63 Riviera A/C Help

[tkeiser1]

After a summer of international travel, and a couple "trips-from-hell," I finally got a chance to get back to work on my AC. I have successfully gotten the original R12 system operating, and all components apparently functioning properly. When charging the system, I discovered and fixed a significant leak. I am a DIY guy, not an expert on anything, so I don't know how to think about the following situation.

 

When I draw a vacuum, the guage reads about 60 Hg. Over a short period it drops significantly to the 40 range. However, it has now held steady for a month at about 35.  I'm wondering if the initial drop indicates a minor leak?  Any thoughts?

 

Tom

Edited August 13, 2022 by tkeiser1 (see edit history)

[Jim Cannon]

3 hours ago, tkeiser1 said:

After a summer of international travel, and a couple "trips-from-hell," I finally got a chance to get back to work on my AC. I have successfully gotten the original R12 system operating, and all components apparently functioning properly. When charging the system, I discovered and fixed a significant leak. I am a DIY guy, not an expert on anything, so I don't know how to think about the following situation.

 

When I draw a vacuum, the guage reads about 60 Hg. Over a short period it drops significantly to the 40 range. However, it has now held steady for a month at about 35.  I'm wondering if the initial drop indicates a minor leak?  Any thoughts?

 

Tom

Tom-

The drop to 60 to 40 to 35 is your vacuum pump pulling the water vapor out of your system. It's normal.

 

When you say it stays at 35 for a month, is that with the vacuum pump not running?  If so, that's good.

 

It never hurts to run the vacuum pump down as low as you can go and let it sit to see where it goes.

 

You can break the vacuum with R-12 and then pump that down again to dilute any residual air and moisture down before charging with R-12. Most people overcharge. Go easy, keep track of how much you are putting in. It is easy to add a touch more when needed.  Too low of a charge will freeze up the evaporator. Most people think it's the other way around.

 

Turbinator has seen it all.

 

 

[tkeiser1]

Jim,

 

Yes, that with the vacuum pump off. 

 

Question . . . what do you mean about "break the vacuum wiht R-12"?

[Jim Cannon]

Introduce pure R-12 into the system slowly to get rid of the vacuum in the system (pump off), bring it back to zero psi or a little above zero psi gauge, then use the vacuum pump to pull it down again. This will get more of the air, nitrogen, water vapor out of the system before the final R-12 charge.

 

If you have already charged the system with R-12 and are using it, then forget it. Too late.