Hello,

I own a 77 F150 with a 351M engine. Recently I got the factory air conditioning going. There is a problem though, the compressor shakes badly when running. The belt looks like it is going to freak out it is vibrating so badly. This is mostly at idle. As the RPMs come up, the vibration seems to smooth out.

Is this typical of the old compressors on these trucks or am I missing some sort of strengthening bracket?

I have a bracket mounted to the left cylinder head that the compressor sits on top of, and a bracket that runs off of the right side of the compressor to the water pump area. Am I missing something?

Other than the vibration, the air blows cold and works well.

Thanks for your time and help,
John Thomas

 

I would check your bolts and your charge in the system. It should not vibrate the belt violently or the compressor. You are using the correct belt? I wonder if your system is overpressurized or has a blockage somewhere.