AC compressor noise

[3TT3V]

Finally I got my LT-4 engine from a totalled 96 Corvette installed in my S10 Xtreme and I can say Wow, what an engine! Now for my question: When I am at highway speed and the AC compressor cycles in; there is a droan or a groan sound coming from the AC compressor.
Is that common?
Is it about to take a crap?
What can be done to alleviate the droan or groan noise?

 

[3TT3V]

additional info: makes droaning noise at 2100+ RPM when AC cycles in....sorta seems like a balance problem. Anybody?

 

[Vettelt193]

It could just be a vibration, did you use S-10 AC, or the AC that came with the LT4? this could simply be a loose bolt, or a mounting issue.

 

[3TT3V]

Used Vette LT 4 Compressor, Custom condensor for fitment, and S10 evaporator.

 

[Vettelt193]

you retained the factory bracket and location of the compressor?

 

[3TT3V]

yes, had purchased Corvette LT 4 engine with all belt driven accessories already attached

 

[Vettelt193]

ok... that tosses theory 1 (assuming all the bolts are tight)

the next idea is the AC clutch isn't engaging properly. Will it make noise if you are simply hitting higher RPM's? you can test it by leaving it in 1st, and speeding up until the rpm's are above 2000, then turn on the AC, same noise? It may be happening on the highway because the engine is at a constant higher RPM. If the clutch is not engaging right, it may not be able to fully engage the AC, which could definitely cause a droan.

 

[3TT3V]

The droaning is at RPM 2100 thru 2350 only/ any gear. Bolts are all tight/ new belt.

 

[lt4george]

I had the exact same vibration at 2100/2200 rpm. It is the ac brackets. There was 3 original support arms bolted to the
stock exhaust manifolds. When I had the long tube headers installed, the installer did not/could not reinstall any
brackets. Thats when my vibration started. I came up with a
spacer and longer bolts and attach one bracket to the headers
and got rid of 90% of vibration. I plan on working on it
till I get rid of all the vibration.

 

[3TT3V]

LT4George.....can you please post picture of your bracket/mounting for AC compressor LT4 w/ headers.

 

[3TT3V]

I finally fixed it ! As LT4George said...I got the 2 braces, utilized a spacer due to header usage, and now no more vibration. Gee, it only took me over a year to accomplish that !!! What next!!! Thanks to all.