nvu

If it's the old school manual air, check the pressure sensor. It's somewhere on the condenser high line. Short it and see. The temperature sensor is some feedback transistor, you can't short it to test. Unlikely as it only cuts out when the temp is too cold. Unlikely the AC switch itself is bad, you can bypass it and force AC on by turning to full defrost. No idea where to begin with the auto climate control, never had to deal with one.

If it's the single gauge one on the low side only. Yes it would read high, around 80-90psi when the system is off. Not much else to add about why it's not kicking on, but it's normal to see it high on a single gauge reading. Thinking it's more electrical than a system problem. Did you swap the relay with a similar one on the car yet?

Not sure, haven't had one break on me. Quick search on the internet seems like idosubaru has been through it before. He's on this forum too... https://www.subaruoutback.org/threads/repairing-captive-nut-failure-lots-of-complications.151202/

Swap in the used pair, it's less hassle. But also measure the length of the front bushing on your car and confirm first. The swaybar mounting tab may be different too, make a note of it. Figure out if you want to get those Delphi bushings and build a spare set later. Also pray to the rust gods that the big bolts don't break the captive nuts in the frame when you try and remove them. If it's the original bushing on the car, chances are the nut inside is corroded, I'd recommend completely relieving pressure on the arm by removing the knuckle before breaking loose bushing bolts.

oh right, if it's 2.5 electric throttle. the tps is in there but not easily replaceable, you have to adjust the set screw for it and have an ecu data reader. though, i've never heard of a tps failing on those style of throttles. they either completely fail with the motor not working or make a terrible grinding noises if the gears are sheared. the tps part is pretty reliable

2005 nonturbo should be cable throttle, it should be on the opposite end of the where the cable throttle goes and replaceable.

Odd, it should not kick off from charging at all for these models. There's no ecu control if it's 2 wire so no way to tell it to power off. Do you think there's a corroded wire in the harness causing intermittent charging? If you have a spare connector, dash lightbulb, and a switch, you could make a dongle from the alternator to the battery + and manually force the alternator on to test.

It should work. Only models I know need all 3 pins on the alternator were the sti and XT models with the 32bit ecu, electronic throttle. If yours is cable throttle, it's the old style and only uses 2 of the 3 pins.

I went reverse, 2006 alternator in 98 impreza. Swapped from black rectangle to green oval plugs and works fine. Though 13.5-14v at the battery is kinda of standard nowadays, it's okay for newer batteries.

If there's air, theres a leak. Check the lines for wetness and under the clutch reservoir. Get a scredriver and depress the slave piston in so you can wiggle the clutch fork back and forth. It should only move in two directions. If it's flopping all over the place, somethings broken, bearing, fork, pivot pin.

Other places to check. If near the rear passenger, check the pcv hoses. If turbo, theres a middle block nipple that likes to leak when the clamps weaken from heat.

I don't know for sure but suspect eyesight equipped vehicles need this step. I heard it's a nightmare to replace windshield glass with an eyesight system and it needs some special alignment and setup again. Not something any windshield shop can do.

I vaguely remember a youtube video about having to hook a computer up to the car and set something before installing the brakes. I'll see if I can find it again...

Try steering with the fill cap off and see if tiny bubbles apear. If so, likely the S shaped hose from the reservoir to the pump has gone brittle and sucking in air at the pump nipple.

There's a module you unplug to turn off the DRL permanently. On an 02 impreza it's passenger side glovebox/footwell area near the fuel pump relay. It's probably the same area on your legacy. Download the service manual for your car and find out.

as a test you can just skip it all together and short the connector pins together. the compressor should kick on. its function is pretty basic, too high or too low pressure it'll switch off. it'll short the pins when the pressure is nominal.

it's likely fine, the timing chain tensioner can get sticky, but doesn't fail catastrophically like the timing belt tensioners. those years had the oil consumption issues due to low tension rings from the factory. probably check if your model year is affected and keep an eye on oil levels between changes

oil filter up top is an fb engine, timing chain. they're noisy on startup until the tensioner fills with oil. no need to replace if it doesnt sound bad when warmed up

Check if the cabin heater working. If so the pump is working. Might still be some air trapped in it, try parking at the steepest incline you can and do the radiator fill again.

I only see one wire tapped from the main harness. can you trace blue/pink wire and see if it runs into the ignition switch? guessing it's a breathalyzer module that needs breathing into to start the car.

The suspension gains positive camber really quickly when it's near the end of its travel. Not sure what's causing your too high issue, but the vibrations are likely from the tires gaining positive camber when the suspension bounces up higher than usual.

As long as it doesn't leak it's fine. They are tapered threads so likely the new one has more meat on it and sits higher. Is the 2010 an EJ engine? If so don't worry about cracking the block. The oil galley has a nut with a tapered hole for the sensor. Worst case you only need to replace that nut if the sensor threads get ruined. Random picture, but you see the nut where the pressure switch goes on to.

Likely as a failsafe. If the charge bulb burns out, the alternator would stop charging and there wouldn't be any other way to know until the battery's drained.

The brake indicator is also connected to the alternator. If it's going off and you're sure it's not the fluid/parking switches, the alternator is grounding itself. Either it's bad or there's a short somewhere.

Just occurred to me there's an intake air temp sensor on the maf. The codes are pointing at the maf, did they clear after you plugged it abck in and reset the ecu? On my 2003 impreza, I've had the maf heater wire cook itself brittle before. Cut open the wiring loom and see if any individual wires have discolored. With my case, the car never threw any codes, but the plastic tab was broken off for a while. Only found it after splicing in a new pigtail, the burnt area was about 6" before where there was a cable tie on the loom.