2005 Subaru Outback XT AT running too hot when going up hill

As the title says, my OBXT is running way too hot when heading up hill. Recently have had the caps and cooling system pressure tested and all passed. I had the head gasket replaced, water pump, timing belt, pulleys, etc. The engine was also pressure tested and passed.
The Subaru techs and I are at a loss.
Any ideas?

Replace the radiator cap anyway.

A thermostat replacement might help, as it may not be opening all the way. Some shops can check radiator temps at different points on the radiator to see if a blockage might be occurring. In the olden days before spring reinforced radiator hoses sometimes the pump could exceed the capacity of the lower radiator hose and cause it to collapse, limiting fluid flow.

It may be normal for your car, is there a red range it goes into, or temps you can quantify?

How many miles on the car? Does it have to be heading uphill? How about on the highway at a steady 75 MPH. Any trouble then? If all else fails, a new radiator is next…

Radiator fans operating as they should?
Make any difference with the A/C on or off?

Has a radiator flow test occurred or new radiator?

I agree with the others here. If the cooling fans are working as they should be then replace the radiator as the next step in the process.

I’ll have to check the radiator. Head gasket was recently replaced. I performed a hydrocarbon test and it came out clean. The temperature issue has always bothered me on this car. It’s been an issue since we purchased it (new) but now it’s much worse. My 2006 Legacy GT runs like a dream, no overheating issues at all, and it’s the car I take to the track. The only major difference is that it has a manual transmission.

I originally asked about the cooling fans and their operation with the A/C on or off, etc.

If the radiator turns out not to be the cause and the fans are operating as they should be, you might consider the possibility of partially clogged converters.