Overfilled refrigerant on Tahoe?

I recently added some R134 to my 1998 Chevy Tahoe. The commercial filler gauge was at the low end of the acceptable pressure level. I added one small can of refrigerant which put the gauge at the top end of the same region (but not in the overfill region). Since then, when I turn on the AC I get a loud “rubbing” or “grinding” sound for a few seconds, which goes away. I speculate it might be the belt sllipping from too much back pressure on the compressor–but what do I know? Opinions, and is this likely to damage something?

When servicing A/C always use high and low pressure gauges, no other right way.

It could be an overworked compressor causing the belt to slip. The obvious thing to do is check the belt and tensioner.

It’s always risky to rely on a single gauge attached to the low pressure service port. You also need to know what’s going on on the high pressure side. A full set of gauges can be purchased for around $50. A ggood investment if you’re going to do your own a/c recharging.

The problem did not occur until after I added the refrigerant. I am inclined to let a little out and see if I can get it to stop.

I suppose someone should mention that venting refrigerant into the atmosphere is a violation of federal law, and has some pretty hefty fines attached to it. Do so at your own risk.

The right way would be to discharge any excess into an EPA-approved storage cylinder.

There is only one correct way to charge a modern cars air conditioner, and that is to recover the refrigerant out, and weigh the refrigerant charge back in to the factory specified amount. Unfortunately this takes specialized equipment requiring it to be taken to A/C shop.

I thought R134 was developed in order to prevent the kind of atmospheric damage the older stuff caused.

R134 may be ozone friendly, but unfortunately it has global warming potential, and therefore still needs to be recovered.