the leak. I would use a micro-leak detector and pressurize the system with dry nitrogen.

However, since it has been exposed to the atmosphere, you need to put in a new receiver/dryer once you find the source of the leak. Under General Principle, I would also replace ALL O-rings that are easily accessible.

Also, instead of converting to R134a, use Envirosafe Industrial 12, especially for the heat and humidity of Alabama:
http://www.es-refrigerants.com/produ...rant&Trying=ON

Good discussion here:
https://www.rx7club.com/showthread.p...ght=envirosafe

Micro-leak detector:
http://www.refrig.com/Product/Leak_D...n_Blu/bob.html

:-) neil

 

I went to a A/C shop and bought a o- ring kit and a quart of mineral oil. I took ever fitting apart and put in new o rings with some oil on them. I then poured about 4 oz of oil into my compressor (A/C shop told me to do this). Drove to a A/C shop, they refilled it and and i took it for a drive witha thermometer in the vent. I was getting 34 degrees out of it. That was 4 years ago and it is still working. Total cost was about 40.00 for parts and 110.00 for all the freon. Good luck

I would bet the o-rings for the large fittings on your compressor have failed.

 

never pull a vacuum to test for leaks. that will just draw moisture from the air into the system. pressurise the system with nitrogen. then use a water/soap mixture (you can just use some dishwashing detergant mixed with water 50/50) and spray on all fittings til you find the leak. new dryer is required as the system has been open for quite some time in a big way.

 

It's common to pull a vacuum and watch the vacuum and see if vacuum is lost to determine if there is a leak. That's how shop's do it, that's how it's done on an assembly line. For as long as I've owned this car and it's had this big of a leak, it's got about as much moisture in the system from this leak over time as is possible ... pulling a vacuum on it at this point won't effect anything. I bought a dryer some time back because I figured it would need a new one when I got to this point.

I like the idea of the micro-leak detector ... I'll check that out.

 

The A/C micro-leak detector works so much better than just soapy water, and detects both large and small leaks.

Check it out:
http://www.refrig.com/Product/Leak_D...lu/bigblu.html

ONE OF A KIND
BIG BLU needs very little introduction since it is used by nearly 80% of all HVAC/R Technicians throughout the U.S. and Canada.

Bubble leak detection was once considered gross and unreliable. To a certain degree it was true because the dominant makers of leak detector solutions relied on simple mixtures of soap and water.

BIG BLU is a strong and persistent film forming liquid that has excelled in the field identification of gas leaks. It remains, the only bubble/foam indicator capable of detecting micro gas leakage down to 0.65 ounces per year.
k_Detectors/Big_Blu/Leaklarge1.jpg

 

BTW: If you order some of their A/C micro-leak products, order "blue" Nylog to use on any fittings and as an O-Ring, Thread, and gasket sealant:

http://www.refrig.com/Product/Sealan...ylog_blue.html

http://www.youtube.com/watch?v=vAULfI8-Wwk

 

Mineral oil is incorrect for these cars. It may work, but it isn't what Denso intended. Denso chose to use a special synthetic oil "ND-7" for R-12 and "ND-9" for R-134a. This oil is unique to the TV series compressors.

 

Yes very important!

If you did not flush out the current oil, then you must use the SAME oil as currently in the system.

The nice thing with the Envirosafe Industrial 12, is that it can be used with ANY oil.

:-) neil

 

Ok...first of all why'd you put R-134a adapters on? R-12 is about $20 a can, and you need two cans. R-134a is $10 a can and you'll need 2 cans. R-12 will perform WAAAAAY better, and to properly convert to R-134a it will cost a whole lot more than the extra $20 you'll spend on refrigerant.

If it were mine, I'd do the following...blow a can of R-134a in there (don't run the compressor with it in there, however!), and see if you can't feel/see the leak....if not, spray on some soapy water. Shouldn't be too hard to locate since it is HUGE. A "micro-leak" detector isn't necessary if you can HEAR it.

What system do you have? Nippondenso or MANA? If you're MANA, read this:

https://www.rx7club.com/showthread.php?p=10092932

As for Envirosafe, flammability nonwithstanding, I've heard reports that it doesn't return oil to the compressor like it should, and some people just can't get it to cool like it should.

