Losing Refrigerant rapidly on my 98 Mustang GT

TekoSn95 · Jun 21, 2025

Hey guys hopefully I'm not posting this in the wrong forum section but hopefully I am

I recently just installed a new AC compressor into my 98 Mustang GT made sure everything was plugged in and the line connections at the compressor we tightened up though now I do run into an issue. I am rapidly losing refrigerant. I took the car to AutoZone just yesterday bought a small can of refrigerant and the AC started to get cold but when I stopped somewhere else for about 11 or so minutes and came back to the car my AC was running warm again and the compressor was short cycling. So what could be my issue? I do notice some green dye around the low side Schrader valve so that could be my issue but I do want to ask here as well should I re check the lines that connect to my AC compressor? I can add pictures if needed

Mustang5L5 · Jun 24, 2025

Sounds like you have a leak, which needs to be repaired. I would look around elsewhere for signs of leaking dye.

If you pull a vacuum on the system? Does it hold that vac for an hour or two?

TekoSn95 · Jun 24, 2025

Hey Mike.

When I did first run a vacuum on the system to remove moisture it held that vac for an hour or two but throughout the day I had to keep removing and putting on the guage system from the low side and high side AC ports. Though I believe at one point I mightve put too much pressure down on the low side pipe possibly cracking it at the valve stems base because there's a tiny bit of liquid pooled up at the base of the low side valve stem. I did look in other areas but there wasnt any signs of leaks as far as I saw (My AC Compressor did come with new seals for the compressor to line connection). So for right now I just bought another low side pipe assembly and im planning on replacing the pipe today and when its finally done getting installed im gonna run another vacuum

nickyb · Jun 24, 2025

How did you pull too much vaccum? If your gauges read 28-30 inches and hold it when you shut the pump then your golden.

TekoSn95 · Jun 24, 2025

nickyb said:
How did you pull too much vaccum? If your gauges read 28-30 inches and hold it when you shut the pump then your golden.

I should've explained when I put the gauge connection on the low side pipe it was hard to get the connection on so I put physical pressure on the pipe to get the connection on. the gauges read at 28-30 inches when I pulled a vacuum and it did hold when I shut the pump off but when I finished running a vacuum. I had a can of refrigerant that I thought I could throw into the system (it wasnt that much refrigerant but enough to let the compressor clutch kick on). I then went out to AutoZone got a bigger can and I guess when I put pressure on the low pressure side connection again I mightve cracked the pipe at the base of that connection (if this doesnt make sense I can attach a photo of what I mean).

Mustang5L5 · Jun 24, 2025

Sounds to me like you might be right with the crack on the low side line, but I can't see it for myself.

When you go to pull vac, best to let it run overnight you can. If not, the longer, the better. Really these systems need to pull down to 500-1000 microns, which is 29.88 inHg. 29.00inHG is about 23000 microns, which is ok, but not really ideal for AC work. Most gauges on the manifolds don't have that sort of resulution....so the more time you can vacuum, the better.

TekoSn95 · Jun 24, 2025

Mustang5L5 said:
Sounds to me like you might be right with the crack on the low side line, but I can't see it for myself.

When you go to pull vac, best to let it run overnight you can. If not, the longer, the better. Really these systems need to pull down to 500-1000 microns, which is 29.88 inHg. 29.00inHG is about 23000 microns, which is ok, but not really ideal for AC work. Most gauges on the manifolds don't have that sort of resulution....so the more time you can vacuum, the better.

Yeah ill do that!

Just got the new line in so im ready to put it in the car and hopefully have cold AC again!

nickyb · Jun 24, 2025

Good luck,and let us know.

TekoSn95 · Aug 17, 2025

nickyb said:
Good luck,and let us know.

Well I shouldve made this post earlier but thankfully a friend of mine caught it before I did anything else he has a 97 GT and he recently replaced his valve stems on his hoses and he told me despite it looking like the valve stem is apart of the line it does come off and can be replaced for cheap. So I did have a leak from my low side but just around the valve stem which saved me a ton of money and time. Car runs cool again and im proud of it though there are other issues I need to work out with it but right now im happy with it

Losing Refrigerant rapidly on my 98 Mustang GT

TekoSn95

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Mustang5L5

That is…until I whipped out my Bissell

TekoSn95

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nickyb

I gotta say i never painted my nuts, Never Ever

TekoSn95

Member

Mustang5L5

That is…until I whipped out my Bissell

TekoSn95

Member

nickyb

I gotta say i never painted my nuts, Never Ever

TekoSn95

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