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Old 08-18-2005, 10:20 AM   #1
mvpco
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Expansion Valve Question 72 C10

Hi All!

I have Factory A/C installed in my 72 C10, 350/At/PS/PB
Converted to R134a

I chave not changed out the POA or Expansion Valve.

I am only getting 60-62 Degrees out at the vents. I have added more 134a(2 cans) and it still stays in the blue area on the gauge.

My Question is: Can it be the Expansion or POA Valve?


Jeff Smith
Pensacola, FL
hrrp://www.mvpc.com/1972chevy.htm
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Old 08-18-2005, 01:23 PM   #2
mrein3
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You need to read this faq from a different forum:

Link to POA Adjustment

Without this adjustment you won't get much colder air than that.
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Old 08-18-2005, 07:14 PM   #3
chipflyer
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Hi Jeff
I followed the directions in the above mentioned forum last year to adjust my POA valve on my 71 and had great success. I have a completly stock setup and aveage between 42 and 46 degrees out of the left hand ball vent. You will not get it to cool properly unless you adjust the POA valve if using 134A. Do a little research on that A/C forum, it is full of great information.

Good luck
Jeff
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Old 08-18-2005, 09:37 PM   #4
mvpco
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Expansion Valve

Thanks, I have read it and WOW!! what a great source



Thanks!!!!

Jeff
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Old 08-18-2005, 10:15 PM   #5
chipflyer
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This should be added to the FAQ section, seems to come up every now and then. That A/C forum has great info on it.

Jeff
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Old 08-19-2005, 01:01 AM   #6
GSFMECH
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I agree with everything said above. One other alternative is to use a POA eliminator in place of the POA valve made by Old Air products. It has an adjustable pressure switch installed in it and cycles the compressor like a later model truck. I have one on my 72 and it is the ticket. I have 48 to 50 degree air coming out of mine ( W/ 134A) depending on the ambient and how long I run it.
Mike
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Old 08-19-2005, 08:17 AM   #7
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A couple of Guys on the A/C board say the adjusted poa works better,one is the guy who came up with the adjusting procedure{Mitch,who has since passed on}.I am getting 40- 45 out of my 71 suburban,depending on ambient temp.Make sure you aregetting plenty of airflow.If you havn't put a fan cluth on lately,it will greatly improve the a/c.At 1500rpm,I was getting high pressure readings and vent temps of 50.Put a new clutch on ,dropped the pressure from 325psi to 285,and the vent temp from 50 down to 45 on a 97 degree day.
Get a proper set of gauges,ones that read high and low side.
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Old 08-19-2005, 08:55 AM   #8
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My bro has the POA eliminator, has 42 degree air @ 95* ambient out of center vent, playing w/cycling switch adjustment & charge got it cold. He also is running the two electric fans from Old Air, made a HUGE difference over the engine driven fan. Head pressure around 275. He does residential/comm. A/C for a living. Truck is also well insulated & tight. I get cold riding in the truck. Brian

Last edited by 64fleetside; 08-19-2005 at 08:56 AM.
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