Rumbling A/C

[Mastiff]

This is just sort of a general maintenance thing, but I'm noticing that the truck sort of rumbles/vibrates intermittently when the A/C is on. Looking under the hood with it running I can't tell the exact source due to all the other noise. I just got it charged and have been using it for one season (didn't need it in Iowa). It may have been doing this all along.

The one thing I did notice is that the drive belt to the compressor vibrates quite noticeably when the A/C is on, so that may be my source. The belt is tensioned very tight. The guy at the A/C shop said to do that, so I snugged it up. Can a belt vibrate from being too tight? Any other thoughts?

 

[rjfguitar]

Your A/C pump is on it's way out. The reason why the belt is flapping so much, even when very tight, is because the pump is becoming very difficult to turn putting a lot of load on the belt. That is what belts do when they are maxed out load wise. When a pump is making that grumbly, rumbly sound, or a super fast "tick" that sounds like a tiny machine gun, it usually means the pump is getting ready to toss in the towel.

If I were you, I'd pull the pump off now and also pull out the orifice tube. If there isn't much for metal shavings caught in the orifice, contamination shouldn't be too bad. If you let it go until the pump locks up, I'd suggest replacing the condensor and evap. Once a pump scatters it's innerds throughout the system, it's very difficult to get every shaving back out.

 

[Blue85]

My compressor has been grumbling for like the last 7 summers. I keep thinking it's going to grenade, but I've had cold air.

 

[4xcrazy]

Mine grumbled & rumbled when I first got the truck, and it was a brand new compressor, I watched them install it and fill the system. Ran it for a few years. Mine also ran off a serpentine belt. Those V-belts tend to vibrate quite a bit i have noticed.

 

[Mastiff]

I don't think there's any DIY way to work on the old style ones, right? Really, I'm lucky that it's working so well anyway. I had it totally discharged for about 10 years in Iowa and the shop I went to here just filled it with refrigerant and it's still working a year later. I thought it would all leak out. I might have lost some since it doesn't seem super cold, but it's still going.