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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: DTrain on September 01, 2014, 12:22:19 pm

Title: I'm an idiot, AC help
Post by: DTrain on September 01, 2014, 12:22:19 pm: So, I've an '84 Silverado that I just put an A6 AC system on. I put the whole thing together and took it to the shop, they pulled vacuum on the system and charged it up for me. A couple days later I noticed a little noise at the compressor and narrowed it down to where the lines come in the back. I felt around back there and noticed a tiny bit of system oil. So, I went to tighten it and got about an 1/8 of a turn when the bolt spun and there went all of my charge. So, my question is now that my system is "drained", is it truly empty? Am I at ground zero in regards to oil too? Does it need to be flushed before I fill it? I guess I'm just curious as to what step I need to take from this point.
Title: Re: I'm an idiot, AC help
Post by: bd on September 01, 2014, 01:28:13 pm: The bigger question is, "Why did the bolt 'spin?'" Is the bolt stripped - are the threads in the compressor damaged? Was the wrong bolt size used - incorrect diameter, pitch or length? Was it just overtightened? You need to figure out what went wrong.

A closely related question is, "Why was it leaking refrigerant in the first place?" Were the wrong o-rings used? Were the o-rings installed dry? Was the manifold bolt cross-threaded and the o-rings not properly clamped?

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When you lost the refrigerant charge, guesstimate how much oil you lost by the amount of oil coating the area surrounding the blowout.

Until you get it repaired, cap the lines and compressor ports to prevent entry of dirt and moisture. Chances are good that you will not need to reflush the system or replace the accumulator again if you cap the system off. In any case, the system will need to be evacuated again and recharged. Any repair of the compressor head (if needed) will have to be addressed by someone knowledgeable, who can evaluate the situation first hand.
Title: Re: I'm an idiot, AC help
Post by: DTrain on September 01, 2014, 05:21:40 pm: It has new orings, looks like the threads were compromised somehow, it almost seems to me that I maybe put in to short of a bolt, but I'm not sure why that would mess up the thread. But reguardless, the bolt failed which caused the initial leak. When I tried to tighten the bolt it broke loose. I guess I need to try a longer bolt and see if it threads?

So, I can't seem to see much oil back there, just a little of what to me I would describe as over spray. But in any case, it sounds like I'm gonna have to take it back in? No way of a home remedy in this case?
Title: Re: I'm an idiot, AC help
Post by: 78BIG-TEN on September 01, 2014, 07:24:14 pm: easy way on A-6.Make compressor level,loosen screw on the side close to the bottom,(7\16 wrench I think) a few turns and see if oil drains out .got oil its probably ok.Rule of thumb an abrupt leak add 3 ounces.longer bolt tighten ,evacuate and charge.If compressor rattles shoot a couple more ounzes of oil.I think bolt should be 3\8 fine and screw into compressor a minimum of 1\2 inch.good luck
Title: Re: I'm an idiot, AC help
Post by: DTrain on September 01, 2014, 09:12:59 pm: I like the way that sounds. If I can do it myself by all means and if I end up spending much more money on this truck then I have been in the last couple of weeks, my wife is gonna freak out. Anybody have any huge disagreements with that? Sounds like a good easy thing to me.
Title: Re: I'm an idiot, AC help
Post by: DTrain on September 01, 2014, 09:23:32 pm: Also, is it truly critical to pull vacuum on it again? Is it a sin to just do a backyard charge?
Title: Re: I'm an idiot, AC help
Post by: bd on September 02, 2014, 01:23:11 am: Quote from: DTrain on September 01, 2014, 09:23:32 pm
Also, is it truly critical to pull vacuum on it again? Is it a sin to just do a backyard charge?

That depends on whether you want optimally cold air to blow out of the dash vents in hot weather.

Proper evacuation removes unwanted air and moisture. Air and moisture are counterproductive to A/C function. The system will not adequately cool w/o suitable evacuation using an A/C vacuum pump - preferably connected through a gauge manifold followed by proper charging.

IMO, if there is no obvious visual evidence of gross oil loss and the proper amount of oil was added originally (10-12 oz, including the oil in the compressor), don't add extra oil "just because."

A6 compressors will build as much as 450-500 PSI head pressure under the right circumstances. Just make sure that the hose manifold is properly attached to the back of the compressor. Choose a Grade 8 bolt with the maximum penetration the compressor will accept w/o the bolt bottoming in the hole.

You should be able to do most of the work at home as long as the compressor threads are intact. Otherwise, it may be prudent to seek another opinion from someone local, who is experienced and who you feel is trustworthy.

If you elect to proceed with evacuating and charging the system yourself (you may be able to rent a vacuum pump), BE SURE TO WEAR SUITABLE EYE PROTECTION during the process! Liquid refrigerant can cause instant frostbite and freeze your eyes! Charge the system through the low side service port with the vehicle outdoors. Be aware that refrigerant drawn into a running engine through the carburetor will produce highly toxic phosgene gas blowing out the exhaust. The respiratory effects of phosgene are not to be taken lightly! Be very careful.
Title: Re: I'm an idiot, AC help
Post by: DTrain on September 02, 2014, 05:51:30 pm: Well, I got home from work today and put in a new longer grade 8 bolt with some lockite on it, I was able to get it in there good and snug. I called my local mechanic and he said he'd get right in as soon as it showed up, so I guess I'll take it in and wait to see what pulling some vacuum does. Hopefully in a day or two I'll be back to cruising in style. I'll let you know what the outcome is.
Title: Re: I'm an idiot, AC help
Post by: DTrain on September 03, 2014, 05:05:32 pm: My truck went to the shop today, held vacuum and is blowing freezing ass cold yet once again. Thanks for the replies everyone.
Title: Re: I'm an idiot, AC help
Post by: bd on September 03, 2014, 06:16:09 pm: You're most welcome! Now, put on a sweater and enjoy some of that FREEZING COLD AIR!!!