Sudden noise while environmental controls are on

I have a 2024 Prius Prime with about 30k miles. Yesterday as I was pulling up the drive, I suddenly heard a very loud buzzing noise coming from the engine compartment. The change was drastic enough that I immediately stopped in the drive and my passengers asked "What is that?!?" I was in EV mode at the time, so I crept forward into the garage and shut everything down.

I had never heard anything like this prior, so I started searching the web and I think I found a video which captures the sound accurately here. Unfortunately, only the first 2-3 seconds of the video has the sound. In my case, it stayed on until I shut the car off. I can try to take a sound recording if there is interest.

After doing a bit more reading, I wanted to try to see if I could isolate it a bit by turning various functions on and off. I was able to determine that the noise went away if I turned off the environmental controls. As soon as I press the "Auto" button, the buzzing noise returned. My guess is it's the heat pump compressor as it's definitely coming from the engine compartment and not the cabin blower fan.

So now my question for this esteemed group: Is this compressor also part of the liquid cooling for the EV system or is it only for environmental control? I'm trying to determine if I can still drive it until I can get it in the shop or if I need to park it due to the chance for additional damage.

 

I was afraid of that. I have not had the car on long enough for it to display an error code. In fact, I haven't checked to see whether the A/C still cools, so I don't know if it's completely dead or just starting to fail. Do you think it's safe if I run it in ICE (HV) mode?

 

I'll call my dealer on Monday and see what they say. I'm hoping it's a semi-uneventful fix. In either case, I'll record what happens here for future users.

 

Following up, today I took the car in to the local dealer for evaluation. As I feared, the compressor is in need of replacement. According to the service manager, replacement cost is $8100. I got the impression that this was parts only, but it could be that this included labor. Fortunately, this is covered by the 3 year/36k mile warranty. They said they ordered 1 of only 2 that were currently available and scheduled the fix for Aug 5th.

I asked if there were any concerns with me driving the car while the compressor has failed and they said "Just use the A/C sparingly." I pressed a bit further asking that since it was also responsible for cooling the battery, should I only use HV mode? They didn't think it would be an issue. It reaches into the upper 80's and 90's this time of year and I have my doubts. I think I'll only use HV mode to be on the safe side.

Lastly, I asked to have them check their Toyota rep if this part is covered under the longer power train warranty or even the battery warranty rather than just the bumper-to-bumper warranty. Hopefully they have a response when I return on the 5th. Otherwise, the replacement part only has a 1 year/12k mile warranty.