A/C vacuum down still?

[chevyrider838]

Hello. I'm replacing my a/c compressor, a/c hoses, accumulator and condenser. Is it still necessary to vacuum down before I recharge after these parts are installed. I was thinking that everything that would have moisture is being replaced right? Or no? Thanks for the help guys!

 

[evilunclegrimace]

Hello. I'm replacing my a/c compressor, a/c hoses, accumulator and condenser. Is it still necessary to vacuum down before I recharge after these parts are installed. I was thinking that everything that would have moisture is being replaced right? Or no? Thanks for the help guys!

You still have to vac the system down to check for any leaks. The air has moisture in it humidity and all that. Water vapor will boil at 28-30 HG of vacuum. that is why it is recomended to 1) vac the system and see if it will hold the vacuum for 45 minutes to an hour and 2) vac the system for an additional 45 minutes to an hour to draw all of the water vapor(moisture) out of the system. Then the vacuum in the system will draw the refridgerant into the system

 

[1998_K1500_Sub]

Yes, as @evilunclegrimace noted.

I’ll add that I like to leave the system sit overnight to see if it will hold vacuum at 30” (or less if you’re above sea level… 24” in Denver for example).

If it doesn’t hold vacuum you need to find out why.

You might benefit by studying a few threads before you continue.

Here is a long thread from earlier in the year; there are a lot of nuggets within regarding many facets of the process (charging with liquid, lubricating O-rings and fittings, evac / vacuum procedures, vacuum pump oil, gauge set "checks" to do prior to evac / charging, replacing the service valves, PAG oil distribution prior to 1st startup, etc.).

1996 C1500 Reg Cab AC not working - what all do I need?

Hi, I have a 1996 C1500 4.3 reg cab 8ft bed and the A/C is not working, just blows ambient air. Is there anything simple I might be able to check to see if the system is salvagable? I was thinking if the system is bad, to maybe buy a kit or the individual parts needed to replace and flush...

www.gmt400.com

 

[L31MaxExpress]

Even if the system is clean and dry, you do not want air in the lines. Always vacuum.

 

[chevyrider838]

Thanks all!