What seal just blew up?

93CalypsoConvert · May 30, 2022

AC was working fine until one day I open my hood to find this seal blown, along with AC oil all over my battery. System still has a charge, but I haven't turned it back on since.

What seal is this? Over pressure somehow? A while ago I fixed my AC. Pulled a full vacuum and held, then charged with 24oz of R134a and the approprate amount of pag oil. (R134a conversion kit installed)

90sickfox · May 30, 2022

Your orifice tube may be clogged. It's located inside the kine running from the condenser along the passenger frame rail and to the evaporator. You'll need the whole line. That isn't a seal but a pressure valve. Best to replace that also after they blow. If there isn't enough airflow through the condenser and radiator it can cause the AC system to overheat causing high pressure and popping the valve.

When you get the new orifice line cut the old one open. Theres a screen in there. You are looking for metal. If metal is in there then you will need to flush the system.

I only use esther oil in my r12 to r134 conversions. PAG oil doesn't mix well with the old mineral oil.

limp · May 30, 2022

90sickfox said:
When you get the new orifice line cut the old one open. Theres a screen in there. You are looking for metal. If metal is in there then you will need to flush the system.

How is an AC system flushed?
TY

Bullitt347 · May 30, 2022

You can get a flush kit for A/C systems from most auto parts stores. It does require compressed air to do it correctly. They have a special solvent that gets flushed through the lines and evaporator/condenser. Don't think you can use it on the compressor itself.

93CalypsoConvert · May 30, 2022

I doubt its clogged. I can turn compressor by hand and hear it hissing through that area. The entire kit was brand new excluding the evaporator (which looked brand new). It was flushed before install anyways. Two contour fans wired to ac relay pulling 3000+ cfm through it. Also doubt its an airlfow problem... Should I go rent the manifold guages and check out whats going on?

Gs1987GT · May 30, 2022

I would if I were you, or just get them from Harbor Freight and be done.

7991LXnSHO · May 30, 2022

93CalypsoConvert said:
AC was working fine until one day I open my hood to find this seal blown, along with AC oil all over my battery. System still has a charge, but I haven't turned it back on since,

It sounds like the title should be “What seal just threw up?”
+1 to the gauges.

Mustang5L5 · May 30, 2022

That’s the overpressure blow off. You were probably a tad bit high on the high side. I think they blow at 500psi or more.

You really need a set of manifold gauges to see the pressures on both sides of the system. Usually an extremely high pressure on the high side is a sign of a blockage in the orifice tube, or poor airflow through the condenser. You can usually tell if it’s the latter by having manifold guages hooked up and splashing water on the condenser. If the pressure drops, you need to address condenser airflow. If it doesn’t, the orifice tube line needs to be replaced as it’s likely clogging.

There’s a few NOS ones on eBay for a reasonable price, or you can buy one that hasn’t been sitting on a shelf for 30 years from parts store. I'm honestly on the fence as to which is the right path because there is also a drier inside the line that can become saturated and require a DEEP, LONG vacuum pull to really get it moisture free. But, that can also happen to a brand new one at the parts store.

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I do not have a source for the overpressure relief valve for the 6P148A. If someone finds one let me know.

90sickfox · May 30, 2022

I have Contour fans too. They pull a ton of air.

93CalypsoConvert · Jun 12, 2022

I got around to checking it out. So everything still works great, and my pressures run about 25 low and 200 high. 41 degrees through the vents at cruising engine speed. I suppose not much Freon escaped if I'm still getting such great temps.

I do believe airflow seems to be an issue though. I have my contour fans set on a stand-alone controller with a +12v AC signal wire. When my compressor engages, fan #1 starts about 5 second later, then 10 seconds after that fan #2 starts. This is an intentional design to reduce load on charging/electrcial system.

The problem with this system is my high-side climbs FAST when there is no airflow. Especially when the engine is hot and sitting still. It gets in the upper 300s before the fans have enough time to lower the pressure. I imagine this is the point where my seal blew beforehand. I am going to work on fixing this and I will keep y'all updated.

manicmechanic007 · Jun 13, 2022

That popoff valve does blow at 550 lbs.
The cooling fan being inoperative is the usual suspect
Overcharged is the other
Sometimes if you are lucky and you overcharge the freon
It will blow some out and then be okay after that
Disconnect the cooling fan someday with the ac gauges on and watch the high side climb into the red zone real quick

What seal just blew up?

93CalypsoConvert

Active Member

90sickfox

Wasn't a pretty sight...and I've got big hands

limp

wrap a little cheese around it and its a done

Bullitt347

I have been doing it wrong this whole time

93CalypsoConvert

Active Member

Gs1987GT

Active Member

7991LXnSHO

wanna catch the space herp

Mustang5L5

That is…until I whipped out my Bissell

New Genuine OEM Motorcraft A/C Liquid Line For 1993 Mustang 5.0L V8 YF-2492 | eBay

90sickfox

Wasn't a pretty sight...and I've got big hands

93CalypsoConvert

Active Member

manicmechanic007

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What seal just blew up?

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That is…until I whipped out my Bissell

Wasn't a pretty sight...and I've got big hands

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