high RPM vibration when A/C is on only

[ls1frc]

Hey all, have a vibration going on. Feels like when you drive over rumble strips on the road. I thought something in my driveline was ******, so I started poking around at the u-joints, the flywheel, and the TC. Everything looked good.

I went to test today and miraculously it was not doing it. It was 65 out, so I was driving with my windows down. Started to get a little hot, so I put the A/C on and noticed it started doing it again. I'd go WOT and it feels like the tires are gonna fly off. Hit the A/C button, immediately goes away...

Truck has 152k on it. A/C blows ice cold, no issues. Is this just a bad A/C compressor? Potentially something with the front pulley? Crank pulley only has 5k miles on it.

Something with the A/C bracket maybe?

 

[Geotrash]

Have you observed the A/C pulley in operation to see if the vibration is evident visually?

Here's my worry, and I hate to raise it without knowing more about the symptoms: The compressor may be locking up. If so, it will cause the belt tensioner bounce. Once it locks up, the belt will break and it will be a PITA to clean and flush the system.

I had it happen on an ex-GF's Honda CR-V once and I about junked the car.

 

[ls1frc]

Have you observed the A/C pulley in operation to see if the vibration is evident visually?

Here's my worry, and I hate to raise it without knowing more about the symptoms: The compressor may be locking up. If so, it will cause the belt tensioner bounce. Once it locks up, the belt will break and it will be a PITA to clean and flush the system.

I had it happen on an ex-GF's Honda CR-V once and I about junked the car.

It does sound like something is locking up because I can hold it at 4000 rpms and the vibration will stop after about 3 seconds every single time. So it's like it struggles to keep up but then frees itself.


You know I did a ton of engine work to this thing, so I was fearing the absolute WORST haha. I was having nightmares about separating the trans on jack stands to replace a flexplate.

I'll poke around and check the bracket tomorrow, maybe I will get lucky.

 

[thompsoj22]

Is it possible it is overserviced with either refrigerant or oil. Either one of these will cause the compressor to "slug" or "hydraulic lock". It is a brutal ratcheting sound when it happens and will fubar your compressor and fill your entire ac system with metal debris if allowed to continue. Our vehicles are prone to this ailment because the compressor is the lowest mounted component in the system so excess lubricating oil or extremely overserviced refrigerant in liquid state will gather here and the compressor does not like to pump liquid. It will destroy it.

 

[ls1frc]

AFAIK, it is still in factory condition. Never touched by anyone.

 

[Foggy]

AC compressor has a "stretch to fit" belt, so no tensioner....
I would suspect a compressor going bad...
See if you can have someone bring the rpms up and cycle the compressor
as you visually watch whats going on ...
Do it from the bottom with the plastic 'skid plate' off and you'll be able
to see it really well
As mentioned , don't wait till it totally blows before replacing.. it'll be hard to
clean out all the debris.