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a/c pressures [message #303250]

Thu, 07 July 2016 20:10

Dan Gibb

Messages: 24
Registered: May 2015
Location: Tucson, Arizona

Karma: 0

Junior Member

this is the 3rd time I have tried to post this.......if any others show up I'm sorry.

I replaced the 134a in my A/C system with a Dura Cool clone called EnviroSafe. The 134a was working fine, but I was concerned with the high head pressures on our old systems. With the 134a I had a low side of 35lbs and a vent temp of 50 . My ambient temp is 105deg.

I put in 3 of the 6oz cans of the clone as per the instructions on http://gmcmotorhome.info/list.html#RAD, scroll up to Dura cool conversion. My low side went to 55lbs and temp to 71. I let out enough to bring pressure to 35 and the temp went to 60 , I let out more to 30 and the temp went to 66. I think the system was empty when I put it in, any way the gauge said 0.

Anyone know what the best pressures are to use? What am I doing wrong? I really don't want to take it all out and start over.....

Dan Gibb 1977 Eleganza II Tucson, Az

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Re: [GMCnet] a/c pressures [message #303251 is a reply to message #303250]

Thu, 07 July 2016 20:26

bdub

Messages: 1578
Registered: February 2004
Location: Central Texas

Karma: 5

Senior Member

Low side pressure 21 to 25psi @ 1500 rpm. Should take about 2.5 cans of
duracool.

On Thu, Jul 7, 2016 at 8:10 PM, Dan Gibb wrote:

> this is the 3rd time I have tried to post this.......if any others show up
> I'm sorry.
>
> I replaced the 134a in my A/C system with a Dura Cool clone called
> EnviroSafe. The 134a was working fine, but I was concerned with the high
> head
> pressures on our old systems. With the 134a I had a low side of 35lbs and
> a vent temp of 50 . My ambient temp is 105deg.
>
> I put in 3 of the 6oz cans of the clone as per the instructions on
> http://gmcmotorhome.info/list.html#RAD, scroll up to Dura cool
> conversion. My low
> side went to 55lbs and temp to 71. I let out enough to bring pressure to
> 35 and the temp went to 60 , I let out more to 30 and the temp went to 66. I
> think the system was empty when I put it in, any way the gauge said 0.
>
> Anyone know what the best pressures are to use? What am I doing wrong? I
> really don't want to take it all out and start over.....
>
> --
> Dan Gibb
> 1977 Eleganza II
> Tucson, Az
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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bdub
'76 Palm Beach/Central Texas
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Re: a/c pressures [message #303252 is a reply to message #303250]

Thu, 07 July 2016 20:32

Larry

Messages: 2875
Registered: January 2004
Location: Menomonie, WI

Karma: 10

Senior Member

Dan Gibb wrote on Thu, 07 July 2016 20:10

this is the 3rd time I have tried to post this.......if any others show up I'm sorry.

I replaced the 134a in my A/C system with a Dura Cool clone called EnviroSafe. The 134a was working fine, but I was concerned with the high head pressures on our old systems. With the 134a I had a low side of 35lbs and a vent temp of 50 . My ambient temp is 105deg.

I put in 3 of the 6oz cans of the clone as per the instructions on http://gmcmotorhome.info/list.html#RAD, scroll up to Dura cool conversion. My low side went to 55lbs and temp to 71. I let out enough to bring pressure to 35 and the temp went to 60 , I let out more to 30 and the temp went to 66. I think the system was empty when I put it in, any way the gauge said 0.

Anyone know what the best pressures are to use? What am I doing wrong? I really don't want to take it all out and start over.....

My system puts out best cold air between 20 and 25lbs low side. You have to much in there. Bleed more out. JWID

Larry

78 Royale w/500 Caddy
Menomonie, WI.

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Re: a/c pressures [message #303254 is a reply to message #303250]

Thu, 07 July 2016 21:06

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

It seems counterintuitive, but if the expansion valve is doing what it is supposed to, less pressure gets colder. The right undercharge will result in ice in the evaporator. So once the condensation in the evaporator starts to freeze, you would need to put more in it.

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