Blue Bowtie........Thank You

Make sure the compressor has all the necessary braces. Several GM models have had compressor "groan" or "howl" due to inadequate bracing, resulting in the compressor vibrating on its mounts and creating a harmonic noise. If you can start the engine and SAFELY work around the compresor with it running, you might try to loosen a mounting bolt or two and see if the noise changes. That would be an indication of a mounting issue. Early Astro vans with the 262 V-6 suffered from this, and had a factory add-on reinforcement brace as a solution. Early 1980's F-Cars with V-8s had a similar problem, and also required a factory add-on bracket to solve the issue. You might want to check the mounting bolts for the entire accessory mount bracket to make sure they are tight, too.

Today I replaced the valve seals & was checking the A/C brackets as you advised. I had a bolt loose that was hid behind the lower pulley on the passenger side. This fixed my compressor-growling problem!!! (see thread “Installing New A/C Compressor In A 91... Which Brand To Buy??“). I couldn't believe it. Everything I had tried to do to fix this & comes down to one loose bolt. I've had the truck for 6 years & have been listening to the transmission downshift thru the groaning – growling of the a/c compressor all this time. I'll have to go to therapy for help. I'm not sure if I can take all the quietness.

I was about to spend $300 plus to re-do the system again. You saved me a lot of time & money & I thank you!!

Willie

No need to thank me. Each of us has different experiences and abilities, and we're all here to learn, share, and help wherever we can. Members represent a broad range of fields, from professional technicians with formal training to enthusiasts with decades of experiences, members with an intuitive ability to analyze problems logically, and others with experiences in non-automotive technical, manufacturing, service, and professional fields. Even those with less experience can be helpful, since opinions without preconceptions or bias can frequently provide a fresh prognosis to a problem. Each has a unique perspective and may have experiences which may not be covered in textbooks. Where I live, I've found that this kind of diversity creates powers well beyond what any singular idea or philosophy can ever yield.

You can show appreciation by helping make this a better place for all participants. When you see a member with a question or problem, and you have advice or experiences which might be relevant, feel free to offer your assistance.

lol my experience is just in the "what not to do" category, such as, dont try to warm your engine up faster in the winter by driving around in first gear, or you will have serious wear and tear issues... that was the death of my first 350 lol, when i was 16, i was an idiot, what can i say