AC Rebuild 72 with CA emissions questions

[ngnaz]

I bought a 72 Blazer that the AC is partially disassembled and missing parts. Is there a good place to see diagrams of wha this plumbing should look like? I looked at the diagrams of LMC and it looks different than mine. Is it becasue it was equipped with CA emissions? The AC Box has a bracket on it where a vacuum canister might be?

Her are a few pics

[DeadheadNM]

A quick search here for “ac hose routing” should turn up some GM diagrams. Yes, that bracket supports an vacuum ball - bracket is 4wd specific.

Get the 72 service manual and the factory assembly manual if you plan to do deep dives into rebuilding the truck - both very valuable.

[Steeveedee]

The missing part in pic #3 is the vacuum-assisted valve that closes the air flapper so that only the air in the cab is recycled, instead of taking in outside air.

There do not appear to be any emissions related parts in your pictures, but maybe I'm missing something?

[Richard]

Nothing with emissions should effect the A/C. As said the canister relocation bracket is 4x4 specific. The factory vacuum cannister in the 4x4 72's is not the ball type that is reproduced from what I have seen. Do not have a picture handy at the moment. Can post one tomorrow.

[ngnaz]

Thanks for the replies. I will look for a service manual as that is a good suggestion. I did not realize the 4x4 was different either.

[DeadheadNM]

You bet. My Blazer has an intact CA emissions system and AC - lots of hoses for sure.

[phlegm]

disregard, cant find my pics with the POA Valve.............

[ngnaz]

Originally Posted by DeadheadNM

You bet. My Blazer has an intact CA emissions system and AC - lots of hoses for sure.

Thanks, just read through your Blazer build thread. Very impressive. So the ball cannister is unique to 4x4 or just tthe bracket?

[DeadheadNM]

Originally Posted by ngnaz

Thanks, just read through your Blazer build thread. Very impressive. So the ball cannister is unique to 4x4 or just tthe bracket?

Thank you! Still working out bugs but no regrets.

The bracket is unique to 4wds w AC whereas that plastic vacuum ball/canister reservoir is also seen on 2wds. The plastic example replaced an earlier model year (pre 71?) piece that was metal and resembled a soup can.

[ngnaz]

Originally Posted by DeadheadNM

Thank you! Still working out bugs but no regrets.

The bracket is unique to 4wds w AC whereas that plastic vacuum ball/canister reservoir is also seen on 2wds. The plastic example replaced an earlier model year (pre 71?) piece that was metal and resembled a soup can.

Thanks that helps.
Out of curiosity, do you know why the 4x4 would be different? What under the ood would make it not work on 2wd? Just wondering if you know.

I just ordered an assembly manual online so I can try to piece this together.

[Steeveedee]

There is an Excel spreadsheet that gives the page numbers for the components that are installed, as the manual doesn't have page numbers. I have it but don't seem to be able to upload it.

Anyone remember where that spreadsheet is located?

Here is a link to the service manuals.

http://67-72chevytrucks.com/vboard/s...ghlight=hatzie

[DeadheadNM]

Not sure but I suspect it has something to do with the engines being set back three inches relative to 2wd models in order to get the reservoir up and out of the way.

Good point about the excel doc - I don’t have the link. My copy is all dog eared and tabbed now.

[Richard]

The type of cannister I have seen on 72 4x4's

[ngnaz]

Originally Posted by Richard

The type of cannister I have seen on 72 4x4's

Thanks, I guess the next question is do they still make these or does the ball style work and fit? If not what are people doing for replacement. I just searched a few sites and see the ball style but not this one unless I am looking in teh wrong places.

[Richard]

Have not seen a source for this style. The ball type should function the same.