Home » Public Forums » GMCnet » Stupid AC, 20psi, 120psi...73degrees
| Stupid AC, 20psi, 120psi...73degrees [message #137765] |
Sat, 06 August 2011 15:08  |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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Continuing from this thread;
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&th=18173&start=0&rid=1431
Or for the Email crowd subject is; More AC questions....
so I bought real (well harbor freight) AC gauges.
* Low side 19 psi
* High side 120 psi
* Recirc blocked for 100% recirc
* engine at 1500 rpm
* run for 20 minutes
* heater hose shut off mechanically
* ambient temp 78 degrees
AC outlet temp is 73 still degrees
Secondary evap temp was 63 degrees
(this one is definitely 100% recirc!)
What the heck?
Do I have air in the system??
Gremlins?
Trolls??
Keith, cant see the problem, vasilakes
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: Stupid AC, 20psi, 120psi...73degrees [message #137777 is a reply to message #137765] |
Sat, 06 August 2011 17:02  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Did you vacuum the system prior to charging it. If no then you mihgt have a mixture of refrigerants.
If I remember correctly you said it was dripping condensate (water). That tells me that it is cooling. If this is true then it is time to start looking at the air mixture door and door seals.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Stupid AC, 20psi, 120psi...73degrees [message #137784 is a reply to message #137777] |
Sat, 06 August 2011 18:25 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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Yep I pulled a vacuum with an AC compressor for a few hours.
Then charged it
The thing that bothers me the most is I have a second evaporator under the couch that is only reaching 63 degrees.
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: Stupid AC, 20psi, 120psi...73degrees [message #137785 is a reply to message #137784] |
Sat, 06 August 2011 18:38 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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| Quote: |
Continuing from this thread;
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&th=18173&start=0&rid=1431
Or for the Email crowd subject is; More AC questions....
so I bought real (well harbor freight) AC gauges.
* Low side 19 psi
* High side 120 psi
* Recirc blocked for 100% recirc
* engine at 1500 rpm
* run for 20 minutes
* heater hose shut off mechanically
* ambient temp 78 degrees
AC outlet temp is 73 still degrees
Secondary evap temp was 63 degrees
(this one is definitely 100% recirc!)
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If you are trying for 19psi I assume you are using Duracool. Since you have two expansion valves you are using more volume of refrigerant that a stock system. Perhaps the low side needs to be a little higher. Juice it to 25 and see what the difference is. You may find your system needs to run at a higher pressure.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: Stupid AC, 20psi, 120psi...73degrees [message #137787 is a reply to message #137784] |
Sat, 06 August 2011 19:09 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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| Keith V wrote on Sat, 06 August 2011 19:25 |
Yep I pulled a vacuum with an AC compressor for a few hours.
Then charged it
The thing that bothers me the most is I have a second evaporator under the couch that is only reaching 63 degrees.
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Sir: My backyard advise would be add gas slowly till the line sweats at the compressor. If it is sweating at the compressor and still no cool you got an air circulation or unwanted heat issue.
C. Boyd
76 Crestmont
East Tennessee
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| Re: Stupid AC, 20psi, 120psi...73degrees [message #137788 is a reply to message #137787] |
Sat, 06 August 2011 19:16 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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| C Boyd wrote on Sat, 06 August 2011 20:09 |
| Keith V wrote on Sat, 06 August 2011 19:25 |
Yep I pulled a vacuum with an AC compressor for a few hours.
Then charged it
The thing that bothers me the most is I have a second evaporator under the couch that is only reaching 63 degrees.
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Sir: My backyard advise would be add gas slowly till the line sweats at the compressor. If it is sweating at the compressor and still no cool you got an air circulation or unwanted heat issue.
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PS: it is easest to pull the fender liner to see the lines. Eventho it sweats at the dryer don`t mean it is sweating at the compressor.
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137798 is a reply to message #137797] |
Sat, 06 August 2011 21:25 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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well the lines up front by the fill valve were wet and cold...
I just hear people talking of 40 degree outlet temps and think I should be a little closer!
64 seems kinda warm for the secondary evaporator
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137803 is a reply to message #137798] |
Sat, 06 August 2011 22:13 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Keith
If things are starting to get a little crazy the easiest way out of your delima is to release the charge. Pull a short vacuum and add 3 cans of Duracool possibly a tad less, then with the engine idling at 1500 RPM and a water mist on the condenser check the air out of the evaporator it should be cold from both evaporators and the suction should be around 25 lbs. if it is a lot higher or lower you have other problems. At least this way you know the charge is correct and something else is wrong. It is always easier to trouble shoot a small system when you know you have the correct charge in it.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137870 is a reply to message #137798] |
Sun, 07 August 2011 11:07 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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| Keith V wrote on Sat, 06 August 2011 21:25 |
well the lines up front by the fill valve were wet and cold...
