EVACUATING AC SYSTEM

[73StangCoupe]

All, I'm replacing my heater core and I'm to the point of removing the box, so I need to evacuate the AC system.

Has anyone used this from Harbor Freight Tools:

http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html

I've checked with my local advance auto and auto zone and they don't LOAN or SELL anything like this. I saw a youtube video on it, it looks real easy:





If anyone has ANY suggestions on how to do this... let me know! Looking for help!

 

[mustang7173]

Yo 73Stangcoupe,

Dude! Nice! I am rebuilding my heater/AC box since I have my dash assembly out. I was wondering how to check the A/C evaporator while I had it out. This might be a solution to my question.

mustang7173

 

[73StangCoupe]

Yo 73Stangcoupe,

Dude! Nice! I am rebuilding my heater/AC box since I have my dash assembly out. I was wondering how to check the A/C evaporator while I had it out. This might be a solution to my question.

mustang7173

Yes, according to the videos I've seen and everything I have read, you can also check your system for leaks while evacuating it. I have the 73 Car Shop Manual, Vol 3, Electrical, it goes over the entire system with some pretty good diagrams and pictures starting on page 36-42-01. If you don't have the shop manual, I can probably upload the section, it's only 12 pages. Just let me know. I'm going to wait to order this until I get some responses from someone that has used this thing... hopefully!

 

[mustang7173]

73StangCoupe,

Thank You very much for the offer. I do have set since I bought my 1973 Coupe. I currently have the dash out, plus installing new floor pans. Thank You for your research into this device.

mustang7173

 

[73StangCoupe]

73StangCoupe,

Thank You very much for the offer. I do have set since I bought my 1973 Coupe. I currently have the dash out, plus installing new floor pans. Thank You for your research into this device.

mustang7173

No problem. I also have a 73 T5 Coupe and have my entire interior and dash ripped out. Thank God I don't need new floor pans, I'm no welder...

I'm surprised no one else has chimed in yet.

 

[gpierce]

Not sure how that's supposed to check for leaks exactly other than to put a valve inline to turn the valve off (is that a check valve on this one) and see if vacuum is maintained.

 

[caspianwendell]

Always use a manifold set. you could run the pump through it and be a lot more accurate.

 

[73StangCoupe]

Gpierce, the guy in the video said if the pressure on the gauge holds between 25 to 30 then you don't have a leak in your system, if it drops to zero you have a big leak. Is he full of it??


Caspian, something like this?

http://www.harborfreight.com/a-c-manifold-gauge-set-92649.html

I guess I'm just trying to do this on the cheap... Thanks!

 

[mustang7173]

The purpose of the evacuation process is to draw a vacuum on the system to remove moisture and other contaminants. The other purpose would be to test your system to see if It had any leaks. If the vacuum does not hold, then, yes, you have a leak. No need to waste the oil and the refrigerant until this is fixed. The other Harbor Freight device will work nicely too.

Thank You 73StangCoupe

mustang7173

 

[will e]

I used one of those for my Jeep AC. (1982 jeep, r12) You want to borrow a manifold/guage set from Autozone, apply the vacuum, close the manifold valve and see if it maintains vacuum for several hours. If it did you are probably leak free.

But to really evacuate moisture from the system you need to run a vaccum against the system for several hours as well. I am not sure how much of a vacuum that type can create. My AC friend said not enough. What you are trying to do is get the vacuum to a low enough level that water vaporizes and is removed from the system. Any water in an r12 system will combine with the freon and become corrosive.

 

[73StangCoupe]

Thanks for all the responses, the help is much appreciated.

 

[gpierce]

Right, that's what I was saying. You need a valve inline and close it off after applying vacuum to check for a leak.

I have an older version of that and I can get down to about 27" with it. That's close to enough, but I think you're supposed to go down to 30. Also with mine you need a BIG compressor to keep air flowing through the thing for the 30 minutes you need to boil off the moisture. Of course I never really thought of putting a valve in and just run it down then close off Not sure if that one is better or not, but my compressor is 60 gallon/14CFM and it can just barely keep up with it.

 

[73StangCoupe]

Right, that's what I was saying. You need a valve inline and close it off after applying vacuum to check for a leak.

I have an older version of that and I can get down to about 27" with it. That's close to enough, but I think you're supposed to go down to 30. Also with mine you need a BIG compressor to keep air flowing through the thing for the 30 minutes you need to boil off the moisture. Of course I never really thought of putting a valve in and just run it down then close off Not sure if that one is better or not, but my compressor is 60 gallon/14CFM and it can just barely keep up with it.

Based on what you're saying, I could be in trouble. I have a 6 gallon, 100 PSI compressor. It works for filling tires and balls but that's about it. Well, anyway I ordered the Air Vacuum Pump and it should be here next week. I'll let you know how it goes. Thanks...

 

[caspianwendell]

Gpierce, the guy in the video said if the pressure on the gauge holds between 25 to 30 then you don't have a leak in your system, if it drops to zero you have a big leak. Is he full of it??


Caspian, something like this?

http://www.harborfreight.com/a-c-manifold-gauge-set-92649.html

I guess I'm just trying to do this on the cheap... Thanks!

That will work

Right, that's what I was saying. You need a valve inline and close it off after applying vacuum to check for a leak.

I have an older version of that and I can get down to about 27" with it. That's close to enough, but I think you're supposed to go down to 30. Also with mine you need a BIG compressor to keep air flowing through the thing for the 30 minutes you need to boil off the moisture. Of course I never really thought of putting a valve in and just run it down then close off Not sure if that one is better or not, but my compressor is 60 gallon/14CFM and it can just barely keep up with it.

Based on what you're saying, I could be in trouble. I have a 6 gallon, 100 PSI compressor. It works for filling tires and balls but that's about it. Well, anyway I ordered the Air Vacuum Pump and it should be here next week. I'll let you know how it goes. Thanks...

Run it until compressor is low, close the low side manifold, and unplug the hose until air catches up, repeat until you have the lowest vacuum possible and post your results

 

[VegasFastback]

I have a universal certification in refrigeration and you're taking a chance buy not pressure checking the system. There is a chance that the vacuum will pull together pieces if they're broken right while pressure applied to the same break will push them apart. Its not hard to put some pressurized nitrogen to it and be absolutely sure the system is sealed.

 

[gpierce]

Can you use Co2, or do you need to use Nitrogen?

 

[73StangCoupe]

Thanks Vegas... I have never done any work on an ac system. For now all I need to do is properly unhook the system without screwing anything up. Once I get the new heater core put in and get everything back together I'll take it to a shop to get the ac recharged properly.

 

[VegasFastback]

You might be able to get away with using CO2 but its is common practice to use nitrogen because it doesn't react to anything. Also Ii forgot to mention. Be careful when you evacuate the system, there is a $10,000 for releasing the refrigerant into the atmosphere.

 

[73StangCoupe]

Thanks Vegas, I read that some where. I'm trying to avoid that happening. I want to do this correctly and get the rest of the job going. I should have the stuff from harbor freight tools this coming week.