Hi all,
Last year, my wife's A/C stopped working on her 2006 Saab 9-5 SportCombi, and upon closer inspection, the 3 rivets that hold the A/C clutch plate to the shaft adapter had sheared. I found a replacement assembly online and installed it and it was fine. The summer progressed, and the efficacy of the A/C decreased steadily.
This spring/summer the car wasn't driven much due to quarantining, but I decided to check the A/C pressures. With the A/C on and ambient temps around 70 degrees, the low side was 35 psi and the high was between 110-130psi.
I added freon (only freon, no oil/dye) but I've forgotten my ending values. A/C worked better, and maybe as well as it should (i rarely driver her car so I don't know what normal feels like).
Simultaneously, I replaced the power steering pump with a reman from ACDelco from what I thought was a whining original PS pump. The reman sounds the same, so perhaps the sound I hear is normal, or from some other accessory.
I drove the car a bit and all seemed fine, THEN I load the wife and kids into the car for a day at the lake. Car is running and A/C pumping, everything and everyone is loaded into the car and I watch as she turns the wheels to pull out of her spot, and BANG, broing!
She pulls back in and I look in the engine bay and the Serpentine belt is off. Swap cars and she's off. A couple weeks later, I investigated and the A/C compressor shaft spins fine, all pulleys spin fine, the PS pump and water pump all spin fine. I reinstall the serpentine belt and there are no problems.
I pulled up the Nissen flow chart on pressures and ambient temps and go and see if the Compressor is doing anything odd. The static pressures at 94 degrees ambient were 120 low and high side. A/C on and compressor engaged, it's 35 and 200, but chart says High side should be 250-300ish. I add freon till I get to 35 and 250psi and call it a day.
As I was adding freon, fans were on low speed, but then they suddenly bumped to high speed and remained there for a bit. I stopped adding and they returned to low speed. I added more freon and they came back to high speed and remained there during the entire filling.
I have a number of Qs:
Why would the rivets fail on the compressor clutch plate? I assumed it's a fail-safe so in the event of a seized compressor, the pulley would still spin and the car could still drive.
Why would the serpentine belt derail? I assumed it was a seized pulley, or accessory, and I was really leaning towards the compressor, but they all hand spun without event.
The Low Speed High speed change while filling could be totally coincidental, but does this bit of info change what you're thinking?
Could a compressor intermittently seize? Is this a rare but witnessed event?
Should I just bite the bullet and but a kit off rockauto for $350ish that includes a new compressor, condenser, drier, and expansion valve and gaskets? I presume the recovery of refrigerant would cost around 50 bucks and I can do the install myself. Buying freon would likely add a few more bucks but the kit comes with oil.
I would need to flush the system. I have a air compressor. what else would I need?
Thanks everyone!