Weird clicking noise at idle, and no A/C?

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E

eeetwentyone

Joined
Jun 5, 2025
Threads
2
Messages
10
Location
Albuquerque, New Mexico
Hi all, I have owned my 2004 LX470 for about 8 months now. It has 220k miles, and has been an absolute pleasure to drive! I have put about 10k miles on it so far myself.

It has started acting up with two issues that I am not sure how to diagnose. I am reasonably mechanically competent, but am not familiar with the LC100 platform yet. I am hoping to understand whether these issues are something I can tackle with 3-4 hours on a Saturday morning, or if I should just budget to take into my local LC shop.

Issue 1: When at idle, in drive, and cold... I can hear a pretty loud clicking noise. It sounds almost like the radiator fan is hitting something. This noise goes away when I either shift into neutral/reverse/park, start driving, or if the car is fully warmed up and it is a warmer day. I attached a video where you can clearly hear the clicking, and then it goes away when I shift to neutral. I first noticed this last November when it started getting chilly (under 50 degrees f), though it continues to happen most mornings. Maybe unrelated, but I have a driveline clunk that I occasionally hear when starting from a standstill, or when getting back on the gas after coasting. I feel like I can associate hearing the clunk with the noise, but I haven't put together the pattern yet.

Issue 2: It seems my AC has gone out. When I turn on the AC, the rpm surges, and the AC light begins to flash, and then eventually the AC shuts off. I have attached a video of this process, expect it didn't surge when I decided to video it (typical). At times, this surging is significant enough to get the rpm low enough for the battery voltage light to flutter. When driving, the rpm doesn't surge, but the ac light flashes anyway and it shuts off shortly after. Any common culprits?

Thanks all!

Clicking noise video:
AC issue video:
 
eeetwentyone said:
Issue 1: When at idle, in drive, and cold... I can hear a pretty loud clicking noise. It sounds almost like the radiator fan is hitting something. This noise goes away when I either shift into neutral/reverse/park, start driving, or if the car is fully warmed up and it is a warmer day.
Click to expand...
I was hoping to pop in here and give you some quick advice on how to diagnose accessory belt / idler noise BUT man that sounds different....The big clue you are giving is that when you shift out of gear, the noise changes and when temperature changes you have different symptoms
>>> If I were you I'd want to make sure my transmission fluid is where it should and there are no leaks... Do a search around the forums to find info on this.
>> I'm not sure if the 2004 LX has a dipstick or not, hopefully someone more knowledgeable can chime in

It doesn't sound belt, idler, fan related.....


If you wanted to eliminate a few possible suspects, you could remove your serpentine belt and then do the same test. If the noise goes away ( hopefully it does )
then you problem is related to something that is being spun by that belt...

If the noise doesn't go away , then you know its not related to any of your belt driven accessories and will have to dive deeper.
 
Last edited:
eeetwentyone said:
Issue 2: It seems my AC has gone out. When I turn on the AC, the rpm surges, and the AC light begins to flash, and then eventually the AC shuts off. I have attached a video of this process, expect it didn't surge when I decided to video it (typical). At times, this surging is significant enough to get the rpm low enough for the battery voltage light to flutter. When driving, the rpm doesn't surge, but the ac light flashes anyway and it shuts off shortly after. Any common culprits?
Click to expand...
I wonder if your two issues are related....I don't think so but we'll see....

I have never had that issue but I've definitely seen many forum posts about it. Try searching around . You probably are low on refrigerant so the compressor is engaging, and then disengaging ....Just my guess.

You could pop the hood and look down at the AC to confirm but based on your RPMS it appears the AC engages and then gives up.

