belt noise
 

Hello All,

V2500 5.7.

I installed an onboard air system from littleshopmfg. It is a york 210. Prior to the install my engine/belt system was as expected. The ac would kick on and the usual noise would accompany it.

Now, with the second pump and a longer belt I get a horrible hum/vibration somewhere when the OE AC comes on. I can not see or hear anything under the hood but when in the cab it is that low rumble and resonates. Like when you can hear a subwoofer from a car 50ft away at a stop light.

Any ideas? Belt to tight? too loose? The tensioner feels right

https://www.littleshopmfg.com/gm-4-3...ompressor-kit/

Re: belt noise
 

Should have said the harmonics are only at idle, Once on the gas it goes away.

Re: belt noise
 

Re: belt noise
 

It appears the noise is coming from the compressor. This is the last R4 compressor i will ever deal with. The first two failed in less than a month, the 3rd lasted a year and this 4th compressor lasted 4 years. It is undercharged so not to run too much head pressure but I think even thought they are listed to run 134a they just can't deal with the pressures.

I am going to install a sanden, buy brackets, make hoses and hopefully be done with it for the last time.

Chris

Re: belt noise
 

I would look at the mounting of the York.

Re: belt noise
 

Still have t he noise, Update,

Still chasing this horrrible sound. Went to the AC shop and they said exhaust, exhaust shop said motor mounts, Anyway, I have installed new motor mounts, cut off the exhaust and installed new and replace the R$ with another AC delco R4 and the sound is as bad or worse.

the tensioner, idler, belt, PS pump are all new. The water and alt are 3 years old and show no signs of failure. Today i will remove the york OBA completely and if htat does not fix it I will do the alternator tomorrow.

I will try to take a video of the noise in the event someone stumbles across this thread with the same issue in the future..

Re: belt noise
 

My low mile 86 suburban makes this same noise/rumble at idle as well with the ac on. I’ll be interested to see what you find out. My engine is 100% stock, so I’m not sure what is going on

Re: belt noise
 

I use a piece of heater hose as a stethoscope to listen for where weird noises are coming from.

Re: belt noise
 

Is the AC idle compensation circuit working? On an old carb setup, there was a simple solenoid that bumped the idle speed up when the AC comp came on. Without that, some motors would start vibrating a lot because they were idling too slow, or they would simply die.

Fuel injection setups should have a similar feature even if implemented differently.

Re: belt noise
 

I have a TBI,, it adds IAC steps when there is a call for AC

Re: belt noise
 

I found the issue after ~1000 of wasted $$ and time.

I removed the OBA compressor from LittleshopMFG and presto, noise gone. york210 is new and the fabricate nice brackets but something is a miss. Everything was perfectly aligned and when i call for OBA it works perfect. When the engine is running and not calling for AC it is perfect. Only when it called for AC and running a ~111" belt around the York OBA did it create the harmonics.

Crazy enough,, under the hood, everything sounded smooth,,, no noise, no vibration but apparently harmonics and acoustics are fickle. Like the drone of my 40 series flowmaster on a different build.

I am kicking myself for not taking it off sooner. I am confident when i contact LittleshopMFG they will have "never heard of it" and "never had an issue".

The clutch on the york appears perfect and spins freely so i do not know if getting another would make a difference. I doubt any of it is returnable.

I hope this thread saves someone in the future.

Chris