Climate Control Rattling Sound

I've heard many a noisy HVACs in Gen2 Prius... I've avoided working on them thus far, just turn it off and say, "I fixed it," which has always worked for me. Never gets more problematic than that. At least yet.

PS: I enjoy watching your YouTube videos about living in a Prius!

 

tough to hear, but an odd sound. maybe a vent door struggling to open or close, maybe something in the fan, have you checked it?
can you determine approximately where it is coming from?

 

You got to try and narrow that down whether it's in the center of the dash over towards the fan unit on the passenger side upwards of that is the intake filter and what have you

 

By "turned on" you mean the fan is spinning and not when the fan is not spinning?

Assuming yes...

Does it make that sound when neither the AC nor the heat should be active (fan only)?
Does the sound change when the fan speed changes?
Change the air flow direction (down to feet, out the vents, to the front window) does it change? Does the sound pause or shift while the system is moving the control door?
Open the hood and listen there (when the ICE is not running), is the sound coming from the front of the engine compartment?
Is the air intake behind the hood obstructed in any way? (Packed with leaves, a piece of paper stuck in it? Use a flashlight.)
Pull out the cabin air filter, does it still make that sound?
Block the path (briefly!) where the air filter was (with something solid like a board or whatever you have), does it go away?
Pull out the glove box and put your ear next to the blower (or touch it with the tip of a screwdriver and put your ear on the handle for a poor man's stethoscope), is that where the sound is coming from?

 

Since the frequency of the noise goes up with the blower speed it will either be a problem with the blower itself, something rubbing on it, or something loose in the air stream oscillating at an air speed dependent rate. I suppose we can't rule out the mechanism for the door which controls the air direction.

Did anybody do work under your dash before this started? If one of the tubes was not fastened correctly it could be rhythmically bumping.

This isn't likely, but air outlet vents in cars can sometimes oscillate. If you cover each of them with a cloth (like a T shirt which has been folded over 4 times) it will block the flow and would stop that noise at the problem vent.

 

it's easy to pull off the glove box door and pull the filter out to check for debris in the fan.
if it's a vent door, that can be more complicated

 

Yeah once you start down this path and you can't do any of the work yourself you are getting backed into a serious corner here this is New Jersey man isn't it isn't it starting to get cold up there in the evening Gawd danged. My wife will be trying to run that shit when it's 40° outside It's just really something You sure other things aren't happening that need to be checked out I remember living in New Jersey in New York about time September hits most folks usually weren't running the air conditioner but now that climate change is eating us alive I imagine this pushes that until almost October up there now but usually you're not sitting in the '70s and whatnot at night this time of year what maybe it's possible. And then what happens when it gets really cold?

 

Okay you keep saying nothing coming out does that mean the fans not blowing or your temperature controlled air isn't coming out at temperature We need to get where we need to get with the discussion so we know what's happening. So you have fan on all speeds you just don't have the conditioned air at any speed of the blower or the system any of it when you're doing this are you in the recirculate mode your temperature is on l o on the screen not on 75 or something We don't want to do that we're trying to get air conditioning because you're introducing warm stuff from the hot side of the system a big no-no in my world when you're trying to get air conditioning but some people.? If blower is going in and out what you want to do is just reach your hand under the glove box You don't have to really do a lot of bending and stooping and see if the bottom of the fan motor is excessively hot like almost a fry an egg on then I would think you've got problems with the blower motor and you need to get something with newer windings and that sort of thing The blower motor maybe drawing too much current and getting overly hot because you don't have codes do you have a bunch of lights on the dash red triangle etc then there may be no codes If your fan motor is going bad I don't think the system has a code for the fan motor not sure the compressor yes so again if the system is on and the hood is up and you're touching the fat and skinny silver hoses the skinny silver hose should be the heat coming out of your cabin and going to the condenser which is the thing in front of the radiator. And the other fatter line that's marked l for low pressure that should be cold like a refrigerator cold well not really the refrigerator is 37° this pipe is going to be between 45 and 50 something then you're making cold If you're not getting it in the car that is another issue with blower motors clogged airways or something.

 

If there's anything about the noise that varies in proportion to the fan speed, that'd be a sign to look for something fan-related. If the noise seems to vary in proportion to the compressor speed, that'd be a sign to look for something compressor-related.

I haven't listened to your recording, but you might take a moment yourself to listen to the one in this link, just to make sure it isn't that. That's a known issue that can be expected in elderly gen 1 or 2 Prii.

No, that wasn't a mouse in the heater | PriusChat

 

if you can get a new compressor for one fifty, i'd go for it

 

are you still running a/c in september?

 

If the blower makes odd noises and sometimes doesn't run then it is almost certainly going to be at the blower. (Electrical problems to it are perhaps possible but would be, I think, very unlikely.) If you get lucky it might be some piece of whatever that got in there and is interfering with the rotation, and that can be pulled out. More likely the blower is just going out.

So I reiterate, try pulling out the cabin air filter. If the wrong filter is in there, or it is damaged, or leaves are packed up under it, it could interfere with the blower. Here is an example in a Prius V, for the impatient, skip to around 5:20

 

You got debris in same location as your cabin air filter... Easy to fix. Clean it out and replace cabin air filter.

 

i just turn of my hearing aids