134a what size orifice - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chris989 · 07-23-2024, 10:32 PM

Hello all,
1989 v2500 suburban

While chasing a leak,, I installed a new fixed white orifice and now the low pressure is a little high and it will not pull temps lower the ~60 at the vent.

I pulled out a VOV valve that was a little dirty and did not take note of the color.

I am thinking of pumping back down and installing a .067.

What did others use? How many Ounces of 134 did you use?

Thanks,
Chris

v30crewcab · 07-25-2024, 08:11 PM

the .067 should work good. I think thats what is in my truck.

chris989 · 07-25-2024, 10:05 PM

I reinstalled the VOV
https://www.napaonline.com/en/p/TEM207325

i have 42-48 degrees at the vent

**Hart_Rod** · 07-26-2024, 12:35 PM

Quote:

Originally Posted by chris989

I reinstalled the VOV
https://www.napaonline.com/en/p/TEM207325

i have 42-48 degrees at the vent

Just curious why did you chose that one?

**hatzie** · 07-27-2024, 07:55 PM

I've used the .067" Ford Blue orifice tubes and VOV for R12 to R134a conversions. The C4 Vette guys prefer the Ford Blue tubes rather than the VOV.
Variable orifice valves have been hit or miss for me as they aged. I used to recommend them. I've come to the conclusion that moving parts are not a great thing for long term reliability.

v30crewcab · 07-27-2024, 08:46 PM

whats the part # for the ford blue tube?

**hatzie** · 07-27-2024, 09:21 PM

Four Seasons 38621

chris989 · 07-28-2024, 10:42 AM

Quote:

Originally Posted by Hart_Rod

Just curious why did you chose that one?

It is what I used when i swapped from 12 to 134. I only went white fixed because I had it on the shelf and that is what is called for.

I am using a Sanden SD7,, With the fixed i could not get decent temps.. My motor runs around 2,000 or less in town.

Chris

**hatzie** · 07-28-2024, 05:19 PM

Quote:

Originally Posted by chris989

It is what I used when i swapped from 12 to 134. I only went white fixed because I had it on the shelf and that is what is called for.

I am using a Sanden SD7,, With the fixed i could not get decent temps.. My motor runs around 2,000 or less in town.

Chris

The white GM orifice is 0.072
That's just fine for hydrocarbon R290 and R12.

You need a slightly smaller orifice for R134a and HFC152.
As I said the Ford blue is 0.067 and it seems to do the job.

**Hart_Rod** · 07-29-2024, 09:07 AM

Quote:

Originally Posted by chris989

It is what I used when i swapped from 12 to 134. I only went white fixed because I had it on the shelf and that is what is called for.

I am using a Sanden SD7,, With the fixed i could not get decent temps.. My motor runs around 2,000 or less in town.

Chris

Quote:

Originally Posted by hatzie

The white GM orifice is 0.072
That's just fine for hydrocarbon R290 and R12.

You need a slightly smaller orifice for R134a and HFC152.
As I said the Ford blue is 0.067 and it seems to do the job.

Gotcha. I talked to a local Hotrodder than runs an AC shop. He recommended the white one, so that's what I used when I did the LT swap in my 84 (Sanden compressor/134A). So far, it cools great with no issues. Hatzie - what symptoms should I look out for that might suggest that I switch to the blue one?

**hatzie** · 07-29-2024, 01:22 PM

Quote:

Originally Posted by Hart_Rod

Gotcha. I talked to a local Hotrodder than runs an AC shop. He recommended the white one, so that's what I used when I did the LT swap in my 84 (Sanden compressor/134A). So far, it cools great with no issues. Hatzie - what symptoms should I look out for that might suggest that I switch to the blue one?

Higher vent temps when you're in traffic with the engine idling or near idling.
If your set up is working I'd stick with it.

**Hart_Rod** · 07-30-2024, 10:03 AM

Quote:

Originally Posted by hatzie

Higher vent temps when you're in traffic with the engine idling or near idling.
If your set up is working I'd stick with it.

Thanks. Will report back if I see any changes.

Rob

07-23-2024, 10:32 PM	#1
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 574	134a what size orifice Hello all, 1989 v2500 suburban While chasing a leak,, I installed a new fixed white orifice and now the low pressure is a little high and it will not pull temps lower the ~60 at the vent. I pulled out a VOV valve that was a little dirty and did not take note of the color. I am thinking of pumping back down and installing a .067. What did others use? How many Ounces of 134 did you use? Thanks, Chris

07-25-2024, 08:11 PM	#2
v30crewcab Registered User Join Date: Apr 2012 Location: Chatt Tn Posts: 978	Re: 134a what size orifice the .067 should work good. I think thats what is in my truck. __________________ 88 military v30 crewcab shortbed 5.9 cummins, nv4500, 205 86 k30, 89 diesel burb, 76 gmc pathfinder 71 longbed 5.3 4l80 http://67-72chevytrucks.com/vboard/s...d.php?t=522535

07-25-2024, 10:05 PM	#3
chris989 Registered User Join Date: Dec 2011 Location: Boise, Idaho Posts: 574	Re: 134a what size orifice I reinstalled the VOV https://www.napaonline.com/en/p/TEM207325 i have 42-48 degrees at the vent

07-27-2024, 07:55 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,975	Re: 134a what size orifice I've used the .067" Ford Blue orifice tubes and VOV for R12 to R134a conversions. The C4 Vette guys prefer the Ford Blue tubes rather than the VOV. Variable orifice valves have been hit or miss for me as they aged. I used to recommend them. I've come to the conclusion that moving parts are not a great thing for long term reliability. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-27-2024, 08:46 PM	#6
v30crewcab Registered User Join Date: Apr 2012 Location: Chatt Tn Posts: 978	Re: 134a what size orifice whats the part # for the ford blue tube? __________________ 88 military v30 crewcab shortbed 5.9 cummins, nv4500, 205 86 k30, 89 diesel burb, 76 gmc pathfinder 71 longbed 5.3 4l80 http://67-72chevytrucks.com/vboard/s...d.php?t=522535

07-27-2024, 09:21 PM	#7
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,975	Re: 134a what size orifice Four Seasons 38621 __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.



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