What is this? *Images* - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mpierce9 · 02-26-2016, 03:23 PM

I believe this is the Orifice Tube. I removed it from the A/C pressure hose just at the accumulator.
I've googled Orifice tubes and cannot find a similar looking item to the pictures below.
I want to confirm what this is and what I can replace it with. In the third picture you can see inside, there is a broken tip.
During removal of this object there was several small metallic shards that I imagine were the part of what has broken off.
This is from a 1975 Blazer with Factory A/C.

**mongocanfly** · 02-26-2016, 05:54 PM

Try air conditioning expansion valve orfice...p/n 3031086

mpierce9 · 02-27-2016, 08:29 AM

Quote:

Originally Posted by mongocanfly

Try air conditioning expansion valve orfice...p/n 3031086

Awesome! Thank you very much. These aren't made anymore and haven't been for some time. Any idea what is used to replace this part?

Katrina/10 · 02-27-2016, 09:09 AM

I have never seen one of those. The orifice tube is plastic which is inserted into the inlet pipe of the evaporator.

**mongocanfly** · 02-27-2016, 09:55 AM

Most are plastic but obviously this one is brass..there may be a plastic replacement for it though..I would find a good a/c man to find out.

Firebirdjones · 02-27-2016, 10:13 AM

I use Classic Auto Air fairly often when converting classic cars, or even just looking for parts. They have a ton of oddball and updated stuff. They are over in Texas. Matter of fact I just used one of their conversion kits with a new sanden compressor and hoses for a 69 mustang I'm working on for a customer. You might find they have a replacement made of plastic. Worth a shot.

68Timber · 02-27-2016, 11:05 AM

That's an interesting failure. Looks like copper or brass fragments?

**hatzie** · 02-27-2016, 02:03 PM

It's what GM called an expansion tube. There's supposed to be a screen on the end opposite the bronze filter. You'll want to flush the pieces of that screen out of the line if you didn't pull it off during removal.

Download the 1973 service manual. It has a lot of AC theory of operation including a description of this tube and what it does.
The GM Service Training Group Textbook "11004_00_2_FUNDAMENTALS_OF_AIR_CONDITIONING" has a lot of basic info too.

Did a lot of black goo come out with that filter?

02-26-2016, 03:23 PM	#1
mpierce9 Registered User Join Date: Nov 2013 Location: ATLANTA Posts: 223	What is this? Images I believe this is the Orifice Tube. I removed it from the A/C pressure hose just at the accumulator. I've googled Orifice tubes and cannot find a similar looking item to the pictures below. I want to confirm what this is and what I can replace it with. In the third picture you can see inside, there is a broken tip. During removal of this object there was several small metallic shards that I imagine were the part of what has broken off. This is from a 1975 Blazer with Factory A/C.

02-26-2016, 05:54 PM	#2
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,670	Re: What is this? Images Try air conditioning expansion valve orfice...p/n 3031086

02-27-2016, 09:09 AM	#4
Katrina/10 Registered User Join Date: Oct 2010 Location: Ocean Springs, MS Posts: 1,746	Re: What is this? Images I have never seen one of those. The orifice tube is plastic which is inserted into the inlet pipe of the evaporator. __________________ Gary 1971 Chevrolet C/10 1951 GMC 100 1977 GMC C15 1955 Chevrolet 3100

02-27-2016, 09:55 AM	#5
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,670	Re: What is this? Images Most are plastic but obviously this one is brass..there may be a plastic replacement for it though..I would find a good a/c man to find out.

02-27-2016, 10:13 AM	#6
Firebirdjones Registered User Join Date: Oct 2009 Location: Prescott, Arizona Posts: 2,396	Re: What is this? Images I use Classic Auto Air fairly often when converting classic cars, or even just looking for parts. They have a ton of oddball and updated stuff. They are over in Texas. Matter of fact I just used one of their conversion kits with a new sanden compressor and hoses for a 69 mustang I'm working on for a customer. You might find they have a replacement made of plastic. Worth a shot.

02-27-2016, 11:05 AM	#7
68Timber I know the pieces fit Join Date: Nov 2007 Location: MONTGOMERY, AL Posts: 5,523	Re: What is this? Images That's an interesting failure. Looks like copper or brass fragments? __________________ John 79 2wd Blazer (Bruiser) 85 M1009 Blazer (Sarge) build 74 Honda Z50 build

02-27-2016, 02:03 PM	#8
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: What is this? Images It's what GM called an expansion tube. There's supposed to be a screen on the end opposite the bronze filter. You'll want to flush the pieces of that screen out of the line if you didn't pull it off during removal. Download the 1973 service manual. It has a lot of AC theory of operation including a description of this tube and what it does. The GM Service Training Group Textbook "11004_00_2_FUNDAMENTALS_OF_AIR_CONDITIONING" has a lot of basic info too. Did a lot of black goo come out with that filter? __________________ 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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