I have been following this thread for some time... (since it started)


I have six immaculate RX-7's and have converted nearly all to R134. Yes it works. Yes it blows cold. If you play with the amount of R134 you have in the system you can get it blow pretty cold. Today I was working on a car I just acquired and found a blown A/C O-ring. I replaced it and pulled a vacuum on the system. Just for ***** and giggles... I put r152a in the system. I put in 10 oz . It blows ICE cold. Noticeably colder than any of my other conversions. I was impressed.

BUT here is the thing: You can tell the A/C compressor is working much easier. The engine idle fluctuates way way less when the A/C clutch engages and the compressor is much quieter. Tomorrow I am converting my daily driver RX-7. I'll post an update after my next road trip.

 

A couple of things to note here:

Check the temperature pressure charts at the front of the thread and you will find 152a is nearly identical to R12. This is lower than R134a at high temps encountered in hot weather, traffic and initial cool down. But in our cars (inadequate condenser!) 152a pressures are MUCH lower than 134a pressures of a fully-charged system. So we tend to not charge the 134a up all the way, not by design, but by charging to pressures. It just happens.

Here is why you notice the much colder temps: In your climate, you get adequate performance from what is essentially an undercharged 134a system.

Now that you have 152a, you are experiencing the system as it was meant to work.

Welcome to A/C that really works!

BTW the lower pressures translate to less Hp use for the compressor and better gas mileage.

152a works in 134a OEM systems too-lower pressures better mileage.

 

I completely agree about it running better and quieter, my old 1957 frigidaire fridge compressor has never been so quiet. I'm about to do my rx7 now, just tying to locate the right size bolts for my compressor!

 

how much 152 should you put into an fc

 

20-22oz of 152a for the FC. Think its on page 3 or 4 with directions.

 

Speaking of quantity, did you only put 10 oz total od 152a?

 

For the fc, 14-16oz will do.

I still get comments on how cold the AC is in my LS400, after the r152 conversion

 

Ok I have a question. I recently pulled my engine to clean something's up and want to make the ac come to life again. Is there anything I can do now that the engine is out to prepare when everything is hooked back up? Check the compressor or stuff like that?

 

any one?

 

Clean clean clean, the cleaner the system the longer and better it will preform. Clean the condenser, ducting for the rad, oil cooler, and condenser. Check hoses to nicks, clean inside of hoses. Change all the o-rings.

 

I always use brake cleaner in ALL the lines, condenser, and evaporator core. Load the line (or core) up with brake cleaner, then blow it out with compressed air into a rag. Repeat several times until every bit of gross comes out and it's coming out clear.

Do not do that for the compressor. Use oil. Fill it up with oil, crank it over a bunch of times, turn it over, and measure the amount of oil that comes out. Repeat until the oil comes out clean. I haven't looked at how much oil you're supposed to put in the system, but that's why you measure the amount going in and out, so the net amount going in is the correct amount of oil.

Replace the receiver dryer, but don't actually open it up or install it until the VERY end, when you are ready to seal the system and draw a vacuum on it.

 

ok i can take apart every line and clean them out with brake cleaner but how do i clean the condenser and evap? remove and clean them? and where do i find the right kind of oil for the compressor?

 

OK. I'm an idiot about HVAC. I don't know nuthin' 'bout it. So, please excuse my ignorance.
When it needs it, I will take my '91 vert to an auto shop that does A/C work and have them change my system over to R152a. (If it is legal in WI to do so.) Is it just a matter of flushing the existing system and replacing the R12a gas with R152a? Or are there mods to the mechanicals that need to be done as well?
I appreciate y'all sharing your knowledge with the rest of us. When I asked the service people at the dealers if they did conversions from R12a to R134 they looked at me like I was speaking in a foreign language. They had to ask around the shop to get an answer of "I guess we do--don't we?" After that I decided I'll take it to a specialist shop when the time comes. Meanwhile, the R12 has been blowing cold for at least 16 years and just keeps on goin'...

 

this r152 is interesting...

1. can you just reuse the current oil in the compressor(old r12/r134) if it was running fine before?

2. is r152 corrosive like r134, requiring you to change out all o-rings?

 

No matter what, I will always change o rings and flush everything I can when doing major AC work. To answer Nataku's question, you can leave it in the car or take it out. All you have to do is break the lines loose and shoot it full of brake cleaner, then blow it out. For the other questions, I recommebd reading page 2 again. It's all there.
If you're evacuating a system that worked fine, then I wouldn't do this. It's not broken, so don't fool with it and you'll be fine. If it stopped working, then find out what caused it to stop before heading any further. When compressors go bad (for instance) they spew gunk all inside the system, and that's gotta get cleaned out before proceeding.

 

Not to be a jerk,but every question on this page is answered in the first couple of pages of this thread. Please read it so you don't miss other important details. If you are asking these questions, you haven't read the answers in context. If you did read and missed the answers, please re-read.