I just hear people talking of 40 degree outlet temps and think I should be a little closer!
64 seems kinda warm for the secondary evaporator
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what kind of air flow are you getting at the outlets? did you manually open the recirc. door forward of the engine hatch?
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137872 is a reply to message #137798] |
Sun, 07 August 2011 11:28 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| Keith V wrote on Sat, 06 August 2011 19:25 |
well the lines up front by the fill valve were wet and cold...
I just hear people talking of 40 degree outlet temps and think I should be a little closer!
64 seems kinda warm for the secondary evaporator
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Keith: Yes, your temps seem too high, yet some cooling is taking place in both evaporators. I know this sounds like a very long shot, but by any chance could you have some "junk" in the system that has partly plugged both expansion valves. If your dryer got very wet the material inside can force it's way into the system and cause plugging issues. Did you change the dryer? The expansion valves? There are not many really operational parts in these systems, the compressor, the dryer, and the expansion valves. Otherwise it is all hoses and leak problems, which you don't seem to have.
I also assume it worked in the past with other refrigerants, right? You have not built a new system and this is the first time to charge?
All long shots, but I understand your frustration and trying to figure out what strange other things could be happening here.
Rob Allen
former owner of '76 x-PB
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137873 is a reply to message #137870] |
Sun, 07 August 2011 11:29 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Keith, did you clean out the heater/AC box. Critters have an uncanny knack
of finding their way into such places and building their nests. When Mary
was in the hospital I left her Turbocharged PT Dream Cruiser sit and drove
my Ford Bronco II back & forth to Portland during the winter weather. When I
went to drive the PT, it wouldn't hardly run. Took off the air cleaner
cover, and some critter had filled the air intake from the fender well
opening to the air cleaner with pink Owens Corning fiberglas insulation that
it stole from a roll of it I had stored in the carport. Never did see the
critter. I have seen several GMC evaps blocked in similar ways.
I now have an outdoor cat that takes care of most of my critter problems,
she works cheap. Just pick her up and pet her once in a while and feed her
twice a day. She has a thermostatically heated shelter in one of my old cars
that is awaiting restoration.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sun, Aug 7, 2011 at 9:07 AM, fred veenschoten <fredntoni@cox.net> wrote:
>
>
> Keith V wrote on Sat, 06 August 2011 21:25
> > well the lines up front by the fill valve were wet and cold...
> >
> > I just hear people talking of 40 degree outlet temps and think I should
> be a little closer!
> > 64 seems kinda warm for the secondary evaporator
>
> what kind of air flow are you getting at the outlets? did you manually open
> the recirc. door forward of the engine hatch?
>
> --
> Fred V
> '77 Royale RB 455
> P'cola, Fl
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137878 is a reply to message #137872] |
Sun, 07 August 2011 12:05 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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| idrob wrote on Sun, 07 August 2011 11:28 |
| Keith V wrote on Sat, 06 August 2011 19:25 |
well the lines up front by the fill valve were wet and cold...
I just hear people talking of 40 degree outlet temps and think I should be a little closer!
64 seems kinda warm for the secondary evaporator
|
Keith: Yes, your temps seem too high, yet some cooling is taking place in both evaporators. I know this sounds like a very long shot, but by any chance could you have some "junk" in the system that has partly plugged both expansion valves. If your dryer got very wet the material inside can force it's way into the system and cause plugging issues. Did you change the dryer? The expansion valves? There are not many really operational parts in these systems, the compressor, the dryer, and the expansion valves. Otherwise it is all hoses and leak problems, which you don't seem to have.
I also assume it worked in the past with other refrigerants, right? You have not built a new system and this is the first time to charge?
All long shots, but I understand your frustration and trying to figure out what strange other things could be happening here.
|
This seems highly plausible.
The system had some big leaks when I bought it, it never worked.
I put in a second evaporator under the couch from a conversion van of unknown workingness
I had a a/c shop weld up an adapter to run the second evap in parallel
It does have a new dryer
I used the existing expansion valves.
Lots of places for contamination to occur.
Sounds like I should replace both Expansion valves, the dryer and maybe flush the system? ( can I do that?? )
then recharge.
