Loud humming noise from air conditioner

Under some load conditions, it's normal for the compressor to cycle on and off.

How long have you had the car?

Have you asked for diagnostics from the HVAC system? (Hold the fresh/recirc and auto buttons while turning the car on, then watch for 2-digit codes at the top left of the MFD screen.)

 

the compressors are noisy to begin with. especially with the hood up. the faster they run, the noisier they are.
if the sound is increasing, it could mean it's on its way out

 

just one possibility. it's an expensive fix, so you want a competent diagnosis.

 

idk, you can look at the service manual, or perhaps someone else knows

 

It's worth mentioning we've got a wiki page where Elektroingenieur kindly put together lots of information on getting access to the Repair Manual and other tech info, both through Toyota's inexpensive online subscription or through other options like a local library where you may have access for free.

I think the HVAC two-digit codes xy just directly correspond to DTCs B14xy (the blink codes for some other things in the car are not always so tidy, and have to be looked up in tables to find the corresponding DTCs).

So those are B1433, B1442, and B1443. Interesting, but probably not to do with the compressor hum. 33 and 43 are both about the servo that controls which air outlets you have selected (43 is an electrical issue detected with that motor, and 33 is about the sensor that detects its current position). 42 is the same kind of thing, but for the servo that controls the air inlet (fresh or recirculate).

Those would be worth tracking down eventually, but maybe they aren't your chief concern right now if you're worried about the compressor.

But there's also the dog that didn't bark: you don't have any codes there about the compressor. That doesn't always mean there isn't one, but it can be a good reason to think about how sure you are that there is.

 

did it improve after the refill?
could be a leak? did you have it filled at a toyota dealership, or qualified prius shoppe?

 

is it the cooling fans on the radiator?

maybe not a fan at all, you've got several pumps in there. coolants, brakes, etc.

 

I had this problem and traced it to one of the radiator fan motors. I replaced the radiator fan assembly and the problem went away.

 

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No its an indica

If you had the refrigerant refilled last week that means you have a leak. If it was empty it didn't evaporate. You didn't use one of those Auto parts store fill er up cans did you? I assume so because if an AC shop did it they would have put dye in and found the leak.
Be aware operating the compressor with low refrigerant is very bad for that very expensive compressor.

If you think you have a noisey fan take the black plastic cover off the top of the rad. You can then look down and see both fans. The compressor is low on the passenger side. In Max AC mode both fans should be running. Helps to have a flashlight. See which one is loud.

Don't see alot of rad fan issues on a G2. Can't remember a post about one. Unlike alot of other cars. Mine are going on 14 years old still OK.

 

What was the cost? Did you DIY?

 

One of my radiator fans is kind of rumble-y recently. I haven't cared enough so far to grab a stethoscope and figure out which one. Hmm, maybe I'll go do that now....

Edit: stethoscope says my rumble-y one is the right one, a/k/a the one with the blue wire, a/k/a the "cooling fan". Not the left, green-wired, "no.2 cooling fan". (At least Toyota moved away from the previous-generations naming, where one was the "radiator fan" and one the "condenser fan" even though they were both equally behind the radiator and condenser.)

Edit again: ok, weirder, in the Repair Manual diagrams, the right fan is the "no. 2 cooling fan". Looks like the wiring diagram and repair manual disagree as to who is "fan" and who is "no. 2 fan".