AC crapped out. Going to DIY, thoughts?

[PSI]

On Sunday I discovered that my AC suddenly isn’t working. After a bit of troubleshooting, I found that the compressor clutch immediately disengages after receiving a call for AC.
According to Forscan, there are no codes present, and the PIDs related to AC show nothing unusual, with the exception of the fact that the one that tells if the ECU has commanded AC shows “NO”, though this is after the clutch has already disengaged.

I hooked up the manifold gauges I had from when I put in my mini-split, and took a static reading after the car had not been running for a good half hour or more. 180 PSI on the low side, and 290 on the high side. After sitting overnight the pressures do equalize to about 200ish. From my understanding the pressures should equalize fairly quickly, and also they are way too high anyway for the ambient temps with R134a.
When I did get the compressor to kick on after sitting overnight, high side shot up to 400+ and compressor kicked off.

My suspicion is there is a blockage, but that doesn’t explain the overall high pressures. I am the second owner, so possibly the AC had been previously serviced and overcharged? Air in the system? I did notice that when the low side cap was removed there was a pretty good bit of pressure under it and also green dyed refrigerant oil in the Schrader valve. Could it be pulling in air from there?

Give me your thoughts guys.

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[ORRadtech]

Model year?
Those pressures are way, way high which is probably what is kicking the compressor off.
My first WAG is a blocked expansion valve (or whatever Ford uses as one). The problem is if something is blocked you're either going to have to replace a lot of parts or hope you can flush the system. Of course that doesn't really give you the cause of the blockage so it could all happen again if you can't find the source.

 

[PSI]

It’s a 2016.
Sounds reasonable to me that everything needs to be gone through if a blockage is the case.
Looking at Rockauto they’ve got all the parts to change everything for a reasonable price. I know some would balk at replacing with non-Motorcraft, but considering the reputation of the AC systems in these cars, how much worse could it get?

For 303 bucks I can replace all but the lines and the evaporator, plus the cost of adding refrigerant back in. The condenser has a built in drier. I’m not sure if replacing the compressor would be necessary though, unless it is coming apart. That said, I’d be in there disconnecting everything anyway, so what is 3 more fasteners and a belt?
Gonna check around the evaporator drain with a UV light later when it’s darker and see if there’s anything glowing. I sure as hell hope not, I don’t want to have to rip the dash out!

Thanks for the input

 

[Garfy]

Model year?
Those pressures are way, way high which is probably what is kicking the compressor off.
My first WAG is a blocked expansion valve (or whatever Ford uses as one). The problem is if something is blocked you're either going to have to replace a lot of parts or hope you can flush the system. Of course that doesn't really give you the cause of the blockage so it could all happen again if you can't find the source.

Frankly, I don't think it's a "blockage" issue as he stated that after pressures equalize, both are reading at 200 psi, which is way too high for ambient pressures. Without the compressor running, pressure should be around 120-140 depending upon ambient temperatures. Once the compressor kicks in, the low side would drop to around 35-40 and high no more than 250. How his system got such high pressures after it had been working "normally" for so long is curious. BTW, there is no way any air or anything gets into his system via the service ports, since the system pressure is higher than atmospheric.

 

[mindo389]

Before I spent any money, I'd recover the refrigerant, evacuate the system and recharge it. Then see what happens.

 

[PSI]

Quick follow up:
Borrowed the unit to recover refrigerant, a tank, and a scale. I ran the recovery operation and only got out 3/4 of a pound. Hood sticker calls for 1.5 pounds. Verified there is no pressure left in the system, at least at each Schrader valve.
I pulled a vacuum on it for approximately a half hour, and I’m currently watching for decay on the gauges. Will continue vacuuming more if there is no noticeable decay.

 

[PSI]

Well it held vacuum so I went ahead and charged it to see what would happen. Refrigerant is pretty cheap, it only takes 2 12 oz cans.
It is ice cold now, 80 degrees outside and the car is in the sun, with outlet temps on the dash reading in the 30s. Everything seems perfectly normal now.
I have no idea what caused this in the first place, I’ve had the car for 4 years with no issues. I guess we’ll see if it holds. The only experience I have with refrigeration is installing my mini split in the house, so it’s good experience I guess.
Thanks for the help guys.

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