Here to help, but not to repeat for the non-readers. Yes it's alot to read. Yes, cold a/c is worth it!

Good Luck!

Jack

 

Maybe it's worth updating the OP to cover most common questions that people keep asking over and over? Or perhaps add links to the later posts in the thread.

It's one thing to read a very long writeup on how to do something and absorb all of the details. It's another thing to read a short writeup followed by dozens of other people's conversations which may or may not have anything to do with the question your mind is asking.

jackhild59 is right that it's worth it. I charged my A/C with this method and it's been (almost) keeping up with the Florida heat all summer.

 

Completed my 10th? car with 152a today.. a 1990 Miata. maybe it's more like the 15th car i've done... i lost count after the first 4 rx7s...

total charge called for 16 oz, i used a 7 oz can and a 10 oz can, because left over 40 psi in the can, and lines that you loose.

Blew the ladies mind.... she was very happy.

 

after reading this(now) I have a couple of questions.

r12 oem drier is not made to tolerate synthetic oils....
? so which drier do you use thats non-oem? or do you mean get a new oem one that has not had r12 running through it?


If you have removed the compressor...
? I have not removed it. so I guess I have to inorder to get the mineral oil out? or is there another way to remove it with out taking the compressor off?

I really like the information you have posted about this. seems like the best/cheapest/logical "refrigerant" to use. I wish the write up was sticky'd and cleaned up of peoples posts. the real information doesnt start till half way through page 2. dont mean to be ungratefull...just saying it could be easier to read.

 

Okay I have read the first page and the rest of the thread a couple of times and I'm surprised no one has asked what to use to find leaks in our system? I know there is UV dye but doesn't the system need to be charged in order for it to work through the whole system? Also I have found small cans the come charged but they claim that they work in all systems?http://shop.advanceautoparts.com/wcs...1_pri_larg.jpg

 

I'll take this one jack. just sit back...

Firstly, these are my personal methods that i've taught myself in the absence of proper equipment($$$) and the need/want to not waste freon, by charging a leaking system with dye and freon, and waiting to find the leak, as was the normal method other techs use.

most scales are off once you get into vacuum on most gauges, the easiest thing to do is pull a vacuum on just your gauges well enough that it holds the same spot for 24 hours and doesn't drop when you turn the vacuum back on. then you know you're were the needle point is at, when you don't have a leak, this i will refer to as bottomed out.

pull a vacuum, if it doesn't reach the bottomed out, you obviously have a leak. now what..

well take some dye and introduce it into the system, either let the vacuum pull it in, or open it back up and pour it in.. just get some in.. most ester oil that you will buy today already has the dye in it..

Here's my specialty number 1.. add air. compressed air from a shop hose, that should have a drier built into the compressor. the ones we've had at shops would never have moisture in them. if not use an air/water separator like for a paint gun. this will force the dye out of the system, as you fill the thing up with 100-120 psi, DO NOT RUN the COMPRESSOR! then use a uv light to find the dye, and vacuum blah blah as normal.

Here"s my specialty number 2. if you think you have an evap core failure, the system makes a big circle, just disconnect the evap and cap both ends, pull a vacuum again without it in the circle. you can do the same for the rubber lines, the condensor, and even the compressor itself, i often test replacement(used) rubber hoses before installing them. i used vacuum nipples of the large kind and a pipe clamp, sometimes i can pull to vacuum without a clamp at all.

yous welcome.

 

You remove the OEM drier, buy a new one that's compatible with synthetic oils (hint: pretty much any that you can currently buy are compatible with all oils)
The problem is not the oils so much as the baggie that contains the desiccant in the drier. Synthetic oils will dissolve the baggie in the older type, and release the desiccant all through the system, hence the "your life will suck" warning. Driers are cheap. Just replace it for good measure regardless.

Not sure on this one. It would be best if you got as much oil out as possible, otherwise it just sits there taking up space that could be used for more refrigerant. I don't think it hurts anything, per se.

 

Going to be converting to r152a in the next few weeks. Just waiting on the last few parts to come in. Cross your fingers that my system doesn't have any leaks!

 

if you use the vacuum method and have a manifold gauge set you will know if you have any leaks during the vacuum hold test. take a reading after 15 mins of vacuum and close the system, watch the gauge for another 15 minutes and if it doesn't lose any vacuum then you should be golden.

sometimes the system only leaks under pressure though, which is a little more complicated to test. most people run the dye in the system and charge it then find the leaks with the dye light, sometimes this isn't as easy as it sounds. what i do is pressurize the system to 150psi and then use a soapy solution to find any possible leaks before charging the system, if it hold pressure at 150 for 15 minutes, then holds vacuum for 15 minutes there should be no reason to have any leaks.

 

The A/C hasn't worked in years on my 90 GXL. I have all the parts to rebuild the system including a new compressor, condenser and evaporator. I would like to also replace the hoses, but they are no longer available from Mazda. Can anybody recommend a source that will rebuild A/C lines?