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Hi, I recently brought my 1994 z28 to a shop to have the air conditioning fixed. The shop wasn’t able to do it, stating they need the high-pressure service port that is no longer available and they can’t find it. Does anyone on here know where I can find that part or a suitable aftermarket replacement? Even used could work. The guy at the shop says I need to replace the whole line, it doesn’t have a Schrader valve. I need the line that goes between the condenser and the dryer.
Last edited by Chiaronate; Aug 28, 2024 at 03:30 PM.
Shoebox has a diagram of the A/C piping. It shows the part number for the line between the dryer and the condenser. Yours almost looks like someone took the valve core out and substituted a screw.
Shoebox has a diagram of the A/C piping. It shows the part number for the line between the dryer and the condenser. Yours almost looks like someone took the valve core out and substituted a screw.
That’s what the mechanic did, he said he couldn’t find the replacement part. He tried putting the screw in with an O-ring underneath and it still leaked out. apparently the original part was a plastic ball valve. I guess the entire line has to be replaced to fix it. He said he has the part number and still couldn’t find a replacement, either oem or aftermarket.
A Schrader valve has a valve core the looks like (but is not exactly like) a tire valve core. I would think that GM is using industry standard parts across their several vehicle lines, and that a replacement core would be readily available. Or was this a case where someone damaged the body of the Schrader valve and a new core couldn’t be installed.
The entire valve assembly is threaded on to the pipe, as shown in the diagram and is replaceable. Did the shop check for a replacement part?
In the event it actually needs a full replacement pipe, did you do an online search for the part number shown in the Shoebox diagram? That is a reproduction of the diagram from the factory parts manual. And if it's discontinued, and you can’t find just the valve, and you can’t just replace the valve core, try a salvage yard or a source like Hawk's Motorsports. They have a field full of salvage vehicles that they use only for parts. I don’t see it listed under engine/cooling parts, but might be worth a call to ask about the part.
And there must be shops capable of making one of these, based on your existing piece. I'm surprised this is such a problem for your A/C shop. But trying to replace the valve core with a screw and an o-ring sounds bizarre.
A Schrader valve has a valve core the looks like (but is not exactly like) a tire valve core. I would think that GM is using industry standard parts across their several vehicle lines, and that a replacement core would be readily available. Or was this a case where someone damaged the body of the Schrader valve and a new core couldn’t be installed.
The entire valve assembly is threaded on to the pipe, as shown in the diagram and is replaceable. Did the shop check for a replacement part?
In the event it actually needs a full replacement pipe, did you do an online search for the part number shown in the Shoebox diagram? That is a reproduction of the diagram from the factory parts manual. And if it's discontinued, and you can’t find just the valve, and you can’t just replace the valve core, try a salvage yard or a source like Hawk's Motorsports. They have a field full of salvage vehicles that they use only for parts. I don’t see it listed under engine/cooling parts, but might be worth a call to ask about the part.
And there must be shops capable of making one of these, based on your existing piece. I'm surprised this is such a problem for your A/C shop. But trying to replace the valve core with a screw and an o-ring sounds bizarre.
it is a GM thing, they made the high pressure valve that way because it can have up to 200 pounds of pressure, the mechanic said. I may have found one on the worldpartsdirect website, I placed an order. I am waiting for shipping information, not sure if it is actually available.
Last edited by Chiaronate; Aug 29, 2024 at 03:58 AM.
it is a GM thing, they made the high pressure valve that way because it can have up to 200 pounds of pressure, the mechanic said. I may have found one on the worldpartsdirect website, I placed an order. I am waiting for shipping information, not sure if it is actually available.
Well it’s back to searching for the part, I called to verify if they have it and was told it wasn’t seen in inventory. Maybe I’ll have to have it custom made or braze the part that I have.
I was poking around the 'net and found that at some point, GM started using a "ball valve" on the high side port. They were apparently prone to leaking. Maybe that is the source of the A/C shop's problem. Just a guess.
