AC Compressor Noise after re-seal
 

I have just completed a Griffiths AC upgrade with new evaporator and extra condensers but kept the original compressor. Griff provided an amazing amount of information/help all along the way. I tore down the compressor and used new seals and Ester oil. Put compressor back in car while trying to find a local shop to recharge the system.

I have driven the car with everything in and under a vacuum several times, not using the AC, with no issues. On about 1 1/2 hour drive over the weekend, I started to hear a loud droning noise from the right rear in the last half hour of driving. It was the AC compressor. Questions: Should the compressor make noise with no refrigerant in the system? Did I, more than likely, not put it back together correctly and the compressor bearing or something else has now failed?

Any ideas on why it would make a lot of noise is greatly appreciated,
John

Before you do anything else, I'd recommend removing the compressor and inspecting it closely. Look for any signs of wear, damage, or debris. Check the bearings for play and ensure everything moves smoothly

Simple test one, remove the belt and be 110% sure it is the compressor making the noise. If it is not connected and you hear a noise, it wasn’t the compressor making the noise.

The pressure switch should prevent the clutch from engaging so the compressor should not be turning, just the clutch pulley.

If the compressor is indeed making a noise when it is only the pulley turning, you have a problem.

From what I have read, rebuilding a compressor is very difficult to get right at home. Even difficult when companies do it. Best bet, get a new one.

Yep, removed belt and noise is gone. Compressor was working "fine" before AC system upgrade but decided to re-seal it to be on the safe side. Searching for a new one now.

It could be just the clutch. Its best practice not to leave the system under vacuum with potential to run the compressor as its cooled and lubricated via oil in the refrigerant. Are you sure compressor was not operated? Now that you have the belt off, can you turn compressor over by hand? Disconnect lines, pull compressor and let it drain oil onto clear glass dish, look for metal particulate or waxy oil. Use a Kim wipe to swab inlet & discharge ports for debris. Turning over by hand with fingers over ports, you should feel suction on low side port and pressure on discharge port. Plug line fittings with a rubber stoppers when disconnecting suction and discharge hoses to minimize moisture and junk into system. Griffiths systems work great, mine was installed by PO in 2002 and the best is Griff's support with knowledge.

I agree with Spetrow's advice. I am guessing the AC was never switched on during your drive. Therefore the compressor clutch was not engaged (hopefully) so it shouldn't be a problem with the compressor. If it were engaged, no lubrication in the (absent) circulating refrigerant means the compressor will likely be damaged.

AC wasn't turned on. I have ordered a new compressor to be on the safe side and to finish this upgrade. Even though it is starting to cool off I don't like leaving this unfinished.

Thanks for the questions, comments, and advice.

Remember A/C is the best defroster. It pull moisture out of the car. Modern cars run A/C and heat that teh same time to defrost the windows. So just because it's getting cooler doesn't mean you may not want it working. :)

And our beloved 911s are likely the only cars ever that have a totally separate heater, air conditioning, and fresh air system. I have many times had the ac on for me, and my wife has the heater running on her side.