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Need help...Dry Ice and Alcohol Method of Evacuation didn't work

uunfews on Tue October 20, 2009 11:44 PM User is offline

Year: 2001
Make: Honda
Model: Civic
Engine Size: 1.7L
Refrigerant Type: r134a
Ambient Temp: 72
Pressure Low: 57
Pressure High: 60
Country of Origin: United States

Help, I tried to evacuate my system using a mixture of dry ice and 91% concentration isopropyl alcohol but it didn't
remove the freon 100% completely. There is still pressure in my system. My system has approx 18 oz per Honda manual but I was able to recover approx 9-10 oz only. I read of this method on here and and those people seemed successful in 100% recovery of the freon in their system. However, I didn't seem to have the same success.

At first the freon flow slowly from the low side to my 15oz can and stopped decreasing the pressure showing on the gauge after reaching approx 55 psi no matter how much more dry ice I added to the slurry. I recorded the dryice mixture to -50+F after which the digital thermometer errored out since it lower limit is -40 F. This indicates a negative vacuum in my recovery tank of -14 of HG per the temp/pressure relationship chart for r134a. I originally had the low side hooked up to my car and the yellow hose to my recovery tank. Then I barely cracked open the low side valve and the recovery tank valve since I was only interested in collecting the r134a and to minimize removing the oil as much as possible. After seeing no further increase in weight of the recovery tank I opened the low side valve wide open but it didn't make any difference. Finally in desperation I decided to hook up the gauge's hi side to the car and swap into place another completely emptied 15oz recovery tank in hope that by giving it some room I might be able to recover it better but it didn't collect one single gram of freon.


The static gauge now indicate 57psi low side, 60psi hi side at 67 relative humidity and 72 Fahrenheit degree. This indicates I still
have some freon remaining in the system.

What am I doing wrong? How do I remove the rest of the freon so that I get 0 PSI reading from my gauge?

Thanks.


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Newbie wanting to learn how to fix his 01 Civic AC in this freaking hot Dallas TX area.

mk378 on Wed October 21, 2009 12:11 AM User is offline

Did you pump the air out of the recovery tank before you started? Air does not condense, so the pressure will not drop as expected, and you will end up with a useless mixture of air and refrigerant.

Filling a recovery tank more than 80% full is dangerous. If you have a container completely full of liquid refrigerant with no head space, it will burst when the temperature increases.

The EPA only requires -4 inches vacuum to consider recovery complete. Even with a recovery machine, it is never possible to remove and reuse all the refrigerant. It is always going to be necessary to add some new on the recharge.

uunfews on Thu October 22, 2009 12:39 AM User is offline

Quote
Originally posted by: mk378
Did you pump the air out of the recovery tank before you started? Air does not condense, so the pressure will not drop as expected, and you will end up with a useless mixture of air and refrigerant.

Hi MK,

Yes I pulled a complete vacuum on the tank with the gauge connected till it reached -28 to -29" HG prior to connecting it to the car. I also freezed the second recovery tank unlike the first tank.


Quote
Filling a recovery tank more than 80% full is dangerous. If you have a container completely full of liquid refrigerant with no head space, it will burst when the temperature increases.

I had originally planned on doing this but keeping the tank completely inside the dryice/alcohol mixture so as to control the gas expansion till I am ready to put it back into the car. But as you know I didn't get that far...only got 10 oz inside the 15 oz recovery tank.

Quote
The EPA only requires -4 inches vacuum to consider recovery complete. Even with a recovery machine, it is never possible to remove and reuse all the refrigerant. It is always going to be necessary to add some new on the recharge.

I don't quite understand this statement. I would think that with a -4" vacuum that would mean practically nothing left inside the system.
Since I have a 57psi on low/60psi on hi side as indicated on the manifold gauge instead of the -4 inches of vacuum per EPA then how much do I have remaining inside my system???
How much can I realistically expect to recover then??? How much pressure is usually left if using a professional recovery machine if as you said it is never possible to remove all freon? I really really like to get as much recover as possible to see if my system was ever overcharged???



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Newbie wanting to learn how to fix his 01 Civic AC in this freaking hot Dallas TX area.

iceman2555 on Thu October 22, 2009 8:36 PM User is offlineView users profile

Seems we are being bombarded with asinine post the last few days.
First one will never be able to recover refrigerant with this method to insure '0' pressures. There will always be residual refrigerants encapsulated in the lubricants. This takes heat and time to allow for 'boil off' and then farther evacuation. It seems more time and money is being spend on this ridiculous method of recovery. Why not simply take the vehicle to a local shop and have them recover the refrigerant....pay the price and be done with the darn thing. One should not reuse refrigerant from this recovery procedure...it should be recovered and processed (reclaimed) thru a suitable recovery machine to remove residual lubricants, acids and other possible contaminates. That is why these required recovery/reclaim/recharge machines cost as they do....they perform a specific purpose in the AC repair process.
New standards for R/R machines require a removal of 95% of the refrigerant from a vehicle and must recharge to 1/2 oz of charge rate. There is no way in heck that this procedure, dry ice and 'what ever' will accomplish this removal....and farther more there is no way in heck that recharging with cans (12 oz or 30 lb) will match the require recharge necessary to adequately recharge a vehicle after a repair.
Legally the standards for recovery are so strict that the 'dry ice' thing will not work...and if that means 'X' # of oz are going to be 'blown off'....why waste the time and expense to salvage the rest....the procedure is left to your imagination. Heck,park the darn thing in the garage over nite and maybe the 'Freon Fairys' will come suck the stuff out. Recharging with the un reclaimed refrigerant may seem cost wise...but could actually re introduce contaminates back into the system. Can not in my wildest imagination consider the use of 'un reclaimed' 134a in a repaired system when the stuff is so inexpensive.
Suggest to contact a known good AC service center in your area...have them recover and then have them evac and recharge (use the correct equipment) the vehicle after your repair is completed.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

uunfews on Fri October 23, 2009 11:28 PM User is offline

Hey Iceman

I appreciate the comments and the help but didn't appreciate the sarcasm.

I read of this procedure on here from professionals like MK , Cussboy, George Bray, GM Tech, etc... and they reported good success rate of removal with the procedure hence why I come here hoping to enlighten myself on what I did wrong and to correct it. Nothing wrong with wanting to learn more is there???

I just feel that 50-60% of recovery is lower than those before me that use this method. Hence I want to check in with this forum where I feel exists for the purpose of helping poor DIYer like myself solve his own problem.

Peace!

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Newbie wanting to learn how to fix his 01 Civic AC in this freaking hot Dallas TX area.

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