| [GMCnet] A/C head pressure [message #324943] |
Sat, 14 October 2017 13:43  |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Senior Member |
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Just changed out the clutch on the A6 and would like some input on high side head pressure. Currently using R-134 but I know lots of folks use Duracool. Questions are: what is an optimum high side head pressure for R134 and does using Duracool allow for a lower high side head pressure.
thanks
Gary Worobec
gtw5@earthlink.net
1973 23 GMC Glacier
Howell EFI/EBL
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| Re: [GMCnet] A/C head pressure [message #324948 is a reply to message #324943] |
Sat, 14 October 2017 18:20  |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Senior Member |
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Thanks Rob
> On Oct 14, 2017, at 3:01 PM, Rob Mueller wrote:
>
> Gary,
>
> Here's a link to the presentation Emery Stora made at a GMCMI convention, I GA-RON-TEE you will be sold on Duracool after reading
> it. The last few pages provide detailed instructions on how to fill the A/C system.
>
> http://www.gmcmi.com/wp-content/uploads/2017/04/Duracool-updated-Mar-2017.pdf
>
> Here's a link to the Dura Cool home page:
>
> http://www.duracool.com/
>
> Here's a link to the Frosty Cool home page:
>
> http://frostycool.com/
>
> I have run Dura Cool and Frosty Cool in Double Trouble and could not detect any difference in the performance of the dash a/c.
>
> I also have it in my 1995 Jeep Grand Cherokee and it works fine.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Gary Worobec
> Sent: Sunday, October 15, 2017 2:44 AM
> To: Gmclist
> Subject: [GMCnet] A/C head pressure
>
> Just changed out the clutch on the A6 and would like some input on high side head pressure. Currently using R-134 but I know lots of
> folks use Duracool. Questions are: what is an optimum high side head pressure for R134 and does using Duracool allow for a lower
> high side head pressure.
>
> thanks
>
>
> Gary Worobec
> gtw5@earthlink.net
> 1973 23 GMC Glacier
> Howell EFI/EBL
>
>
>
>
> _______________________________________________
> GMCnet mailing list
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> GMCnet mailing list
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Gary Worobec
gtw5@earthlink.net
1973 23 GMC Glacier
Howell EFI/EBL
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| Re: [GMCnet] A/C head pressure [message #324949 is a reply to message #324943] |
Sat, 14 October 2017 19:02 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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You can find lots of charts for R12 and 134a on line that work off temp/humidity. The rough rule of thumb is that 134a high side will go higher than R12 (134a can get above 300PSI ) and HC12 will be lower than R12 as a guideline.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] A/C head pressure [message #324951 is a reply to message #324943] |
Sat, 14 October 2017 19:41 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I seldom look at high side pressure on R-134 systems. There are too many variables for an accurate diagnosis in my opinion.
I got burned once by not looking at the high side presssure. My Colorado would start cycling more that normal when the outside temp went over 90 to 95. I eventually, after many trial and errors and several months, found that there was too much r-134 in the system and that the high side trigger point for the computer was 417 PSI. Removing just a Little R-134 took care of the problem. In the last 10 years on that same vehicle I have looked at the high side a couple of times and on a hot day pressure in the middle 300's appears to be normal.
I do not know if that helped or not.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] A/C head pressure [message #324954 is a reply to message #324943] |
Sat, 14 October 2017 21:02 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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The safest and easiest way to charge any system would be to weigh in the charge as per the mfg specs for the vehicle. On a warm day it generally is necessary to mist the condenser with a garden hose to keep head pressure in check while charging the system.
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Sat, 14 October 2017 21:03] Report message to a moderator |
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| Re: [GMCnet] A/C head pressure [message #324957 is a reply to message #324954] |
Sun, 15 October 2017 00:17 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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While that is the modern way to charge a system, I have worked on several vehicles that have needed to be tweeked after using the weight method. On my Colorado it was charged three times by weight using two different machines. It still ended up being over charged. I have worked on several new Hondas that were checked by dealers using the weight method only to have them freeze up from being undercharged. My Blazer was charged using weight and a machine only to end up slightly under charged. So charge by weight and be prepared to get out the gauges if it needs a little tweeking.
I charge a completely empty r-134 system using a 30 pound bottle and a set of scales. Usually that is close enough.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] A/C head pressure [message #324967 is a reply to message #324957] |
Sun, 15 October 2017 12:12 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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I can see that happening if the a/c had a wrong label on it. In my experience I never had a problem with the hundreds of package units I charged in the trade. However I only charged a few dozen vehicles in which I used a commercial charging cylinder to weigh in the charge, in each case they were a correct charge but as you and I know a good set of Gage's are also needed to conferm the results. A lot of times the mechanical engine fan doesn't 't move enough air at idle so the condenser needs a cooling mist if it is idled for very long,
Roy Keen
Minden,NV
76 X Glenbrook
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