Knut, The best way to set your charge with R12 is sixty 60# of REST pressure. That is engine off and high/low pressures equalized. Rob Grady, P.J.Grady Inc. _____ From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of ksgrimsr Sent: Friday, May 30, 2008 11:00 AM To: dmcnews@xxxxxxxxxxxxxxx Subject: Re: [DML] Optimal R134a AC pressures While the number of pounds of refrigerant might be handy when first charging an empty system, it is not actually useful in my case where I'm servicing an existing system that is partially (mostly) charged. Does anyone actually have optimal pressure values rather than rule of thumb refrigerant amounts? I guess my next step would be to run a sweep of pressures and measure cooling performance to ensure I hit the sweetest spot, but that's a pain. Knut --- In HYPERLINK "mailto:dmcnews%40yahoogroups.com"dmcnews@xxxxxxxxxxxxxxxx, Farrar <fhudkins@..-.> wrote: > > My instructions say 85% of the original recommended R-12 charge. (e.g. 2 > pounds R-12 would mean no more than 1.7 pounds R-134a) However, I have > seen recommendations for 80% or 90%. > > Farrar Hudkins > #2613 (auto) > > ksgrimsr wrote: > > > > > > I serviced my R134a AC setup this weekend and it is performing well. I > > used the pressure tables in the service manual to set it up. > > > > Obviously, the pressure tables in the workshop manual are for R12. > > Does anyone have the pressuve values for optimal R134a performance? I > > want to make sure my system is running as efficiently as possible. > > > > Knut > No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.24.4/1474 - Release Date: 5/30/2008 7:44 AM No virus found in this outgoing message. Checked by AVG. Version: 7.5.524 / Virus Database: 269.24.4/1474 - Release Date: 5/30/2008 7:44 AM [Non-text portions of this message have been removed] ------------------------------------ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/