STILL More A/C questions

[dpuckett]

Ok, we have had a rush of AC questions lately- I would imagine in response to the softening of the American populace, and the heat that we can no longer endure like we used to (myself included- I have gotten spoiled by even 60deg AC duct temps). Anyway, after some research, I have about decided to recharge my system with HC12a (Propane, marketed under the name Duracool, and others). My question is, what is the TARGET pressure for the suction line when recharging the system? The websites I was at recommended checking the FSM, but said the average was 28-45psig. After a quick peruse through the AC section in my FSM, there was no range or target, just the temperature performance chart which said 25psi @100deg ambient temp (most shops are at least that here this week, even with the fans going). I think I also read not to exceed 50psi.



Daniel

 

[Greenleaf]

The low side will varry on the ambient temp as you know. I use a low side gauge that also serves to charge the system. It reads the low side pressure all the while it's connected. Take your reading with the compressor operating (engaged) and a fan blowing air into the condensor.



The proper charge will be about 14/15 oz of HC12a. I have dumped in much more than that and it will not cool properly. Floods the evap. you know



You will see 29/39 psi whe all is well. When you order the stuff you'll recieve a few pages of Q&A along with some instructions and other info you didn't know you wanted to learn.

 

[rlyons]

I hope that is freon and not propane! I would not want propane in my system.

 

[Greenleaf]

I hope that is freon and not propane! I would not want propane in my system.

You need to spend some time and educate yourself on the use of HCR12a. You will be (very) happy that you did, along with setting on a fatter wallet



-S

 

[Steve Graham]

I would strongly advise you not to use any hydrocarbon refrigerants. Here a warning from MACS (Mobile Air Conditioning Society) about the dangers of such use.



If you AC system is not working very well, it's best to fix it (correctly) and not relay on a quick fix or magic bullet.



Steve

 

[dpuckett]

I read the link, and while I have not dug up the EPA requirements, it appears to me to be a sales pitch to use their products and 134A retorfits as opposed to HC12 or HC134a, along with blindly obeying what the Egotistical Pinhead Admin wants (control). I remember reading somewhere recently that the 134a actually has a lower flash point than HC12 (more flammable). I have read conflicting reports of whether or not 134a and 12 are flammable or not. Anything will burn if you get it hot enough.



Point is, I appreciate you trying to watch out for us, but that was not the purpose of this thread, and we have gotten off topic. I am not impressed with the performance of the 134 in my system, and will have it evacuated by a trained and certified technician prior to installing the HC12.



-DP

 

[rlyons]

Well all I can say is, it is your choice but I am certified in automotive A/C and there is no way I will put an explosive gas in my a/c system. What happens in an accident? If a line is punctured and the gas excapes? Look at the MSDS sheets for HRC-12A. The gas is explosive when it collects and also will flash back to an ignition source. I have worked enough accidents in my years running a wrecker service and in the local Fire Dept to know there are many ignition sources on an accident scene. I will not put myself, my family and others at risk for the sake of saving a little money. After doing my research on this I know for a fact now I won't be using it.

 

[Steve Graham]

Point is, I appreciate you trying to watch out for us, but that was not the purpose of this thread, and we have gotten off topic. I am not impressed with the performance of the 134 in my system, and will have it evacuated by a trained and certified technician prior to installing the HC12.

-DP

Fair enough.

But at to the hazards, R12 when ignited gives of phosgene gas, a deadly poison. I'm not sure what happens to r-134a. As for the performance of a retro fit from r12 to r134, done correctely, will work as good if not better that r12. The bigest expence is replaceing the condencer with one that is 20% larger.



Steve

 

[Greenleaf]

I also read the link and it's full of half truths like a politician running for office. . It's clear that it's a commercial. Like I said it would be best to educate one's self on the use of HC12a as well as the complete line of HC refrigerents used in many, everyday applications, then decide for yourself if it's something you as an individual would like to pursue.



I don't care one way or another if people use it. I don't manufacture it/sell it.



-S

 

[dpuckett]

... . As for the performance of a retro fit from r12 to r134, done correctely, will work as good if not better that r12. The bigest expence is replaceing the condencer with one that is 20% larger.

Ok, so that is nice to know, and might explain why I haventy had any luck with the 134a conversion- I kept the stock condensor.



-DP

 

[Steve Graham]

Ok, so that is nice to know, and might explain why I haventy had any luck with the 134a conversion- I kept the stock condensor.



-DP

The other item that needs to be changed is the expansion valve or Orifice Tube, depending on which one your system has. Then there's flushing, changing out the "O" rings, the details make a difference.



I just finished a install of a custom r-134 ac system in my Scout, it blows 40 F with a 95 F ambient tempature.



Steve

 

[TKingsbury]

Like I've said before, I have 40deg air out of my ducts using 134a, and that was last week when it was well over 100 deg outsdie. No changing of any major components. I would however recommend changing the expansion valve as well as the drier. I kinda regret not changing my exp valve, it sometimes seems to stick open, so my low side goes up and my high side goes down and it doesn't cool very well. But, overall I am pleased with the cooling my a/c provides. As to the condenser needing to be 20% larger, I believe it only needs be more efficient, not necessarily larger. Alot of r12 vehicles have condensers that are larger than necessary, so a change to 134a is not a biggie. The condenser in our trucks looks to be fairly efficient compared to older models. These are my thoughts from my experiences, take them for what they're worth. Hell, I don't really care what anyone uses as long as it makes cold air in their vehicle. My . 02

Travis. .