jstrdn90rs

I just installed a brand new ac delco compressor and when I turn it on it vibrates ...I made sure all the bracket bolts were tight.I was wondering if anybody else has experienced this and what they did to correct it?.Is it possible since its new that the internal components have little clearance?

bingo

iTrader: (2)

Did you pour oil in it before charging the system? The compressor could need more oil added.

jstrdn90rs

Yea..I poured about 8 oz in the lines then a few more inthe compressor before I bolted it up,and spun the compressor by hand a few times.I was thinking the same didnt have enough,but the problem is this is an R-12 system and I have no idea how I am going to get more oil in it.I have a bottle of mineral oil,but getting it in the system without losing freon is the trick.

DragRacer383

iTrader: (2)

you don't need more oil if you have over 8oz. The system calls for 6oz.

Stephen

iTrader: (12)

I just did mine a couple of weeks ago. 134a.

Same thing....When the AC is on, My center console vibrates, and gives off a "humming" noise. At this point, I'm just gonna live with it. Only happens at idle. Like stopped. Once I give it a liitle gas, the vibes stop immediately.

jstrdn90rs

Stephen ..that is exactly what mine does..humms at an idle gets a little louder when I take off,but gets quiet when I hit cruisin speed.I figure I would just live with it too..I was considering maybe putting some brass washers in between the compressor and the bracket to see if it would help or something similar?..Otherwise I am hoping its just cause its new.

Stephen

iTrader: (12)

Lemme know if the brass helps out. You gonna machine the bracket or compressor for room to fit the washers?

marlow

is your fan coming on?

Stephen

iTrader: (12)

Both fans work fine. As long as the compressor isn't "compressing", there are no vibes.

jstrdn90rs

Yes..I only have a single fan,and its working....car actually cools better with ac on.Thats the next project dumping that fan for a shroud fan..just got a see if I can find a donor.

Stephen

iTrader: (12)

If you want, 6" of wires, a wire tap, and a ground loop under the relay, will get that fan running whenever the key is on.

jstrdn90rs

I would do that ,but I dont want to burn up the fan motor..running all the time.It needs a break once in while.That stock set up is kinda cheap...doesnt have any shroud to really move some air when its on.Plus,I think it sits far from the radiator which doesnt help either.

Stephen

iTrader: (12)

Did it my 92 RS, then my wifes 90 RS. Neither fan never died.

In the winter, I would pull that ground loop lose, so the heater would heat up quicker for the drive to work.

You might wanna consider upgrading to the dual fan set up on TPI cars.

sogabe

are you all sure that the vibration
isnt due to worn motor mounts?

when ac is on, means engine is in a heavy load,
so when your motor(or even trans mount) is weak,
it could possibly cause ur engine to vibrate.

its normal for an engine to vibrate more when a/c is on,
its just that when your mount isn't worn out,
it will still be stable.


if ur mounts are new and fine.. excuse my wrong guess
but I think that could be it though.
happens in older cars not just camaros,
my friend's sentra(96) had same problem
and it was the motor mounts.
I never had thsi problem caz my mounts are new..

hopefuly this was a help. good luck

Stephen

iTrader: (12)

I suppose that COULD be a problem with some cars.

But, in my case...AC off, no vibes..at all.

AC...Vibes...

Definately AC related, no doubt.

jstrdn90rs

I was considering the mounts too..I cant really get a good look at them even in daylight..I am sure they are original and wouldnt hurt to change them.

sogabe

your a/c compressor itself vibrates?
or the whole engine vibrates?

worn mounts can cause vibration only during heavyload,
such as when a/c is on,
so its very common that car is very stable until a/c is on
just so u know

i think the left motor mount is very easy to visually inspect,
use a flashlight and look from engine bay or from buttom of car,
and see if the rubber part looks cracked or worned out.

if u never replaced them,
i bet they wont look that good as our generation car is aged at least 14years.

jstrdn90rs

[quote=sogabe]your a/c compressor itself vibrates?
or the whole engine vibrates?

My compressor vibrates only ..when its off can't feel a thing..its more of a humming noise then a vibration.I was thinking earlier today that its possible the mounts are sagging and sitting on metal.

jstrdn90rs

I had a similar problem on my grand am and it had a growling noise until I added oil to it and it when away..thats why I was thinking I didnt have enough oil in it.It had all new mounts including the trans and a dog bone.So I am kinda lost on this one ,I dont have the specs for the oil so I cannot say I have enough or not enough oil in it.

suh_wheat_86305

iTrader: (1)

Howdy,
I just bought an 86 ta, 305 tpi. The old man who sold was the orignial owner and took very good care of it. He recent replaced the ac compressor and other required parts. As noted, it too has a humming vibration at idle... some might compare the sound to a coffee grinder. I notice that if I leave the car in drive, put on the parking brake, get out and pop the hood that the ac belt is singing away and the whole compressor is blurred by the vibration. I also see from the old man's notes that this is the second compressor install in the last 10,000 miles.
Any thoughts on this... anyone?
Or... Do you, or anyone else, know of a better ac compressor, like a caddillac?

