Automotive Air Conditioning Information Forum

Here's the story, I need some suggestions. I've just revived the A/C on my 1964 Ramber Classic stationwagon. It's pretty much a clean install with new condenser, dryer, expansion valve and new Sanden 508 compressor. I used the original evaporator but flushed it well to remove any old oil and trash. I pulled vacuum for about 6 hours then charged the system with three cans of R134a. It's cooling great. Outside temp is 90 degrees and I'm getting 45 out of the center vent, sometimes going down to 39. Low side pressure is running 15-20, high side 250 at 1500 or so rpm. I can drive it around and it works fine, but I've noticed when going over 3000 rpm the compressor really squalls. Sounds like a dry bearing vibrating in something. I've checked to make sure it's not the belt slipping or the clutch. The sound is definitely coming from the compressor. I can feel the vibration on the suction hose.

The compressor itself was full of oil from the factory. I have added about 3 oz of oil to the system. The compressor has a little smaller pulley than the engine pulley so I'm sure it's being overdriven slightly. It's rated to 6000 rpm and I'm sure It's no where close to that.

Is it possible I just need to add more oil? I know putting too much oil is a problem. Any suggestions would be appreciated. Thanks

Belt issue

Bad compressor

What are the pressure readings?

Low side pressure is running 15-20, high side 250 at 1500 or so rpm.

All/100% of SD508s are noisy at 2800 compressor rpm. Comp itself is ok.
The addition of a aftermarket suction muffler reduces noise 20% and a discharge muffler reduces NVH another 15%.
Oil quantity is ZERO influence.
Get use to it or swap for a SD7H15 or a swashplate drop in or a SD708 (bracket mods req'd)
hotrodac
"How to Air Condition Your Hot Rod"

ice-n-tropics wrote:All/100% of SD508s are noisy at 2800 compressor rpm. Comp itself is ok.
The addition of a aftermarket suction muffler reduces noise 20% and a discharge muffler reduces NVH another 15%.
Oil quantity is ZERO influence.
Get use to it or swap for a SD7H15 or a swashplate drop in or a SD708 (bracket mods req'd)
hotrodac
"How to Air Condition Your Hot Rod"

Been so long, I forgot about the Sanden rumble.

ice-n-tropics wrote:All/100% of SD508s are noisy at 2800 compressor rpm. Comp itself is ok.
The addition of a aftermarket suction muffler reduces noise 20% and a discharge muffler reduces NVH another 15%.
Oil quantity is ZERO influence.
Get use to it or swap for a SD7H15 or a swashplate drop in or a SD708 (bracket mods req'd)
hotrodac
"How to Air Condition Your Hot Rod"

Well, that sucks. I ran it a little yesterday just to make sure I had my facts straight. I can feel the "sound" in both hoses at lower rpms, but when it gets up to around 3000, a little before, it's like someone has flipped a switch and it's screaming. Sounds like it should start smoking at any second! This old car seldom hits higher rpms other than just before a shift. Although I had considered swapping out the rear end which would make it more likely. Wish I had known about this prior I would have used the SD7H15.

Smitties and underhood/firewall insulation might keep the rumble masked
hotrodac

Should not be screaming. Sanden's do have a rumble as mentioned. But again it's not a screaming sound by any means.

Hi Mr. dogbone,
Since the A/C is unacceptable, I'll take it off your hands.
Mother Hubbard's hotrodac

I've been busy, but now had some time to get back on this.

I've gone through and checked my pressures again and decided it was a bit over charged. I've removed some of the refrigerant and now have pressure readings of 7 on the low side, 165 on the high side at 1500 rpm and about 85 degrees ambient temp. I getting about 46 degree air out of the blower. Was getting 39 degree air prior to lowering the pressures. Still getting the loud racket when it goes to 2800 rpm, and once the racket starts it keeps it up until the rpm drops to below 2600 or so.

I have always thought the low side was too low, while the high side is about normal. When I idle down the low side runs up to 10-15 range. I always thought the low side should be in the 18-20 range? Is it possible that the expansion valve is not releasing enough refrigerant and there's nothing there for the compressor to suck in so it sort of runs dry?

Here's a short video of it running, it's not hard to hear the noise.
https://www.amazon.com/photos/share/jeD ... 3ovKkznsjx