Expansion Valve Question 72 C10 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mvpco · 08-18-2005, 10:20 AM

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

mrein3 · 08-18-2005, 01:23 PM

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.

chipflyer · 08-18-2005, 07:14 PM

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

mvpco · 08-18-2005, 09:37 PM

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

Thanks!!!!

Jeff

chipflyer · 08-18-2005, 10:15 PM

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

**GSFMECH** · 08-19-2005, 01:01 AM

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

smokekiki · 08-19-2005, 08:17 AM

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.

64fleetside · 08-19-2005, 08:55 AM

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

08-18-2005, 10:20 AM	#1
mvpco Registered User Join Date: Apr 2005 Location: Pensacola, FL Posts: 400	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

08-18-2005, 01:23 PM	#2
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	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. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

08-18-2005, 07:14 PM	#3
chipflyer Registered User Join Date: May 2004 Location: Topeka, Ks Posts: 2,293	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 __________________ I'm not a pessimist, I'm just optimistic that bad things are going to happen. 1971 Cheyenne Super K10 - tilt, cruise, air, am/fm, tow hooks, factory buckets! 1986 Jeep J10 pickup, - 5.3L Vortec with 4L60e and NP241.

08-18-2005, 09:37 PM	#4
mvpco Registered User Join Date: Apr 2005 Location: Pensacola, FL Posts: 400	Expansion Valve Thanks, I have read it and WOW!! what a great source Thanks!!!! Jeff

08-18-2005, 10:15 PM	#5
chipflyer Registered User Join Date: May 2004 Location: Topeka, Ks Posts: 2,293	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 __________________ I'm not a pessimist, I'm just optimistic that bad things are going to happen. 1971 Cheyenne Super K10 - tilt, cruise, air, am/fm, tow hooks, factory buckets! 1986 Jeep J10 pickup, - 5.3L Vortec with 4L60e and NP241.

08-19-2005, 01:01 AM	#6
GSFMECH On the road Join Date: Jan 2004 Location: NATCHITOCHES LOUISIANA Posts: 815	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 __________________ Mike Castro- 72 SWB. Ochre and White. 496/400 turbo, GV OD ,Dakota Digital dash , tilt, Vintage Air, PS, hydro boost, factory buckets, console, QA-1 Coil over suspension, 20/20"Billet Specialties Magnetos 72 SWB. Med blue. 454/400 turbo, tach, tilt, Stock AC, PS,PDB, factory buckets, console, ECE 4/6 drop w/ 2" blocks and C-notch, 20/20"Coys- Crashed and destroyed by drunk driver Sept 2019. New 72 build in the works. My new build thread "Castro" https://67-72chevytrucks.com/vboard/...d.php?t=820934 My old build thread, the blue truck http://67-72chevytrucks.com/vboard/s...d.php?t=271489 www.louisianaclassictruckclub.com

08-19-2005, 08:17 AM	#7
smokekiki Mike Join Date: Jan 2003 Location: west chester pa Posts: 2,474	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. __________________ 70'c/10, 71 suburban4x4 402bb, 72suburban 4/6 drop, 72k/5 4x4 blazer 4" lift 35 tires

08-19-2005, 08:55 AM	#8
64fleetside Registered User Join Date: Apr 2004 Location: arkieland Posts: 1,070	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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