Automotive Air Conditioning Information Forum

I'm working on my granddaughters AC which was very low on refrigerant (2002 Ford Taurus). The car had been sitting a couple years after her other grandfather passed away and she just turn 16 and starting to drive it. I took a gauge reading and there appeared to be little or no refrigerant, so I pulled a vacuum for about 45 mins and then sealed the system. I let it sit for about 1 1/2 hours and didn't see any drop. I started charging the system but it would only take about 6 oz. My low side gage show 80lbs and the high side was 0. The compressor had not kicked in. I shut the car off and closed off the refrigerant to the gauges. I opened the high side and they gauges balance at about 60lbs static. I know it only has about 6oz at this point. I closed the high side and started the car and opened the refrigerant again. It slowly took a little more refrigerant and the compressor started. My low side did not fall but raised to about 80Lbs again. The high side went to about 175 for maybe 30 seconds and then continued to climb. It put in another 12oz for a total of 18oz of refrigerant (system holds 28) and it wouldn't take any more. The low side pressure increased to 110lbs and the high side climbed to high cutoff at approx 375 where the compressor shut off and the cooling fans went to high. The high pressure dropped to approx 125lbs and the compressor kick back on taking it to about 200lbs. The low side never moved from 110lbs. The compressor cycled 3 or 4 time with pressures on high side turning the compressor on at 125Lbs and cutting of at 200lbs. Then the compressor remained on until it reached 375lbs and the high cutoff shut the compressor off and the fans would go to high. It continued to cycle the same way until I shut if off. I've repaired a few ac systems over the years but have never ran into something like this, but I'm not a professional. Any thoughts? It almost seems I have more than one issue.

Is your Manifold Gauge Set hooked up correctly while charging--that is, low-side handwheel fully open, high-side handwheel fully closed, both adapter thumbwheels fully open (turned clockwise until they stop); yellow hose connected to the refrigerant source, and refrigerant-source valve fully open?

I have amended this response

1. How did you "seal the system?"
2, Gauge readings of 70-80 only represent a static reading, without any work being done, even if the comp is running. If the comp is running and all else is OK, meaning metering device and all, the the low has to come down. If you put gauges on a refrigerant container to only see what psi is in the can, at this time of year you will get 70-80
3. "I opened the high side and they gauges balance at about 60lbs static. " By opening the hi side knob you allowed the hi side gauge to read the system FROM the hi side and also that pressure was mixed with whatever the low side was doing, so it is not a true representation of what is going on. I am not sure of this statement since it is not clear which handwheels are open.
With the service handwheels shut, the gauges always read directly into the system, you do not have to open any handwheels.
Again, it is not clear here if both handwheels were open for some of his readings.

I think we are gonna have to dissect this one step at a time, and first we need to know how you did the sealing.

tbirdtbird wrote: ↑Mon Aug 02, 2021 10:51 am I think we are gonna have to dissect this one step at a time, and first we need to know how you did the sealing.

I could be mistaken, but I believe the OP meant that he closed both handwheels on the Manifold Gauge Set for 1-1/2 hours to see whether the vacuum would hold, which apparently it did.

His post is lengthy, so I think you're correct in dissecting this scenario one step at a time.

When I see the word "sealed" or "sealer" I worry...

with 18 oz in and the comp running I would expect the low to drop, not increase...you already know what I am thinking.....

Unless my reading comprehension is shot.....

Bad schrader valve / service connection. Evacuated the hoses and manifold only.

The clue is the "high side 0" The high side is never zero, unless it is not depressing the schrader valve.

later on he says the hi side went to 375

he is all over the map