How to replace orifice tube

XJSHEN

MEMBER
2003 PONTIAC MONTANA
3.4L
V6
2WD
AUTOMATIC
72,000 MILES

I want to replace Orifice tube, but the work is difficult since the space is limited and I do not know the special tools necessary effectively release the nuts at high pressure line fitting in order to replace orifice tube. I know the location and know one small nut size is 11/16, but I could not measure the bigger nut size exactly, as I estimated was 13/16. Is it right? And what kind of wrench is necessary (name of wrench) or other best one? Thanks for your help!

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7 Replies

HMAC300

MECHANIC
48,601 POSTS

First the nuts are metric. but you must first evacuate the system to get it empty before replacing orifice 13/16 like you say may be 18 mm and other is probably a 15 or 16mm crowsfoot will work. On one see link.
https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

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Saturday, July 29th, 2017 AT 4:03 PM

XJSHEN

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203 POSTS

Thanks a lot!
Yes. I know that many other screws in GM parts were shown with metric. The back up wrench should be the answer for the tool. The Small nut is 19mm and big nut is 23mm at expansion valve connection? I already discharged my system, and doing rebuilding now. It is still not clear about the size.

Thanks for your prompt reply and help!
I was wrong there was no 11/16 nuts. I measured several time in different ways. The small one is 19mm, and the other big nut is around 15/16 inch area and 23 mm in metric.

There is no way exist your mentioned 15, 16, and 18mm nuts on the expansion tube joint nuts on my car. Pointac Montana 2003, and transferred from Canada by dealer. That may be caused differences. Also, the area structure on the expansion tube connection is more complicated than shown on the Hans repair manual. There is T connection.

Thanks! If any techs can help with this topic?

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Sunday, July 30th, 2017 AT 8:03 AM

KEN L

MASTER CERTIFIED MECHANIC
42,878 POSTS

Yes the T connection is there because you have rear air. Proceed as you normally would.

Please let us know what happens.

Cheers, Ken

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Sunday, July 30th, 2017 AT 11:41 AM

XJSHEN

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203 POSTS

Hi Ken, Nice to hear from you again. I just could not recognize the two nuts size at expansion tube. I want to buy but do not know the sizes exactly. 15/16 or23-24mm for big, 19mm or 20mm for small one. If Crowfoot Flare Nut Wrench is suitable to release them?
I will appreciate much your help to resolve the problem. I search a lot of sites but could not find it.

My question is if Crowfoot Flare Nut Wrench set can be used effectively release the nuts on the expansion valve to replace orifice tube on Pontiac Montana? Is it right sizes for small nut is 3/4 inch or 19mm in metric and for big nut is 15/16 inch or 23mm in metric. It is really looks like that GM car repair is very difficult. Few people really conducted this job. If anyone on this site could answer the question? Thanks!

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Sunday, July 30th, 2017 AT 12:21 PM

XJSHEN

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203 POSTS

I am sorry that I was wrong with orifice tube on Montana 2013. There was no orifice tube when I release this joint with 15/16" and 20" fraction flare nut wrench. There is expansion valve instead of orifice tube in 2013 cars.