Need Help AC Compressor on/off

[TexasHD]

So here is a rundown my ac is hasn't been cold for the last few days so i crawl under the truck to check if the compressor is coming on. The compressor kicks on for about 5 seconds and shuts off for about 15 seconds then back on etc. I hooked up a gauge to the freon port and the needle would spike then fall. Also when i removed the cap off of the freon port there was pressure and some green stuff was all over the port. So is the compressor going out? PS its still hot here in South Texas

[drunk on diesel]

you're low on refrigerant. probably the schrader valve leaking. Mine's been giving me hell this year since we did the thermostats on the truck. I've replaced the valve once.

About to put a Ford one in there. Hoping it's higher quality than the parts store one I put in prior, but I have a sinking feeling they're made by the same manufacturer LOL

[TexasHD]

when the compressor kicks on the gauge says its within range but like i said its only for a second ill ad some freon tomorrow how do you remove the schrader valve ?