1979 Chevrolet C70 Conversion to OEM Air Conditioning

[Airdirect]

Making progress, the truck is back in the garage and ready to finish the painting of the cab!

[Airdirect]

Making progress on the body work on the cab. Roof is sanded, hope to get the cowl area and door hinges sanded tomorrow. Next I will tackle the door opening and rear of the cab. If all goes as planned, I should be able to paint it next week.

[Airdirect]

I am looking for a fan and fan clutch that will fit the 4-53T. Mine has a solid fan drive with no clutch.

Thanks

David

[Robert1970C20rstbukt]

Don't believe there ever was a fan clutch for that engine, factory book only lists a direct drive even for a truck with factory A/C.

[Airdirect]

If you look close at this truck, you will note it has a fan clutch. I have seen one other unit (California Truck) that also had a fan clutch. It may be that one was not offered in 1979.

David

[Airdirect]

Here is a picture of a 1979 GMC 7000 with 4-53T equipped with A/C and fan clutch. This picture was on www.4btswaps.com "foxyboxy" forum.

[83GMCK2500]

These look to be the relevant pages for fan clutch stuff:

http://gmpartswiki.com/getpage?pageid=176194
http://gmpartswiki.com/getpage?pageid=176193
http://gmpartswiki.com/getpage?pageid=176192

[Robert1970C20rstbukt]

I didn't think about the GM Wiki page, forgot there are some medium catalogs listed there. Looks like the first design used the same clutch for the 350 and 366, Hayden # is 2801. It has a four bolt pattern on the pulley and fan, looks real similar to the one in the picture.

[Airdirect]

Thanks Robert! Great help, the first design used on the 350 should be fairly common and easier to find. This gives me a good start.

David

[Robert1970C20rstbukt]

You're welcome, credit goes to Devin for finding the parts pages. I'll have to bookmark that catalog. That clutch is also similar to one for a 454, # 2797. You might check the specs on them and see what the mounting dimensions are for the pulley and fan.

[Airdirect]

Here are pictures of progress. Got the cowl, roof, door openings, and rocker panels sanded, rear of cab to go then prime and paint.

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Removed a hail dent from the roof. Installed new left and right doors. Took some adjusting to get them to line up correctly. The original doors fit terrible, I was in hopes the aftermarket doors might align better. In the 1979 era, fit and finish were not anything like today's standards. After some twisting bending and lots of adjusting I got them to fit slightly better than the original OEM doors. Time will tell how they hold up.

[Airdirect]

Made a little progress, transferred mirror mounting holes from old doors to the new. I used masking tape to make a template and then moved the template to the new door. I use multiple layers so it does not stretch when removed and reinstalled. Once the holes were all drilled (used a step drill bit to get a nice smooth hole with no stress risers) I then primed the holes.

[Airdirect]

More progress:

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More progress, I had good help, my sons Noah and Micah were great! Also pictured is my bride (Angie) and yours truly.

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More progress:

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Started putting the cab back together, cowl area is complete, driver side mirror mounts have been installed, once I get the passenger side done I will be working on the cab clearance lights.

[Airdirect]

Got the cab finished! Glad to have this portion of the rebuild done! Purchased a temporary 30 day tag so I could take it to town to have Air Conditioning lines made. When I started to pump the system down I remembered it was configured for R-12. Another trip to the parts store to get the R134A adapters.
I pumped AC system down, serviced with oil charge, then started adding the first can of Freon R-134A. Much to my dismay, I discovered I had fabricated lines that hooked the low pressure side to the discharge of the compressor and the high pressure side was connected to the suction. Some days you just cannot get it right! Hopefully I can figure out a easy fix as I am using the original GM style connectors on the compressor.

[Airdirect]

The fun details, made a conformity sticker to replace the original. I had taken a good picture of it before removal. The sticker was originally printed on a paper label with a clear film over the top. Was able to get sticky project paper at Office Max and clear printable shipping label. I then recreated the sticker using Microsoft Paint, printed it and then cut the clear to fit with the required overlap. It turned out really good. The first picture is the original and the bottom picture is my re-creation.

[Airdirect]

More progress. Got the Air Conditioning finished up. Made new hoses that connected the compressor output to the high side and the suction to the low side. Serviced with oil charge, and 4 cans of 134A. Presto, we have cold cold air blowing out the dash vents. Moving the temp control allows us to blend the temp as advertised. Next we installed the rain gutters over the left and right doors.

[Robert1970C20rstbukt]

Making some good progress! Were you able to get a fan clutch for the 4-53? I'm running R12 in my welding truck and pickup, got a decent deal on two cases a couple years ago. I installed one electric fan on my '84 to help with all the heat the 454 makes, it can get down to freezing with no trouble idling.

[Airdirect]

I have not purchased a fan clutch and fan. I am still looking for one.

[Robert1970C20rstbukt]

Found this on ebay, correct for a medium duty with a 350. That bolt circle would fit on the 2797 fan clutch. Seems like the catalog might have been wrong, as a 2801 clutch is for a 366 and 427 that takes a larger fan. I'm betting this fan and the 2797 will fit your truck if the mounting dimensions are right.

https://www.ebay.com/itm/CHEVROLET-C...YAAOSwH-daKvZX

https://www.rockauto.com/en/moreinfo...793626&jsn=573

[Airdirect]

Thanks Robert, I really appreciate your help!

[Airdirect]

Robert,

My current fan has a 22" diameter. It also has seven blades.

David