JakePSD
Well-Known Member
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I've got a 2017 GT PP. Just under 9k miles. I've had to have the A/C recharged once or twice before due to a refrigerant leak. At first I thought it was the evaporator core considering they had issues, however I noticed yesterday when attempting to recharge it myself that the high side port had a few bubbles in it when I removed the fitting. I mention that just to give everyone here an easy thing to check before assuming it's the evaporator.
Anyway, the real issue I'm having is that both the high and low side pressures are all over the place. With the engine off and the system equalized, the static pressure appears dead on (95-100 degrees ambient, 120 psi +/-5). Once started, A/C on max, engine at idle, low side is about 35-40 psi, high side about 240 psi. Air out of the vents drops to about 58 degrees.
Once I bring the RPMs up is when things go haywire. Around 2500 rpm, the low side drops to about 20 psi and the high side climbs to about 320, which I assume is normal. However, after about 10 seconds the low side and high side start fluctuating. Minimal at first, but continuously getting wider and wider fluctuations until the high side hits the roughly 475 psi cut out, at which point the compressor kicks off until the low side comes back to around 50 psi, then the process starts over. It also acts up at rpms as low as 1000, it just takes longer before it kicks out. It's really only steady at idle.
Anyone have any ideas? I'm thinking maybe a faulty expansion valve, but I'm not sure if these cars have that, or an orifice tube, or even the weird valve system they used on the mid to late 2000s Taurus. Or maybe it could be a faulty sensor throwing things off? I have Auto Engineuity so I can look at all the sensors if I knew what I was looking for.
EDIT: Here is a video of what's going on. It's a bit lengthy (about 16 minutes). Watching the whole thing isn't necessary, it's long because I show what it does at various RPM.
Anyway, the real issue I'm having is that both the high and low side pressures are all over the place. With the engine off and the system equalized, the static pressure appears dead on (95-100 degrees ambient, 120 psi +/-5). Once started, A/C on max, engine at idle, low side is about 35-40 psi, high side about 240 psi. Air out of the vents drops to about 58 degrees.
Once I bring the RPMs up is when things go haywire. Around 2500 rpm, the low side drops to about 20 psi and the high side climbs to about 320, which I assume is normal. However, after about 10 seconds the low side and high side start fluctuating. Minimal at first, but continuously getting wider and wider fluctuations until the high side hits the roughly 475 psi cut out, at which point the compressor kicks off until the low side comes back to around 50 psi, then the process starts over. It also acts up at rpms as low as 1000, it just takes longer before it kicks out. It's really only steady at idle.
Anyone have any ideas? I'm thinking maybe a faulty expansion valve, but I'm not sure if these cars have that, or an orifice tube, or even the weird valve system they used on the mid to late 2000s Taurus. Or maybe it could be a faulty sensor throwing things off? I have Auto Engineuity so I can look at all the sensors if I knew what I was looking for.
EDIT: Here is a video of what's going on. It's a bit lengthy (about 16 minutes). Watching the whole thing isn't necessary, it's long because I show what it does at various RPM.
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