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I did check the voltage and ground. Both were OK.
The compressor did come prefilled with oil, but I don't remember the exact amount. Bad memory says 4 or 6
Clever idea to run torque check. It takes about 8 ft.lb to start rotation
I did not rotate the compressor before installation like you suggest.
Sounds like its new compressor time.
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
8 lb ft is a bit much to spin the A6 compressor,
try spinning it a few revolutions and see if it loosens up if not there may be an issue with the compressor
really need to know the high side pressure, can you add something like this
R12 #6 Inline Charge Fitting with #6 Male & Female O-Ring, would need to validate the line size.
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
To be clear the compressor should be mounted in its brackets and then spun 8 to 10 revolutions by hand to clear the cylinders of oil and allow the oil to settle in the sump.
Did you flush the system before you installed the new compressor ?
If your belt is tight and it's squealing , and you can't turn it by hand after a new install ....
I thought a video might help explain my problems. I can't even leave the compressor engaged long enough to get a low side reading. I wouldn't play this loud.
Sorry about the poor quality I had trouble doing this. It also looks like I didn't have the low side shrader valve open for this one.
I thought a video might help explain my problems. I can't even leave the compressor engaged long enough to get a low side reading. I wouldn't play this loud.
Sorry about the poor quality I had trouble doing this. It also looks like I didn't have the low side shrader valve open for this one.
That appears to be an Apple only file type.
Think you really have to pursue a high side port.
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
It looks to me that the compressor is going to need replacing,
Like I commented prior I've seen these compressors run at 500 psi and not slip the clutch with the correct voltage supplied. You've validated the voltage and air gap, both within spec and if high head pressure was the issue the compressor would have to run for a few minutes to create the head pressure, from the video it starts slipping as soon as the clutch is engaged. The only issues that would cause this is either liquid in the compressor or a bad compressor.
Do you know what refrigerant was in the system prior to the work you performed, I ask because the A6 compressor should have 525 viscosity mineral oil or equivalent in it. If someone did prior work to the AC system and replaced the oil with a different oil this may cause issues for the compressor.
The A6 should turn by hand without much force,
If you do pull the compressor I would look into adding a high side service port, looking over diagrams of the 73 vette AC system there should be 2 service ports at the compressor on the hose manifold, it looks like someone may have installed the wrong hose set.
I was able to watch and listen to the vid. Every time he engages the ac clutch it clamps down properly, but cannot turn the compressor so the clutch face squeals like a banshee.
My thoughts are return the compressor (if possible). If not, take the compressor apart to determine why it's locked.
I wish it was the belt, but it's the clutch slipping. The belt is really tight. That was the first thing I checked and tightened.
I had problems trying to do a video I could upload. In this particular video I didn't have the **** on the connector screwed in. The low side does drop quickly when the compressor is turning.
The system seemed fine when I was filling it, and I was driving around with the thermometer in the duct checking, but this problem quickly developed. It's useless now.
I'm sure. I used a die hook to swing the compressor out and tension the belt when this first started. No real way to tension more.
I do have a location where I can add a high pressure fitting like Neal recommended These are the connections to the condenser, in and out are different sizes, and I will try to locate an adapter to match the in line. Larger one on top of picture.
First off your is slipping and I stand by that. Like I said earlier I can see the pulley almost comes to a stop. It's not the wagon wheel affect. How do I know, because the belt portion between the compressor and crankshaft pulley is flopping around like a fish out of water. Also I know what a belt sound when it's slipping. Just because you're at the end of adjustment doesn't mean it's tight. It means you got too long of a belt. You need a belt about 2" shorter. But hold on, check your compressor mounting. Something looks loose.
Last edited by Fly skids up!; Jun 25, 2025 at 04:18 PM.
I wish you were here Fly so we could look at it together.
For openers I did put on a belt that was 1 inch longer to fit this pulley, must be a little bigger.
I am not out of adjustment, picture enclosed
I also have a video for you trying to show the belt tension. Not the best way but you get the idea. It's tight.
All bolts are tight on the compressor mount.
MacTrader
Before discarding the slipping-belt theory I would try spraying the belt surface with some belt dressing (cheap at your local store)...... HOPEFULLY it could just be a cheap belt this would let you know that..... I had belts that would screech no matter how much I snugged until a guy at NAPA told me to buy a brand name belt.... I really did not believe him, but HOLY COW..... no more screeching and not tightened to all get-out.
Methinks it would be well worth the belt-dressing experiment at this point.
Originally Posted by Fly skids up!
Sure about that? It sure looks like the pulley almost comes to a complete stop in that video.
I sprayed the belt with belt dressing. ( Sticky gooey stuff ). The belt must have been slipping because now it just stalls the engine from a 1000 rpm fast idle. Just too much drag from the compressor.
Seems pretty clear now what I have to do to fix this.
