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Aloha~ all Ac working but noise from compressor when AC not engaged stops when engaged 160,000 miles any thoughts? thanks
 

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can you describe the noise? or, post a recording with audio?

I also find those $5 mechanic's stethoscopes SUPER useful for isolating noises. In particular I've used them to identify wheel bearings and idler pulley bearings, they make a grinding noise when you use the stethoscope.
That said, I'm not sure a bearing would explain what you've got here.

odd that the noise goes away when it's engaged. I've never heard of this, but just thinking logically, what if the clutch is somehow scraping when the a/c is off and then when it locks up when you turn the a/c on, the noise would go away? (I'm just thinking through and making up a theory). Other than the clutch, I can't think of any other part that could STOP making noise when the a/c is engaged. wouldn't be bearings. wouldn't be the belt.

also just noticed your greeting, 'aloha.' would you happen to live on Oahu?
I'm here in Aiea :D with a yr 2000 toyota sienna xle, 121,000 on the odometer.

my own a/c has been behaving strangely, but it turns out I can replace pretty much the entire a/c system for $500 if I do the work myself. compressor, condenser, drier, relay, triswitch, and both hoses, and $100 for an evac/recharge. NOT doing the evaporators (there are two, front and rear), without definite cause those are just so much work to get to.

so rather than chasing waterfalls trying to diagnose it, I'm just replacing everything. a terrible habit (parts swapping) but i figure with everything being 20 years old and original, I'll come out ahead by just doing it all.
I did the same thing last year when I opted to just do all the cooling hoses and radiator, when one hose started leaking. I don't trust 20 yr old rubber haha.
 

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Discussion Starter #3
can you describe the noise? or, post a recording with audio?

I also find those $5 mechanic's stethoscopes SUPER useful for isolating noises. In particular I've used them to identify wheel bearings and idler pulley bearings, they make a grinding noise when you use the stethoscope.
That said, I'm not sure a bearing would explain what you've got here.

odd that the noise goes away when it's engaged. I've never heard of this, but just thinking logically, what if the clutch is somehow scraping when the a/c is off and then when it locks up when you turn the a/c on, the noise would go away? (I'm just thinking through and making up a theory). Other than the clutch, I can't think of any other part that could STOP making noise when the a/c is engaged. wouldn't be bearings. wouldn't be the belt.

also just noticed your greeting, 'aloha.' would you happen to live on Oahu?
I'm here in Aiea :D with a yr 2000 toyota sienna xle, 121,000 on the odometer.

my own a/c has been behaving strangely, but it turns out I can replace pretty much the entire a/c system for $500 if I do the work myself. compressor, condenser, drier, relay, triswitch, and both hoses, and $100 for an evac/recharge. NOT doing the evaporators (there are two, front and rear), without definite cause those are just so much work to get to.

so rather than chasing waterfalls trying to diagnose it, I'm just replacing everything. a terrible habit (parts swapping) but i figure with everything being 20 years old and original, I'll come out ahead by just doing it all.
I did the same thing last year when I opted to just do all the cooling hoses and radiator, when one hose started leaking. I don't trust 20 yr old rubber haha.
Aloha we are on the Big Island I don’t think I would replace every thing! Could be the evaporator! The front one is easy to change or check for leaks. Now my ac is loosing charge after a month can’t find the source figuring it is in the rear evap or the lines under the van I bought a block off kit but way to hard to reach up and behind engine I will have to cut off line upfront under the vehicle then I can pull it up after unhooking it from the front evaporator block it off they say there’s plenty a seat to run up front and in the van apparently you don’t need a rear evaporator. Back to the noiseMore like a high-pitched sound I’ll have to get one of those stethoscopes! I do have a call into my friend Son n Law who has a machine shop in California about the noise I think I’m just rambling on brain doesn’t work as good as it used to I have replaced a lot of stuff on the car so could let you know stuff good luck with ac remember easy to check for leaks in Evaporator in front! Ray
 

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Aloha we are on the Big Island I don’t think I would replace every thing! Could be the evaporator! The front one is easy to change or check for leaks. Now my ac is loosing charge after a month can’t find the source figuring it is in the rear evap or the lines under the van I bought a block off kit but way to hard to reach up and behind engine I will have to cut off line upfront under the vehicle then I can pull it up after unhooking it from the front evaporator block it off they say there’s plenty a seat to run up front and in the van apparently you don’t need a rear evaporator. Back to the noiseMore like a high-pitched sound I’ll have to get one of those stethoscopes! I do have a call into my friend Son n Law who has a machine shop in California about the noise I think I’m just rambling on brain doesn’t work as good as it used to I have replaced a lot of stuff on the car so could let you know stuff good luck with ac remember easy to check for leaks in Evaporator in front! Ray
I'm interested actually: can you link the block-off? I NEVER use the rear a/c, like ever, haha.
as a confession, I haven't actually looked up the procedure. I just remember the evaporator is crazy hard to get to on any other car I've seen (deep in the dash, inside the climate control box: like 8 hours to remove pretty much the whole dash to get it out). is it... is it actually easy on the sienna? If it is, I'll swap it.

The condenser is the one in front of the radiator that's always easy to get to, the evaporator is the one on the inside usually in the climate control box. Please let me know if it's actually an easy job on my 2000 sienna, I'll order one!

you can always do the blacklight and dye, it might help find leaks.
 

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I'm interested actually: can you link the block-off? I NEVER use the rear a/c, like ever, haha.
as a confession, I haven't actually looked up the procedure. I just remember the evaporator is crazy hard to get to on any other car I've seen (deep in the dash, inside the climate control box: like 8 hours to remove pretty much the whole dash to get it out). is it... is it actually easy on the sienna? If it is, I'll swap it.

The condenser is the one in front of the radiator that's always easy to get to, the evaporator is the one on the inside usually in the climate control box. Please let me know if it's actually an easy job on my 2000 sienna, I'll order one!

you can always do the blacklight and dye, it might help find leaks.
Hello again a lot of cars you have to pull the whole darn dash out not so on an older Toyota sienna easy job! Took me about an hour and a half. I did use the green dye with the light could not find a leak just a very small amount in the back evaporator and a sniffer picked up something under the car but not definitive if I remember why I got them block off kit from Amazon it runs about 80 bucks which I think is a little ridiculous they don’t tell you how hard it is to get to it on the back where the two lines fasten together on the low side the high side!
 

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Hello again a lot of cars you have to pull the whole darn dash out not so on an older Toyota sienna easy job! Took me about an hour and a half. I did use the green dye with the light could not find a leak just a very small amount in the back evaporator and a sniffer picked up something under the car but not definitive if I remember why I got them block off kit from Amazon it runs about 80 bucks which I think is a little ridiculous they don’t tell you how hard it is to get to it on the back where the two lines fasten together on the low side the high side!
Sorry the high side is easy to block off!
 
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