[GMCnet] R134a conversion [message #258071] |
Thu, 07 August 2014 13:54 |
emerystora
Messages: 4442 Registered: January 2004
Karma: 13
|
Senior Member |
|
|
Let me start out by saying I don't recommend doing this. Systems that were engineered for R12 traditionally do not perform well with R134. In some cases, it works but most of the time the condenser is too small, the fan is insufficient and an already tired compressor usually quits under the extra load. Some of the other problems is that when R134 is introduced to mineral oil (R12 oil) it turns to jello. This can happen in a place where not much is effected or it can cause a real problem. R134 is also made of smaller particles and can find a smaller leak.
Having said all that, here's your concerns and procedures. First you have to remove as much of the old oils as possible. That usually means removing compressors and flushing condensers and other components. An additional condenser fan will improve things. You need to charge the system with preferably "ester" oil which is compatable with both R12 and R134. Charge the system with about 75% of the original capacity of refrigerant and hope for the best. In other words if you had 3.5 pounds of R12 you would use 2.6 pounds of R134a. If you use 3.5 pounds you will be say overfilled
The R134a will give you about 10% less cooling than the R12.
I really suggest that you dump the R 134a and fill with three 6 oz. cans of Duracool (HC 12a). You'll have about 20% better cooling than the R134a and it will be compatible with whatever oil is in the system.
Your compressor high side pressure will be about 100psi or more lower. This will give less load on the engine and less wear on the system. It also will be less prone to leaking past the clutch seal as the molecule size is much larger than R12 or R134a.
Emery Stira
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
Re: [GMCnet] R134a conversion [message #258076 is a reply to message #258071] |
Thu, 07 August 2014 14:46 |
mickey szilagyi
Messages: 273 Registered: January 2013
Karma: 0
|
Senior Member |
|
|
Emery, and everyone else too.
As in another post we don't know what system we have, R12 or 134A. We will check to see what ports we have. But since Duracool can go into either system can't we just put three cans of Duracool in our system and see what happens? Can we get Duracool into an R12 port? Worst that could happen is it leaks out. What harm could trying this do?
Thanks!
Mickey
1977 Kingsley, 403, Lansing, MI
|
|
|
Re: [GMCnet] R134a conversion [message #258080 is a reply to message #258076] |
Thu, 07 August 2014 14:56 |
Keith V
Messages: 2337 Registered: March 2008 Location: Mounds View,MN
Karma: 0
|
Senior Member |
|
|
Emery you recommend ester oil.
What about PAG oil? I thought PAG was the one compatible with both R12 and 134.
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
|
|
|
Re: [GMCnet] R134a conversion [message #258082 is a reply to message #258076] |
Thu, 07 August 2014 14:52 |
Sammy Williams
Messages: 522 Registered: August 2010
Karma: -2
|
Senior Member |
|
|
Hello:
If you have a GMC Mortorhome, you have an R12 system. R134a wasn't mandated
for use until 1994, LONG AFTER the last GMC motorhome left the plant in
1978.
As for previous owners, if they converted the unit to r134a, the connectors
WILL BE different on the fittings. The R12 fittings and R134 fittings are
different.You can tell, just by looking.
Sammy WIlliams
1978 GMC (its in SC and im here...) lol
On Thu, Aug 7, 2014 at 2:47 PM, Mickey Szilagyi
wrote:
> Emery, and everyone else too.
>
> As in another post we don't know what system we have, R12 or 134A. We
> will check to see what ports we have. But since Duracool can go into either
> system can't we just put three cans of Duracool in our system and see what
> happens? Can we get Duracool into an R12 port? Worst that could happen is
> it leaks out. What harm could trying this do?
>
> Thanks!
>
>
> --
> Mickey
> 1977 Kingsley, 403, Lansing, MI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
Re: [GMCnet] R134a conversion [message #258083 is a reply to message #258076] |
Thu, 07 August 2014 15:11 |
Ken Burton
Messages: 10030 Registered: January 2004 Location: Hebron, Indiana
Karma: 10
|
Senior Member |
|
|
You can install Duracool into an R-12 port IF you have the right adapters. There is a technical legality when doing this. The best thing to do it install the R-134 fitting adapters on your r-12 fittings and charge it with standard R-134 hoses. The adapters are, or have been available, at Walmart and AutoZone for less than $10.00 .
