Author Topic: R-152 A/C refrigerant conversion - Canned air  (Read 1499 times)

twincharger

  • Bad ass
  • *****
  • Posts: 1592
  • Bite me!
    • View Profile
R-152 A/C refrigerant conversion - Canned air
« on: March 27, 2016, 10:27:16 PM »

...So I had to replace the A/C compressor in my MR2 last summer.

The A/C worked in the car for a while, then quit.

No leaks, the system was fully pressurized with R134, the compressor clutch engaged, the compressor spun, but developed no pressure.

So I blew off a full charge of refrigerant because I, like most backyard mechanics don't have a refrigerant recovery system.

I replaced all the O-rings in the system, bought a new compressor and accumulator/drier.

I have a vacuum pump sourced from an old refrigerator and I borrowed a set of gauges from my brother.

I was looking for more refrigerant and ran across a post where someone used canned air in their car.

I did some research, found that canned air uses R152, looked up the temp/pressure chart and it looks good - quite similar to the R-12 that my car was designed for. 

I looked up the MSDS sheet and there are hazards, so don't drink it, don't inhale it and don't set it on fire.  How dangerous is it really when the proper use of the product is to spray it into the atmosphere onto live electronic devices?

With R152, the compressor pressure can be lower, less drag on the engine, less wear on the compressor, while giving colder air than R134.

The only drawback is that you must use ester oil instead of the PAG oil that is used with R134.

That wasn't a problem for me because my system was empty, so I pumped all the PAG oil out of my new compressor, and put the recommended quantity of ester oil in it.

I think I used one little bottle in the compressor and then one in the drier. I could be wrong, it was almost a year ago.

You can look up the oil quantity needed the same places that tell you how much refrigerant to use.

I blew out my lines with compressed air and installed the compressor and drier.

I evacuated the system and found no leaks, so I bought a can tap that punctures the side of a can instead of screwing onto the top.

The first can I tried to add did not go in so well.

When I punctured the can, it kind of dented it at the puncture site, so it was leaking pretty bad as I was filling.

The second can worked much better because I punctured it about 1/2 inch from the bottom of the can where there is more strength and it won't dent as easily.  The third can went in just fine.



So the low side temp is equivalent to about 30 degrees, and the high side is easily within the range that the compressor can handle, and lower than it would be with R134.

Here's an excerpt from www.aircondition.com,,

What should the high side pressure be?

With R12 systems, high side pressure is usually 1.8 to 2.1 times ambient temperature. That means on an 80 degree day, with moderate humidity, we would expect to see between 144 to 168 PSI on the high side. On hot humid days (with R12), you could say ambient temperature plus 100 PSI., and be pretty close.

With R134a it's common to see high side pressure between 2.2 and 2.5 times ambient temperature. On that same 80 degree day we would see between 176 and 200 PSI on the high side of an R134a system. The system operates in a specific range based on outside ambient temperature. High side pressure has a broad range relative to temperature because of heat load on the evaporator, humudity, airflow across the condenser, and engine speed.

So, the system pressures are normal, how well does it work?



Really well !!

So, I did this last year and then drove to JCCS in comfort, and it is still working fine this year with no trouble at all.

Here's a link with more info...

http://www.sae.org/altrefrigerant/presentations/presw-hill.pdf

So...  If your A/C isn't working, you can use canned air as refrigerant.

Make sure you change the drier, pump the old oil out of your compressor and evacuate the system first.

This information is presented for educational and entertainment purposes only, use at your own risk. :)

SidewaysEightSix

  • Bad ass
  • *****
  • Posts: 1787
  • It makes sense if you don't think about it....
    • View Profile
Re: R-152 A/C refrigerant conversion - Canned air
« Reply #1 on: March 28, 2016, 07:15:16 PM »
I'm curious to read into this some when I get home.


These are critical charged systems so a few oz's under or over can have negative effects in performance.   

Also these are vane style compressors, unlike HVAC receps, or scrolls.   These have more moving parts that need lubricated.  I don't see the oil change having a negative effect tho.

Two things to keep in mind regarding pressures.   1. The compressor is cooled by refrigerant.  If your pressures are lower, you are moving less refrigerant, and in theory you could end up with MORE drag on the compressor as the temps rise. 2.  Your system is designed with a particular superheat in mind. 
So by changing your pressures, you are also changing your superheat and sub cooling effectively changing your coil splits and effecting your efficiency (for better or worse)

I don't deal with 152 normally, but, due to the identity number of the refrigerant, I'm sure it's a blend.    If it's not a true azeotrope then you MUST charge as a liquid, not a vapor, and not at saturation.   Otherwise there is no way to know what you just changed the blend to.