-----
If I were you the next things I would do are:
- Figure out how to check transmission fluid
- Pop my hood and visually inspect belt for too loose / too tight / tension problems
- Remove my accessory belt and spin all components, focusing on the AC and making sure it spins freely
- Start engine , put in drive, and see if noise symptoms change per your first issue
 
Mike NXP said:
I was hoping to pop in here and give you some quick advice on how to diagnose accessory belt / idler noise BUT man that sounds different....The big clue you are giving is that when you shift out of gear, the noise changes and when temperature changes you have different symptoms
>>> If I were you I'd want to make sure my transmission fluid is where it should and there are no leaks... Do a search around the forums to find info on this.
>> I'm not sure if the 2004 LX has a dipstick or not, hopefully someone more knowledgeable can chime in

It doesn't sound belt, idler, fan related.....


If you wanted to eliminate a few possible suspects, you could remove your serpentine belt and then do the same test. If the noise goes away ( hopefully it does )
then you problem is related to something that is being spun by that belt...

If the noise doesn't go away , then you know its not related to any of your belt driven accessories and will have to dive deeper.
Click to expand...
Mike NXP said:
I wonder if your two issues are related....I don't think so but we'll see....

I have never had that issue but I've definitely seen many forum posts about it. Try searching around . You probably are low on refrigerant so the compressor is engaging, and then disengaging ....Just my guess.

You could pop the hood and look down at the AC to confirm but based on your RPMS it appears the AC engages and then gives up.

-----
If I were you the next things I would do are:
- Figure out how to check transmission fluid
- Pop my hood and visually inspect belt for too loose / too tight / tension problems
- Remove my accessory belt and spin all components, focusing on the AC and making sure it spins freely
- Start engine , put in drive, and see if noise symptoms change per your first issue
Click to expand...
The noise never appears at startup weirdly enough. But I can usually get it to act up within a few minutes of leaving the house at the first red-light. Is it safe to drive it for 10-15 minutes with the serpentine belt gone? Looks like the water pump isn't on that loop so probably fine? At a bare minimum I can pop the belt off and give everything a spin sometime this week to see.

Transmission fluid should be okay, as I had it drained and refilled by the dealer last Summer when baselining the truck. I suppose they could have done it wrong though. Symptoms did not start until much later though. Pretty sure the 5 speed in the 04 does not have a dipstick, but I can poke around.
 
eeetwentyone said:
The noise never appears at startup weirdly enough. But I can usually get it to act up within a few minutes of leaving the house at the first red-light. Is it safe to drive it for 10-15 minutes with the serpentine belt gone? Looks like the water pump isn't on that loop so probably fine? At a bare minimum I can pop the belt off and give everything a spin sometime this week to see.

Transmission fluid should be okay, as I had it drained and refilled by the dealer last Summer when baselining the truck. I suppose they could have done it wrong though. Symptoms did not start until much later though. Pretty sure the 5 speed in the 04 does not have a dipstick, but I can poke around.
Click to expand...
If you remove your accessory belt you won't have alternator charge ( or power steering ) . Probably don't want to drive too far, the goal with the removal was to help narrow down your problem. Wait until the problem happens, then park, remove belt, and re-test to see if problem goes away.

Water pump is internal and your timing belt keeps that turning
---
hopefully transmission service was done properly at the dealer, but maybe its worth asking them if they can re-check and not charge you a fortune to do so.
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I listened to the video again, you should be able to narrow it down a bit more since that's a pretty loud knocking noise....I wonder if its something simple like your engine cover rattling around....

you need a second set of hands to assist....Get the problem to happen again, pop the hood, and just look / listen / touch carefully around to try and feel those vibrations....Touch top of engine, go down below put hand on transmission...

I don't know, just trying to think of simple / free things you can do to narrow it down
 
Its crazy how it just goes away completely when you put it into neutral, that's got to be a clue....

If you put it in drive, and that noise is happening, and then you try to drive, what happens? does it drive smooth? Sorry if you mentioned this earlier...
 
Mike NXP said:
Its crazy how it just goes away completely when you put it into neutral, that's got to be a clue....

