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#1 |
Senior Member
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Location: Northern Nevada
Posts: 7,237
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Releasing pressure from A/C system?
I have the need to remove the lines connected on back of the A/C compressor. Technically, I just want to see the bolt. The A/C is hooked up, though it's not operable. I can't speak for any Freon or system pressure. If I sound ignorant, it's because I am.
Anyway, safe to assume you release any pressure first? If so, how is that accomplished? Perhaps what's pictured is exactly for that, a pressure release valve? Thank you ![]()
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#2 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Releasing pressure from A/C system?
If you think there's refrigerant in the system, your best bet would be to take it somewhere (pretty much any shop that can service AC) and get it removed (vacuumed out). They actually save it, I think, and you get a credit against what they removed when you go to have it recharged. At least that's the way it works around here (Seattle).
You could just crack a line and let it all escape, but you'd be wasting some money and I suppose it's not a great idea to dump CFCs into the air without reason. Odds are, however, that the refrigerant has been gone for a long time... Backing up a little, though, why do you need to release it? Even if you're pulling the motor you can normally leave it all connected and just place it off to the side.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#3 |
Registered User
Join Date: Nov 2014
Location: Bigfork, Montana
Posts: 1,137
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Re: Releasing pressure from A/C system?
Yes, that valve is used to recover refrigerant & re-charge the system. (there are two, one on the high pressure side & one on the low) You may not need to disconnect the hoses though. If you just want to remove the compressor from the bracket you can unbolt it & move it to the side with the hoses/lines attached. When I do engine swaps this is the way I do it so I don't have to recover / re-charge.
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#4 |
Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Re: Releasing pressure from A/C system?
That is the high pressure side. The valve on the POA valve is the low pressure side. You could press the valve on the low pressure side to see if there is any freon left in the system. Much like releasing air from a tire, make sense?
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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#5 | |
Senior Member
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Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Quote:
Honestly, ha, I want to see what that bolt is, and any other washers or rings with it. The bolt is missing from the truck I'm rebuilding, so I know just where to get one. ![]()
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#6 |
Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Re: Releasing pressure from A/C system?
The single bolt that attaches the line to the compressor can either be SAE or Metric, both compressors are available new or remanufactured. The threads on the SAE are fine thread, not sure of the size. No washer on my 402. I have mine loose now, if you would like a picture let me know.
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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#7 |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Am I on the right track here? See pics., thank you:
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#8 |
Registered User
Join Date: Nov 2014
Location: Bigfork, Montana
Posts: 1,137
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Re: Releasing pressure from A/C system?
You are correct, that is the low pressure port. Both valves are used to recover & re-charge. When the system is off, the pressure is equalized between the high & low sides so it doesn't matter which one you use to release pressure.
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#9 |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Thank you for the confirmation etc. B.W., and others for info.
__________________
Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#10 |
Registered User
Join Date: Feb 2012
Location: Smyrna TN
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Re: Releasing pressure from A/C system?
The truck looks to have all its original a/c parts in place with the exception of the compressor. All of the screws and brackets are present, even the ones on the high pressure hose, and evaporator core. Great picture of how things should look when original. I don't know why the a/c is not working but its definitely worth repairing. Thanks for posting the pictures.
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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#11 | |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Quote:
__________________
Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#12 |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
I pulled the bolt. It's 3/8-24 x 1.3/8. Engineer, there was a washer and lock washer, which is correct per the assembly manual, page 517. The washer has a 3/4" diameter.
This bolt looks original to me, so I decided my 71 project needs it more than the 72 HA!. It's not all bad for the 72. Getting ready to install the newish parts I pulled off the 71, starter, battery, cables, etc. Besides, I can actually drive the 72. ![]() ![]()
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#13 |
Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Re: Releasing pressure from A/C system?
My bolt was missing and F.A.Abenny was nice enough to send me this one.
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1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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#14 |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Not to hijack this thread
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__________________
Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 |
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#15 | |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Quote:
Turns out I got the other bolt after all. It's exact. I have a stash of hardware I've kept so long, but they looked "right", so I never got rid of them. That's twice it's paid off for this A/C, and I couldn't have asked for a better two. I should have mentioned earlier, not a puff released when I depressurized.
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 06-13-2017 at 07:10 PM. |
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#16 |
Registered User
Join Date: Apr 2010
Location: So Cal
Posts: 1,437
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Re: Releasing pressure from A/C system?
>>, not a puff released when I depressurized. <<
Not exactly sure what you really did, but that is a good way to get an eyeball full of refrigerant and oil. Generally you would connect the gauges, which would show how much pressure is in there. Then if you are inclined to just vent it to the atmosphere, you can do it in a controlled manner and you can collect any oil that comes out with the refrigerant.
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'67 GMC 2500, 292, 4spd, AC |
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#17 |
Registered User
Join Date: Feb 2012
Location: Smyrna TN
Posts: 1,153
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Re: Releasing pressure from A/C system?
That's the original expansion valve. It can be rebuilt. Don't throw it away as it's much better than what's available now and that style is no longer made.
__________________
1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN |
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#18 | ||
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,237
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Re: Releasing pressure from A/C system?
Quote:
Yeah, I probably shouldn't have taken a chance DON'T TRY THIS AT HOME KIDS. I did suspect there was a lot of loss beforehand, and was careful. I took a tire gauge to the POA valve and nothing. Then I pulled the bolt off the lines to the compressor & nothing. Might be worth mentioning, that bolt goes on TIGHT. At least that's how I found it. When I put it back on, yeah, wrenched it on but good. I'm new at this, but that's what it seemed to want. Quote:
No plans to revise the AC in this 72. Nice to have the parts though. It's the 71 that gets the makeover, to 134A. New condenser, POA valve, hoses, and a rebuilt compressor. I believe, the existing expansion valve works with 134A?....................I gather the evaporator works with R12 & 134A. But if I recall, (been 25 years), my evap. was exposed to the elements, for maybe a month. That and it's obviously empty, less some oil perhaps........ Not sure the affect. Probably just as well to buy another. I hear they mount the same. So yeah, ha!, somewhat original appearance, but not..............On topic, I have one can of R12. $2.95 price tag, from Grand Auto.
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 06-13-2017 at 11:55 PM. |
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