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I think I just blew up my A/C
#1
Today I went for a high performance drive during lunch break. It was hot out so I had the A/C on. While accelerating down the highway at some point I lost A/C. A few miles down it started to feel hot inside and could hear a noise from the hood. The noise went away after I turned the A/C off so definitely something was wrong. I just had accelerated to about 6,500 rpms so I had the feeling that I had overrevved the compressor. I guess I didn't think about it before. Before I had only gone to about 6,300 rpms. Once I got home I could see the mess. Oil everywhere, the high pressure hose burst, and the compression nut of the low pressure fitting was completely off. I believe that the system over pressurized and broke. The fact that the coupling nut of the fitting was off makes me think the pressure went pretty high. It was not that it unscrewed itself because that should have released the pressure and should not have caused the hose to burst. The coupling nut is aluminum so I assume that enough pressure expanded it to push it past the threads. I feel dumb now for not having thought about the RPMs of the compressor. My compressor is a York and now reading the spec it says 6,000 rpm  Shootself Angry . On top of that I probably had overfilled the system with refrigerant. My question now, do you think the compressor is done? Am I looking at a new compressor besides the hose? What else should I be worried about? Maybe it is time to upgrade to a whole new system from Classic Auto Air or similar? Can one of these be revved up to 6,500 rpm?

These pictures shows the burst hose. I had already screwed the low pressure fitting nut back in. As you can see the burst is coincidentally very close to the steering fluid radiator. This radiator is attached to the compressor so there shouldn't be independent movement between them, but I wonder if the hose could have moved and touched the radiator and caused it to burst, but unlikely due to how close it was to the fitting. Also, it could simply be that it was the hottest spot on the hose.

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1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes
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#2
The power steering cooler does not get that hot. That is a pressure burst. Looks like that just happen to be the weakest spot on your hose. My guess would be as you stated. The high RPM over pressurized the system, especially if you think it as over charged. As for eh compressor only way to know is to test it out, my guess is it is fine since the hose blew and not the seals on the compressor. You could increase the diameter of compressor pulley or reduce the size of the crank pulley to reduce the RPM at the compressor going forward. Or just make sure to turn the AC off when you are making high RPM runs. Hope this helps. Sorry to hear about the blow up.

73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

- Jason


[Image: 082-hot-rod-power-tour-2017-1970-1970s.jpg]
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#3
I would convert to a sanden compressor and a modern condensor that has larger diameter tubes in it. The sanden can spin at higher RPM without difficulty and is built for modern refrigerants

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#4
Now you know why they did not put any lower gear in the rear than 3.25 with AC.
One of the first things I did when I got my car new was to take the AC belt off, lol.
Would be difficult to change pulley size on the compressor since it is the clutch. I am sure a newer model compressor would be better just will not look correct. But unless you are trying to be perfect doesn't matter.
I was in Charlotte last weekend and in high 90's did not have air and did not really bother me. It is not a dry heat here with all the humidity either.
Don't know that you need to change the whole system just the compressor and hoses maybe.


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#5
(07-03-2019, 08:43 AM)Jeff73Mach1 Wrote: I would convert to a sanden compressor and a modern condensor that has larger diameter tubes in it.  The sanden can spin at higher RPM without difficulty and is built for modern refrigerants
Thanks. I am leaning toward a whole new system from Classic Auto Air: https://www.classicautoair.com/shop/1971-ford-mustang-air-conditioning-system/
I
t will be a bit more expensive but everything will be new. However, I am not looking forward to disassembling the whole interior to install the evaporator.

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes
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#6
that classic auto air system is great. I love the video from autoediits. I like the electronic valves instead of vacuum controlled.

https://www.youtube.com/watch?v=Y2AszX591GM

"I drank what?" - Socrates
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#7
I believe the rev limiter for the 429 SCJ was at 6150 rpm's, and AC was not offered for those cars. I know you don't have the 429 SCJ but it tells you they did not want to have the AC compressor running at that rpm level. I think the rev limiter would have been set at 5800 rpm's for my 429 CJ. I never shift anywhere near there. My Ferrari has a 7700 rpm redline but even in that car I shift at around 5000 rpm's at the highest normally. That car still has nice cold R-12 AC in it.
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#8
Here is a kit were you use your orginal evaporator, I used their kits and have been happy with them.
https://originalair.com/71-73-ford-musta...r-brackets
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#9
You don't have to disassemble much if you will pull the glove box, the dash cap and the passenger seat everything else can accessed without much difficulty. You will need to take apart the center stack, but that is easy

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#10
You CANNOT use r134 with older compressors, they are not rated for higher pressure that the newer freon requires. I went through same issue years back on 1977 460/york style r134 combo. put a sanden unit on or spend$$$ and convert back to r12.
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