If all of the existing refrigerant is gone then you need to pull a vacuum on the system and maybe replace the dryer depending on how long it has been empty of refrigerant. If you can not hold the vacuum then you need to go find and fix the item(s) that are leaking.
3 cans is a bit too much on a standard GMC. DO NOT over charge the system. I would use Emery's numbers of 20-22 PSI on the low side at 1500 RPM with the AC and fan set to maximum. That will probably happen at around 2.5+ cans
More refrigerant and higher pressure is NOT a good thing. The higher the pressure the warmer the AC will run. The reason we use the 20-22 number is that makes the refrigerant cool the evaporator at just above freezing (32F).
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
|
|
|
Re: [GMCnet] R134a conversion [message #258090 is a reply to message #258071] |
Thu, 07 August 2014 16:06 |
Bob de Kruyff
Messages: 4260 Registered: January 2004 Location: Chandler, AZ
Karma: 1
|
Senior Member |
|
|
emerystora wrote on Thu, 07 August 2014 12:54Let me start out by saying I don't recommend doing this. Systems that were engineered for R12 traditionally do not perform well with R134. In some cases, it works but most of the time the condenser is too small, the fan is insufficient and an already tired compressor usually quits under the extra load. Some of the other problems is that when R134 is introduced to mineral oil (R12 oil) it turns to jello. This can happen in a place where not much is effected or it can cause a real problem. R134 is also made of smaller particles and can find a smaller leak.
Having said all that, here's your concerns and procedures. First you have to remove as much of the old oils as possible. That usually means removing compressors and flushing condensers and other components. An additional condenser fan will improve things. You need to charge the system with preferably "ester" oil which is compatable with both R12 and R134. Charge the system with about 75% of the original capacity of refrigerant and hope for the best. In other words if you had 3.5 pounds of R12 you would use 2.6 pounds of R134a. If you use 3.5 pounds you will be say overfilled
The R134a will give you about 10% less cooling than the R12.
I really suggest that you dump the R 134a and fill with three 6 oz. cans of Duracool (HC 12a). You'll have about 20% better cooling than the R134a and it will be compatible with whatever oil is in the system.
Your compressor high side pressure will be about 100psi or more lower. This will give less load on the engine and less wear on the system. It also will be less prone to leaking past the clutch seal as the molecule size is much larger than R12 or R134a.
Emery Stira
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Emery--most of us spell your name wrong but I've never seen you misspell it yourself
Bob de Kruyff
78 Eleganza
Chandler, AZ
|
|
|
Re: [GMCnet] R134a conversion [message #258100 is a reply to message #258076] |
Thu, 07 August 2014 17:08 |
emerystora
Messages: 4442 Registered: January 2004
Karma: 13
|
Senior Member |
|
|
You can easily put Duracool (HC12a) into a R12 port. Other than the standard R12 gauges all you would need is a way to get it from the Duracool can to the R12 port. The can has a screw on fitting on the top that fits a R134a hose. I purchased a hose that had the can fitting on one end with a valve and an R12 fitting on the other end. There are also R12 hoses that clamp onto the side of any type of can and puncture the can.
I bought my adapter and my Duracool here:
http://www.bennettsupply.net/cart/
You can but the three can kit with the hose or just the hose alone. Be sure you get the R12 hose and not the R134a hose.
Emery Stora
77 Kingsley
Frederick, CO
On Aug 7, 2014, at 1:47 PM, Mickey Szilagyi wrote:
> Emery, and everyone else too.
>
> As in another post we don't know what system we have, R12 or 134A. We will check to see what ports we have. But since Duracool can go into either
> system can't we just put three cans of Duracool in our system and see what happens? Can we get Duracool into an R12 port? Worst that could happen is
> it leaks out. What harm could trying this do?
>
> Thanks!
>
>
> --
> Mickey
> 1977 Kingsley, 403, Lansing, MI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
|
|