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Can Opeler
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Discussion Starter · #1 ·
Today I purchased a very nice Opel GT GM AC unit that has about 80% of the parts I need to make my other GT have functional AC. I initially intended to use the unit as spares for my original working ARA unit in my red GT, but this unit is quite honestly leaps and bounds better than the ARA system in terms of engineering and packaging. Very few components are interchangeable and the GM unit is better in almost every way.

More on the differences later. I plan on doing a video on the differences and installation. After I play with it some more I’ll post more info here too. In the mean time, here are some nice pictures!







I will be indeed finding me an original GM A6 compressor in a junkyard to use on this. The compressor will rob roughly 15HP. It is a massive 220cc compressor with 6 axial cylinders!!!
 
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Can Opeler
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Discussion Starter · #3 ·
That compressor looks damn near as big as the engine!
I know! I’m excited to find one and fit the monstrosity on the GT. It’s a 220cc compressor . AKA more than 10% of the engine size lol. I think it’s almost the length of the valve cover.
 

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Opeler
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Nice find, Kyler! I had never seen the GM components laid out like that before and I like the way the evaporator is enclosed in that clamshell case. That stock GM compressor really is a chunk. I had one like that on my '69 Riviera and it took a 430 c.i. engine to drive it, but they are smooth running and effective compared to other designs of the time.

If you aren't firmly set on that large one, but want a factory-style compressor, you might look at the '79 Riviera compressors. They aren't much larger than an alternator and perform well too. I had one of those too, back in the day. They also came on other GM models too, I think.

Here is what they look like. Good Luck!


https://www.buyautoparts.com/buynow...MI76_y1dWk5AIVef_jBx0TNQZQEAQYAyABEgKX4fD_BwE
 

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to bad there was a never an after market behind the dash AC system for the GT

I never liked the center console set up for the GT (ARA or Factory GM)

I look forward to hearing about the differences between the two
 

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Opel Key Master
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Personally I like nothing about the GM units interior parts compared to the ARA. I do think the GM unit was better engineered as far as the engine setup though. With actual formed brackets and hoses running under the car. The belt slipping is a bit problematic for the unit as it has a long stretch that doesn’t have any support or tension against. The only thing about the interior unit is it does retain the shifter surround of the interior of the car, so making it an automatic or 4 speed changes nothing.
When comparing the units back in the day, it was said the GM unit just didn’t do as good of a job
 

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The GM compressor used on 4 cyl. Opels ( Vegas ) did not have all 6 pistons installed and if you use a V8 A6 compressor you will stall the engine.
You will need the new style A/C hoses to work with R134a freon or you will leak freon through the old style A/C hoses.
As Keith stated .. there are better more efficient compressors to work with your A/C.
John
 
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Wow I have never seen one laid out like that before either. How in the world are you going to mount that? Its huge :lmao:
Looking forward to further information and video from you.
Dan
 

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Can Opeler
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Discussion Starter · #10 ·
Kyler, would you be interested in a GM AC factory service manual? I have one.
I will let you know! I ordered a 1972 Opel AC service manual. It may be enough.
 
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Can Opeler
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Discussion Starter · #11 ·
Update #1: day 1 and 2

I scored a compressor off of a 1970s Buick Le Sabre out of a local junkyard. It is the exact model number as the one used on the GT. I am almost certain GM put the full size AC compressor on the GT based on my research.

The compressor still had pressure when I disconnected it from the old Buick!
I believe Opelspyder is also sending me a a NOS Opel Kadett compressor. I’m very excited for that. I will use the NOS one for final use and this Buick one for test fitting.

Day 2
Today I cleaned up all of the metal parts, sand blasted them, and painted them satin black.






I need to order a new pulley ball bearing part NDH 3203. They are about $15.

More in the next few weeks. This project will take some time because I’m filming too.
 

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Cool project! Hopefully everything works out.
 

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Can Opeler
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Discussion Starter · #14 ·
Today and yesterday I got the brackets roughly set up. I’ll be waiting awhile for some strange sized hardware to get shipped to me before I can continue.
I had to do minor surgery on the brake rod support. The compressor won’t fit with some of the metal there. I tried to cut it in the exact spots the dealer did based on a single photo I found.


The compressor is temporarily mocked up along with the alternator. The belts clear just barely without a cooling fan on. With a fan on there is no way José. I’m going to run back to Texas and grab my old metal fan from my ARA AC kit. I think it will clear. I will not put an electric fan on this car. The coil is mounted close to where the dealer moved the original, but I haven’t been able to find where they moved the voltage regulator yet.

 
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Oha
That is a lot of drop down 20hp.When drive a lowe a 71-73 engine and have a automatic, all trucks will pass you:ugh:
Okay you get a cool head.How much the other variations ARA or the new one from Keith
drop down the hp with actuell modern compressor?
 

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Can Opeler
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Discussion Starter · #17 ·
Oha
That is a lot of drop down 20hp.When drive a lowe a 71-73 engine and have a automatic, all trucks will pass you:ugh:
Okay you get a cool head.How much the other variations ARA or the new one from Keith
drop down the hp with actuell modern compressor?
You can definitely feel Keith’s mini sanden compressor kick on when driving on the highway. It might take 5HP when on. When off it takes almost none. Keith doesn’t have an idler pulley, so you only have the friction from a brand new AC clutch and the belt slowing down the engine a tiny bit.

My ARA unit never cooled the car, but I kicked it on one time and it lowered my top speed from 110mph to 88mph. That’s theoretically a loss of over 35HP. I figure the idler pulley or compressor was seizing up because that’s too much power draw.

The GM should draw about 15HP at WOT. But the system uses a vacuum switch so it shouldn’t operate at idle or WOT if you connect the vacuum lines to a ported source.
I might lose 1HP with the system off because of the friction from the belt and pulleys.
 

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Opeler
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Can Opeler
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Discussion Starter · #19 ·
Here’s another short update. I’ll get to writing detailed stuff later. For now here’s some pics. I’m about halfway done and the car is drivable again.



 
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