Stephen

iTrader: (12)

That's odd. Mine (87 GTA) is missing the front mounting bolt (threads stripped), and it doesn't hum at all, even missing a bolt.

It sounds like the PAG oil wasn't put in. I just can't stop the console vibrating. No biggie. I had forgotten about, as I've gotten used to it, until I read this thread.

Joelkatdaddy

Make sure you have the correct charge in it. If you're sucking back liquid in the compressor it will vibrate and amkes lots of noise. Also, too much oil is a bad thing and not enough is just as bad.
Joel

jstrdn90rs

Well...my system is still running R-12 as I have many older mechanic friends,but since I started to use the ac once in awhile ,it doesnt vibrate as much as it used too.I think it was just due to a new compressor (tight clearances).Yes,I have the correct amount of mineral oil in it.I turned it on a few months back to check and make sure it gets cold,so I will have some time to fix it before it gets too hot if it didnt and I couldnt even tell it was on ,but it was.I think it has a lot to do to the age of the compressor and how much the compressor is working.Motor mounts would probably help ,but havent replaced those yet.

suh_wheat_86305

iTrader: (1)

another comment...

my 86 305 tpi AC vibrates like hell at idle, then immediately silences as soon as the rpms are above ~900... like I described in an earlier post, and like others have described.

I might just set the idle at 1000 when the AC is on...not quite sure how to do that, but a little research should get me there... unless anyone would like to tell me...!!

Silver87

Yeah, mine had that problem too. You could see the belt flopping even though it was tight when the A/C kicked on. I found a bolt missing at the rear of the compressor. I replaced it to find the noise still there. I solved my problem by raising the idle speed of the idle solenoid on the side of my carb. If it goes below 700 RPM it starts vibrating and the belt starts flopping. My oil and refrigerant charge are fine and I'm on the original compressor.

gmendoza

iTrader: (1)

Okay, all I've seen here are bandaid repairs. What is the cause of a vibrating/humming AC compressor at idle (below 800 rpms) and how do you fix it? My GTA is doing the same. It blows could but hums like crazy!!

gmendoza

iTrader: (1)

I found the fix. Turns out the brackets were loose and the belts were old and loose also. It's quiet now.

186irocz

When converting to 134 you have to replace the accumulator, the filter dryer<--- and flush the system, 134 does not mix with the mineral oil and will ruin your compressor and eventualy cause your compresor to blow, mine did. I replaced everything and then put the 134 in and its awsome, no vibrations and it blows ice cold. The retro kits tell u just to vac the sys down and charge with 134, this is totaly wrong! It must be flushed and the filter dryer must! be replaced! the oil makes the sys have way 2 much pressure in it!

jstrdn90rs

I used brass washers behind the bolt heads on the AC/PS bracket and it seem to quiet it down more then it was...I just put them behind the bolt heads not in between the bracket and engine..I had installed a new water pump ,tensioner,and belt and still vibrated..I had a new compressor installed and since then as its broken in, I dont hear it that much.Used be like a growling dog at idle...

Stephen

iTrader: (12)

Yeah, when I put on my new AC compressor,actually my local club did it, on a Car Fix Day for me. But whenever the AC was turned on, my shifter handle rattled/vibrate like a handful of pennies, on a 18" subwoofer, powered by 500 watts! After a running it a few times=, the vibrations went away.

Badazz85TA

I replaced my AC compressor a couple of years ago and converted to 134 and i still have that vibration problem at idle.
so when it happens, i just pop the car into neutral, raise the rpms to 900, and it's smooth.
in the past i adjusted the idler screw so the vibrations would stop. it worked for the summer, but during the winter when i didn't use the AC the car would idle too high and be a B***h to drive in bumper-to-bumper traffic.
but i was wondering if there's a way to raise the idle only when the AC is on through programming the chip in the computer.
i don't know much about PROM, the ecm and all, but does anyone know if it's possible?

jakemussman

iTrader: (3)

Yes that is possible. You can set how many RPM's to add when A/C is turned on.

88fastform

iTrader: (1)

My 88 Formula has new mounts, tried 2 compressors, did the tsb to reroute the belt, new tensioner, and installed the bracket that goes from the back of the compressor to the intake (88 didn't have that for some reason). All that did help but its still there driving me crazy. The only area I can feel it under the hood is the AC hose from the compressor to the condenser. Should these cars have come with a muffler or something there? Maybe the condenser mounts grounding out? Surely as many of these cars as there are, someone has fixed this.

evilemokid94

iTrader: (6)

My 86 does it, only noticeable at idle

actarnoff

iTrader: (1)

My factory compressor does this. I am almost positive it's because of the extra load on the motor when the AC clutch engages.

85 ZXX

iTrader: (1)

I replaced everything and it still vibrates at idle. At 900+ RPM's it does a little better though.. I have the v-groove belt setup on my 85 TPI. I wonder if a Sanden compressor would work on our cars?