If you put it in drive, and that noise is happening, and then you try to drive, what happens? does it drive smooth? Sorry if you mentioned this earlier...
Click to expand...
It is crazy. I was thinking that it might have to do with load on the engine. When it's in drive, there is a torque applied against the engine from the (stopped) driveshaft. When in neutral, that load goes away. That made me think that maybe motor mounts could be shot, and the whole engine is rocking a bit, making the fan click against something.

But that theory falls apart because there is no clicking under hard acceleration, which also applies that same torque to the engine.

If it is clicking away and I try to drive, the noise goes away almost as soon as I let off the brake, and by the time I reach 3ish mph at the latest. It drives just fine at that point.
 
eeetwentyone said:
It is crazy. I was thinking that it might have to do with load on the engine. When it's in drive, there is a torque applied against the engine from the (stopped) driveshaft. When in neutral, that load goes away. That made me think that maybe motor mounts could be shot, and the whole engine is rocking a bit, making the fan click against something.

But that theory falls apart because there is no clicking under hard acceleration, which also applies that same torque to the engine.

If it is clicking away and I try to drive, the noise goes away almost as soon as I let off the brake, and by the time I reach 3ish mph at the latest. It drives just fine at that point.
Click to expand...
Your motor mount theory can be tested easily and in my experience I do not think your noise is caused by bad motor mounts. You would have other symptoms .
>> If you want to test motor mounts, pop hood, put car in drive with foot firmly on brake, have someone stand next to hood and observe while you tap the throttle quickly. If mounts are bad you will see motor move / clunk and know right away

I do not think your fan is clicking against something , its hard to tell in video but honestly it sounds like some heavy knocking going on, not so much of a clicking
>> Again this theory can easily be tested, get someone to look under hood while the problem is happening ( carefully ) and look at the fan and everything spinning up there. Maybe something obvious will stick out . usually if one of the spinny parts is failing you would hear it at idle and being in drive shouldn't matter

>>Interesting, so if the problem is happening and then you just drive off, its smooth driving / no knocking / issues to note....We probably have to conclude motor/transmission/drive shafts/ all that is fine or else the knocking would keep happening

IDK dude, maybe I'm missing something obvious here or could be totally off but this is a doozie..

Start back with the simple stuff and try to narrow it down. The problem is consistent enough when you could get someone to look under hood for stuff that might be to blame.
 
Oh, what about exhaust rattle? Heat shield / weighted thing hanging off muffler / mounts / and all that stuff....Usually more of a tingy / metal like noise but idk it would add up for a few of the symptoms you have...

Can drop down underneath on passenger side and shine a light up and along the exhaust route to see if its all rotted out or anything obvious....Check the weight that hangs off the muffler under passenger side rear door....
 
Mike NXP said:
Oh, what about exhaust rattle? Heat shield / weighted thing hanging off muffler / mounts / and all that stuff....Usually more of a tingy / metal like noise but idk it would add up for a few of the symptoms you have...

Can drop down underneath on passenger side and shine a light up and along the exhaust route to see if its all rotted out or anything obvious....Check the weight that hangs off the muffler under passenger side rear door....
Click to expand...
Oh that's an interesting idea! It does have a similar sound as my old Xterra had when an exhaust heat shield was loose... just louder this time.


Mike NXP said:
Your motor mount theory can be tested easily and in my experience I do not think your noise is caused by bad motor mounts. You would have other symptoms .
>> If you want to test motor mounts, pop hood, put car in drive with foot firmly on brake, have someone stand next to hood and observe while you tap the throttle quickly. If mounts are bad you will see motor move / clunk and know right away

I do not think your fan is clicking against something , its hard to tell in video but honestly it sounds like some heavy knocking going on, not so much of a clicking
>> Again this theory can easily be tested, get someone to look under hood while the problem is happening ( carefully ) and look at the fan and everything spinning up there. Maybe something obvious will stick out . usually if one of the spinny parts is failing you would hear it at idle and being in drive shouldn't matter

>>Interesting, so if the problem is happening and then you just drive off, its smooth driving / no knocking / issues to note....We probably have to conclude motor/transmission/drive shafts/ all that is fine or else the knocking would keep happening

IDK dude, maybe I'm missing something obvious here or could be totally off but this is a doozie..