Lastly, moisture and molecules that make our air, are all bad for your system when operating(especially OXYGEN!!!  oxygen+heat+compression = boom!  + flammables?   Yikes) Now I know those cans contain refrigerant, but are they purely refrigerant?  Could be, just never really dug into canned air.

Interesting for sure, glad it seems to be working well.   Most all drop in refrigerants will only see 70-90% efficiency compared to original refrigerants, and it gets worse at a fast rate once ambient temps reach 95+.   That being said, 152 isn't a drop in per say.

PS.   If you dudes ever need R134a, I use it everyday as it's widely used in low temp kitchen equipment.  It's CHEAP for contractors.  I can't get you a full jug (actually I can if you pay up front and give me a day or two) but I can just happen to loose a pound or 3 ;)

PSS.  This is also aggravating to me that I can't dump 10 oz of R134a on a system that I need to open up because by EPA regulation I have to recover 90% of the charge, yet companies can mass produce a product that disperses refrigerant into the ozone.   Sigh

« Last Edit: March 28, 2016, 07:48:43 PM by SidewaysEightSix »
"I'm fat and he's Asian.  Crazy food is bound to come up in conversation."
      "wait, am I the Asian?!"
"yeah bro.  Yeah, I think so."
      "I'm white!"
"visually, yes.  But so is Takumi Fujiwara."

Yes....  You are an expert

twincharger

  • Bad ass
  • *****
  • Posts: 1592
  • Bite me!
    • View Profile
Re: R-152 A/C refrigerant conversion - Canned air
« Reply #2 on: March 29, 2016, 10:58:04 AM »
I was hoping we would hear from an expert...  :)

From the MSDS sheet...
Difluoroethane (R 152a)
Chemical formula C2H4F2

Does not look like a blend.
If it was a blend and you used the whole can, then the proper ratio should be in the system, correct?
The lighter molecules would go in first, but once they are all in, the ratio should be theoretically restored.

From what I see printed on the can, it is 100% refrigerant.  They want it all to evaporate after you spray your keyboard.  No residue.

R152 is not exactly the same as R12, but it is closer than R134 according to the SAE paper.  Also cheaper and better for the environment.

I'm not too worried about efficiency, I'm sure my car's A/C system was made to work in a variety of conditions, pressures, altitudes, airflows and ambient temperatures.

Stay cool...

SDSK

  • Bad ass
  • *****
  • Posts: 1250
  • second time "couchi" owner
    • View Profile
Re: R-152 A/C refrigerant conversion - Canned air
« Reply #3 on: March 29, 2016, 12:16:10 PM »
so then this is a replacement for r134/r12 or a conversion to use the r152?

seems like a conversion and 30 degree cold air sounds fantastic!

SidewaysEightSix

  • Bad ass
  • *****
  • Posts: 1787
  • It makes sense if you don't think about it....
    • View Profile
Re: R-152 A/C refrigerant conversion - Canned air
« Reply #4 on: March 29, 2016, 01:40:29 PM »
^ 30 degree coil.   So around 40 degrees.


Yeah.  Most all refrigerants are HFC or CHFC. In theory, IF you got the whole container in there, than yes, the blend would be restored.   However, you never will get 100% unless you pull a vacuum on the suction side.   Will it be terribly far off?  Hard to say, likely it won't.   But let's say you use 1.5 cans...   Now you could be.     The fact that it's a 3 digit code starting with 1 hints it's a blend.   For reference, R134a is a blend of R12 and R22.  0+1=1  1+2=3 2+2=4.  134.   I've yet to really read into 152 to see what it is.   I do have a cool new set of high tech gauges that come with a tablet and software.   I need practice with it anyway, I can try and demo up your system and see what kinda effects we are looking at.

Obviously it's working for you.   Just an interesting read
"I'm fat and he's Asian.  Crazy food is bound to come up in conversation."
      "wait, am I the Asian?!"
"yeah bro.  Yeah, I think so."
      "I'm white!"
"visually, yes.  But so is Takumi Fujiwara."

Yes....  You are an expert