 

I put the 134 adapters on it ONLY because my manifold gauges do not connect to R12 connectors. I have no plan to convert it. My plan at this time is to find the leak and fix it. Replace the accumulator, determine what to do about oil (do that), vacuum the system and probably run some 134 in it initially to see how the system works. If it works but doesn't cool all that well, I'll vacuum it again and recharge it with the envirosafe R12.

I don't know which compressor it is, but its a somewhat early built '93, built in '92.

It makes sense to me to go ahead and get another compressor (from the classisieds here) and replace the compressor. Because I cannot effectively see ANYTHING down where I hear this leak, and if I replace the compressor, I can replace the seals along with it ... that should address this leak without the wild goose chase (since I can't see anything down there).

 

^ The only problem with that is if an a/c line is bad in which case changing the seals wont help. I would find the leak before buying a used compressor. That makes more sence to me.

Jack the car up,pressureize the system and spray with a soapy mixture on the compressor maybe then you could see the leak from underneath.


John

 

I don't know that ND-7 oil (the factory oil) is miscible with R-134a. You're liable to kill your compressor running it with R-134a. It is fine to blow some R-134a in to check for leaks, but you shouldn't run it with R-134a in the system unless you've put the proper oil in.

Any compressor from a 3rd gen that came from the factory with R-12 should work. The R-134a compressors had connectors which required slightly different o-rings versus the R-12 cars, so presumably the two are not interchangeable. As far as I can tell, only 1995 cars had R-134a.

If it were me, I'd pull the two hoses from the compressor, inspect them, replace all the underhood o-rings and then see if that fixed the leak.

If you get a bad used compressor then your goose-chase continues, or worsens if the compressor dies and craps metal all over the inside of the system.

 

That IS good reasoning. But yesterday while out in the EZ bake oven (my garage) while doing an oil change (car on 4 jack stands) I tried to see where these hoses attached to the compressor from every angle imagineable.

I couldn't see in that area at all. Would you guys recommend pulling the power steering pump to get at the attachment bolts? I've got the arms of a middle linebacker, so they don't Ed zachery slide into small areas.

JyRO

 

The suction line attaches at the front of the compressor, just behind the clutch. Should be easily visible from the front of the car with the battery out of the way. The discharge line...yeah...more or less impossible to see. Attaches to the top of the compressor at the very back of the unit.

I'm facing the same possible dilemma as you...may need to swap my compressor...leaking shaft seal. I had some more oil put in the system and it re-charged to see if the shaft seal wouldn't re-lube and quit leaking before I swap it, tho. I, personally, am leaning towards pulling the P/S pump so I can make dang sure I've got the discharge line on there correctly, and I don't get dirt inside the compressor/lines when swapping it out. Otherwise it has to be done by feel.

 

Yeah, I like to see what I'm doing and be sure it gets done correctly. With the trouble I have reaching into small areas, i'd probably want to remove the p/s pump. And if I'm going to go that far I might as well pull the compressor. No problem with the idea of checking for leaks, but I have a feeling that this leak is so bad that I wouldn't get but just seconds to trace the leak once injected refrigerant.

That leaves me with just pulling the pump, replacing it unless I find very obvious seal problems when I'm pulling the pump out. That would nice. Replace the seals, leave the pump, vacuum (check for leak down) charge and check operation.

Of course I could inject a can of cheap refrigerant with dye and almost immediately be able to see the dye if I have moved the p/s pump, hmmmm. That sounds like the best idea yet.

JyRO

 

You have to use refrigerant compatible with your exisiting oil. Envirosafe Industrial 12 is compatible with your oil, and since you're going to go with it in the end, then just get two or four extra cans . . .

If you remove the stock intercooler and undertray you should have good access to most of the lines for an inspection.

:-) neil

 

a few companies have UV sensitive fluid. so you can find a leak.

 

Neil, thanks for the info. However, considering how fast the refreigerant will blow through and out of the system, don't you think el cheapo off the autozone shelf refrigerant with dye is the way to go? It's not like this refrigerant will even get compressed, it just going to blow through just about as fast as I put it in. I don't want to be buying the more expensive envirosafe stuff just to blow it through.

 

Leak checking with flammable gases just seems like a bad idea anyways...although I suppose it could make it quite easy to find the leak...just light it on fire, then look for the spot where flames are shooting out of the system!

 

BUMP

Check the relief valve on the back of the compressor on the bottom. Use a 16mm wrench or socket. FYI, It is not availble through mazda anymore.


John