Start back with the simple stuff and try to narrow it down. The problem is consistent enough when you could get someone to look under hood for stuff that might be to blame.
Click to expand...
I appreciate the help! It sounds like I have some homework to do, and will report back with observations. Assuming work plays nice, I should get to it in the next day or two.
 
eeetwentyone said:
Oh that's an interesting idea! It does have a similar sound as my old Xterra had when an exhaust heat shield was loose... just louder this time.



I appreciate the help! It sounds like I have some homework to do, and will report back with observations. Assuming work plays nice, I should get to it in the next day or two.
Click to expand...
For sure, with such a heavy / consistent noise if you could get someone else to run around under vehicle / hood I bet you could feel around and narrow down a bunch.

good luck
 
Could be the compressor clutch, if it it’s repairable.
 
My AC did the same thing once, had someone watch it when I turned the compressor on and noticed the magnetic clutch wasn't engaging. It had backed out just far enough it couldn't pull it in. Just needed to push it in manually and haven't had an issue since.
 
Convinced my wife to help me out and did some digging around. I think my AC compressor is seized up? It looks like the clutch engages, but it can't actually turn the compressor. There is a video below of what it looks like when the AC is turned on. I also tried to spin it by hand. The pulley spins freely (maybe ever so slightly crunch), but I can't turn the compressor itself. Should I be able to spin it though?




For the weird clicking noise... I feel stupid. I had my wife shift back and forth from drive to neutral to see if we could replicate the issue. I found a hose that had escaped its hose clip, and the hose clip was rattling around. I clipped that back, and it "seems" like that might have been it, as I couldn't recreate the sound after clipping that hose. Still a mystery as to why it only seems to act up in drive... while parked... when cold. If I hear it again tomorrow morning on my drive to work I will report back.

youtu.be

Potentially the mysterious clicking noise???

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The hose that escaped its clip pictured above.
 
Didn’t hear the clicking noise again. I did hear a much quieter “buzz” sound in the same conditions, but not reliably (happened in maybe 1 out of 5 stops?). I think that issue is generally solved. I feel stupid but it is what it is.

Ordered a denso ac compressor and ac desiccant this morning. Looks like the job shouldn’t be too bad. Anything else I should do while in the area?
 
eeetwentyone said:
Didn’t hear the clicking noise again. I did hear a much quieter “buzz” sound in the same conditions, but not reliably (happened in maybe 1 out of 5 stops?). I think that issue is generally solved. I feel stupid but it is what it is.

Ordered a denso ac compressor and ac desiccant this morning. Looks like the job shouldn’t be too bad. Anything else I should do while in the area?
Click to expand...
Nice find on the noise....Im still not much help on your AC issues, I'm not sure if it should free spin easily or not with belt off. I think it should? Sounds like you are going to swap it...Do a search around for a good replacement forum on MUD
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As for your noise, totally, when motor is cold, put into gear , RPMS change, vibrations change, and that big flexy engine cover was probably slapping around...You should consider removing it one day and just getting it all cleaned up and re-secured....maybe nuts are loose, maybe the foam underneath is all disinegrated....I like to keep mine in place though, serves a purpose and holds that vac line in place.... some just get rid of it.
----

The buzzing you are hearing, most likely your brake system...You could / should hear it when you first turn your key to the on position, before starting...Then, throughout driving you will hear it doing its thing now and then......That would be a quick easy thing to check, its under your hood on driver side, against the firewall....Make sure fluid is clean and up to level...make sure you read the reservoir for instruction on procedure on how to check ( pump brake 40 times first )
 
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