Well that’s what it is, the dreaded plastic ball valve. I like the idea of welding it closed. Brazing, as someone called it. Just don’t know who would be willing to do it. Custom making a line sounds better if it would have a readily available fitting. I read that Napa would be willing to do that?
The objective is not to weld it closed so it can’t leak. How are you going to check the high side pressure when servicing the system.
The Shoebox diagram, which is copied from a GM manual shows the Schrader valve as a separable (threaded?) connection to a threaded stub that is brazed to the pipe. Your picture appears to show two “hex” projections at the bottom of the valve. One of those would be on top of the brazed stub. That is there to hold a wrench to prevent the stub from being damaged or ripped off when you use a similar wrench on the hex at the bottom of the Schrader valve to unscrew and to reinstall the valve. That’s what I think I see…….. and it would be compatible with the GM parts diagram.
Looking at the actual valve assembly and not at the photo, does it appear my description above is correct? If so your A/C mechanic would only need to remove the problematic Schrader valve and find a compatible replacement high side valve with a typical valve core, rather than the problematic ball valve type.
Or maybe I'm way off base with this. If I still had my Formula, I could go look. But even then the A/C had been deleted. If I can access the pile of removed parts in the attic over the garage, I'll see if I got that part back from the shop that removed the A/C when they installed the stroker engine 24 years ago. But being that I'm recovering from a hip replacement, I'm not sure I can get to the attic.
The objective is not to weld it closed so it can’t leak. How are you going to check the high side pressure when servicing the system.
The Shoebox diagram, which is copied from a GM manual shows the Schrader valve as a separable (threaded?) connection to a threaded stub that is brazed to the pipe. Your picture appears to show two “hex” projections at the bottom of the valve. One of those would be on top of the brazed stub. That is there to hold a wrench to prevent the stub from being damaged or ripped off when you use a similar wrench on the hex at the bottom of the Schrader valve to unscrew and to reinstall the valve. That’s what I think I see…….. and it would be compatible with the GM parts diagram.
Looking at the actual valve assembly and not at the photo, does it appear my description above is correct? If so your A/C mechanic would only need to remove the problematic Schrader valve and find a compatible replacement high side valve with a typical valve core, rather than the problematic ball valve type.
Or maybe I'm way off base with this. If I still had my Formula, I could go look. But even then the A/C had been deleted. If I can access the pile of removed parts in the attic over the garage, I'll see if I got that part back from the shop that removed the A/C when they installed the stroker engine 24 years ago. But being that I'm recovering from a hip replacement, I'm not sure I can get to the attic.
that’s what I figured, but I guess not. The whole line needs to be replaced. Can a rubber hose be put in place of this with fittings attached or is the high pressure too much for rubber hose?
You'll have to ask your A/C mechanic about a rubber hose. Pressure would be less of a problem, than whether the hose would be compatible with R134A refrigerant and the PAG oil. Then there's the issue of whether the rubber hose would shed material that could damage the system. There are shops that specialize in making metal tubing replacement parts for cars - brake lines, fuel line, high pressure lines for truck hydraulic systems, etc.. I don't know of any specific shop, because I've never needed anything like that. On the other hand, my entire fuel system was constructed of PTFE lined, braided S/S hoses, as was the entire nitrous system which operates normally at about 1,000 PSI max.
You'll have to ask your A/C mechanic about a rubber hose. Pressure would be less of a problem, than whether the hose would be compatible with R134A refrigerant and the PAG oil. Then there's the issue of whether the rubber hose would shed material that could damage the system. There are shops that specialize in making metal tubing replacement parts for cars - brake lines, fuel line, high pressure lines for truck hydraulic systems, etc.. I don't know of any specific shop, because I've never needed anything like that. On the other hand, my entire fuel system was constructed of PTFE lined, braided S/S hoses, as was the entire nitrous system which operates normally at about 1,000 PSI max.
ok thanks, I asked someone at work for ideas and he gave me the name of a nearby hydraulics business. The guy I spoke with on the phone mentioned he may be able to braze the fitting closed or drill it out and put something in it, I forget what he said but it sounds like there are various options. I will check it out when I get my car out of the shop.
