Ford Super Duty (1999-2016) :: A/C Compressing With Good Pressure But No Cold?

My a/c compressor crapped out a summer or two ago. I ordered a new compressor and dryer, oiled up the compressor properly, hooked it all up, vacuumed out the system, filled it with fresh 134a and it worked just fine for about a year. Mid-late last summer, the a/c quit working, so I hooked up my gauges to check it out.

Everything reads in the proper range. The high side is only about 150, which isn't stellar, but not terrible either - certainly enough to cool things down. Anyways, when I was sitting at idle checking things out, my compressor was running all the time and not cycling on or off. Given that I was not overcharged (according to my HF gauges), I tried to add a little more to it. It would only take half a bottle and the compressor never started cycling on/off, so I stopped tinkering with it for a while to think on it. I noticed that when I had it on driving in town, I could hear the a/c kick on and off every couple seconds like it was still low, but my gauges didn't indicate that it was low and it wasn't taking a charge like it was low. This whole time, the air from the vents is not even cool - just straight outside air temp and the lines don't feel cold either.

I had hot-wired my compressor to stay on and same story. The gauges show it's compressing with the low side right where it's supposed to be and the high side a tad low at idle, but easily jumping up to within spec with mild revs. The whole time, the vents and a/c lines are no colder than ambient.