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137886 is a reply to message #137878] |
Sun, 07 August 2011 13:52 |
hal kading
Messages: 642
Registered: February 2004
Location: Las Cruces NM
Karma: 4
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Keith,
You're not alone. Our stretch is marginally better than yours. We're getting:
Outside air 90*
Temp at cooling air duct 60*
Temp inside coach 80* (100% recirc air)
Low side pressure 25 psi
High side pressure 105 psi
We have two evaporators, system flushed, new HT6 4 Seasons compressor with mineral oil, new expansion valves (marked for R134a), new filter dryer, system evacuated and recharged. Put in 3 cans of HC12a and when it wouldn't cool added a can of Freeze 12, (ran out of HC12a). We have lowered the low side pressure to the above from a high of about 30 psi.
When we try for technical support from the AC industry all we get is don't use hydrocarbon refrigerants. Very frustrating. I'm open to all suggestions.
Hal Kading Buskirk Stretch Las Cruces NM
[Updated on: Sun, 07 August 2011 13:52] Report message to a moderator |
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137906 is a reply to message #137878] |
Sun, 07 August 2011 15:49 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| Keith V wrote on Sun, 07 August 2011 10:05 |
| idrob wrote on Sun, 07 August 2011 11:28 |
| Keith V wrote on Sat, 06 August 2011 19:25 |
well the lines up front by the fill valve were wet and cold...
I just hear people talking of 40 degree outlet temps and think I should be a little closer!
64 seems kinda warm for the secondary evaporator
|
Keith: Yes, your temps seem too high, yet some cooling is taking place in both evaporators. I know this sounds like a very long shot, but by any chance could you have some "junk" in the system that has partly plugged both expansion valves. If your dryer got very wet the material inside can force it's way into the system and cause plugging issues. Did you change the dryer? The expansion valves? There are not many really operational parts in these systems, the compressor, the dryer, and the expansion valves. Otherwise it is all hoses and leak problems, which you don't seem to have.
I also assume it worked in the past with other refrigerants, right? You have not built a new system and this is the first time to charge?
All long shots, but I understand your frustration and trying to figure out what strange other things could be happening here.
|
This seems highly plausible.
The system had some big leaks when I bought it, it never worked.
I put in a second evaporator under the couch from a conversion van of unknown workingness
I had a a/c shop weld up an adapter to run the second evap in parallel
It does have a new dryer
I used the existing expansion valves.
Lots of places for contamination to occur.
Sounds like I should replace both Expansion valves, the dryer and maybe flush the system? ( can I do that?? )
then recharge.
|
I am reluctant to suggest throwing parts at the problem (cost of two expansion valves is about $60 I think) but since the system was open and the second evaporator is an unknown, as well as the original GMC one, it may come to that. BTW, a 30 degree air temp drop is kind of normal, depending on the humidity level. I have also read folks achieving a 40 degree outlet air temp from their evaporators, but I had never experienced that on my unit, using duracool. If you do change the expansion valves, be sure that the sensing tube(s) is/are well clamped onto the outlet pipe or you will have freeze problems.
Last thought, I am sure you have checked this but I mention it anyway. Your compressor is running full time isin't it? It is not cycling on and off? The compressor temp control in the main box should not be cycling your compressor. If it is, you will never get really cold air from the two evaporators. The sensor tube for it is in front of the evaporator coil in the main box. It should not be touching the fins, or jammed into the fins. If it is cycling the compressor, by pass it with a jumper and see what happens. If it is not cycling the compressor, this is a dead end idea. Just trying to come up with any idea that you have not mentioned or may not have though of.
Rob Allen
former owner of '76 x-PB
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| Re: [GMCnet] Stupid AC, 20psi, 120psi...73degrees [message #137914 is a reply to message #137765] |
Sun, 07 August 2011 17:11 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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Keith,
Are you sure your engine coolant supply hoses for the heater side of the
HVAC are completely isolated? Many folks have had issues with poor flap
sealing or a HW shut off valve leaking or not working at all.
I have to say that I never could get mine to cool until I hit 30psi on the
low side.
On Sat, Aug 6, 2011 at 1:08 PM, Keith V <my427v8@hotmail.com> wrote:
>
>
> Continuing from this thread;
>
> http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&th=18173&start=0&rid=1431
>
> Or for the Email crowd subject is; More AC questions....
>
> so I bought real (well harbor freight) AC gauges.
>
> * Low side 19 psi
> * High side 120 psi
> * Recirc blocked for 100% recirc
> * engine at 1500 rpm
> * run for 20 minutes
> * heater hose shut off mechanically
> * ambient temp 78 degrees
>
> AC outlet temp is 73 still degrees
>
> Secondary evap temp was 63 degrees
> (this one is definitely 100% recirc!)
>
> What the heck?
>
> Do I have air in the system??
>
> Gremlins?
> Trolls??
>
> Keith, cant see the problem, vasilakes
> --
> Keith
> 69 Vette
> 29 Dodge
> 75 Royale GMC
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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