A/C system torque specs?

greenoliver1 · September 30, 2021

Hey guys! I’m replacing the compressor in my 2015 Silverado LT with the 5.3. After replacing both my condenser and upgrading to the steel discharge line, as well as adding the bracket, my compressor started leaking from the back a few days ago.

So I got the replacement GM genuine compressor, expansion valve, and a desiccant bag. I’m wondering what the torque specs are for the nut that holds the suction and discharges lines to the compressor, as well for the nut that holds the lines to the condenser and expansion valve. I’m assuming since they all have the same stud, they should all be the same torque spec. Also, while I’m here, can the desiccant bag be replaced with the condenser still in, or do I need to remove the condenser to replace the bag? Thanks all!

tbarn · October 1, 2021

16 lb ft. Per GM, the condenser will have to come out.

greenoliver1 · October 1, 2021

Thanks for the info! I just ordered some Nylog, should I use the Nylog on the sealing washers, or just on any O-rings?

greenoliver1 · October 1, 2021

14 hours ago, tbarn said:

16 lb ft. Per GM, the condenser will have to come out.

should I use Nylog Blue on the sealing washers or just on the standard green O-rings?

CrawlSlow · October 1, 2021

You shouldn't have to use any additional sealing liquid. If it's leaking, the leaks would need to be repaired.

Two reasons I can think off that would cause freon to leak from compressor; 1, Bad compressor. 2, you have a blockage in your system causing very high pressure.

greenoliver1 · October 2, 2021

4 hours ago, CrawlSlow said:

You shouldn't have to use any additional sealing liquid. If it's leaking, the leaks would need to be repaired.

Two reasons I can think off that would cause freon to leak from compressor; 1, Bad compressor. 2, you have a blockage in your system causing very high pressure.

hey there. I was told the sealant isn’t needed but helps, so I’ll probably add it. Dealership said that the pressure reading of output on compressor was alright but it’s leaking from the back. They said everything else was fine. So I’ll be replacing compressor, expansion valve, all seals, and removing condenser to replace the desiccant bag

tbarn · October 2, 2021

I have never used sealer. That is what the seal is for.

greenoliver1 · October 2, 2021

1 hour ago, tbarn said:

I have never used sealer. That is what the seal is for.

I’ve been told the nylog just helps the protect sealing washer and o-rings from heat and the elements, and it can go on flared fittings to help seal, seen lots of good reviews on it

tbarn · October 2, 2021

Use it if it makes you feel more comfortable. Belt and suspenders approach I guess.

CrawlSlow · October 2, 2021

Since your are replacing all those parts, make sure to use the correct oil. The oil that comes inside the compressor may not be the correct type. Always double check.

greenoliver1 · October 3, 2021

On 10/2/2021 at 1:28 AM, tbarn said:

Use it if it makes you feel more comfortable. Belt and suspenders approach I guess.

Yeah, I figure if it can help, why not. I really don’t want to do anymore AC work on this truck, so I’m hoping this should help. I’ve been reading lots of good things about the blue nylog so I’m more confident in it

greenoliver1 · October 3, 2021

On 10/2/2021 at 2:10 AM, CrawlSlow said:

Since your are replacing all those parts, make sure to use the correct oil. The oil that comes inside the compressor may not be the correct type. Always double check.

I’m not going to be doing any oiling, I’m just going to install the parts, then take it to the dealer for the vac and recharge. I’ll explain my situation to them and they can handle the rest hopefully

Snowcamo · October 3, 2021

I'm an HVAC tech by trade. Though the fittings are different I use a sealer on any joint that does not require torches. Nothing like added security. I started with nylog then moved on to Liqivac. With nylog you want to make the surfaces/ oring clean with alcohol or acetone to aid in adhesion. Put it on lite so it does not squish into.

I do agree a fitting shouldn't need a sealer, but with the quality of things it can't hurt.

Edited October 3, 2021 by Snowcamo

CrawlSlow · October 4, 2021

30 minutes ago, greenoliver1 said:

I’m not going to be doing any oiling, I’m just going to install the parts, then take it to the dealer for the vac and recharge. I’ll explain my situation to them and they can handle the rest hopefully

I get what you are trying to do. Please note, all new compressor comes with oil to keep it lube. Some comes with the correct oil type while others do not. It's important that you check as you don't want to mix the two oil together in your system. You probably will end up paying more than the money you're trying to save.

Why not just take the parts to the dealer and pay for installation labor, atleast it will be done right. I don't know how much the dealer will charge for a complete system flush but I can only imagine $$$$$$$$

greenoliver1 · October 4, 2021

15 hours ago, Snowcamo said:

I'm an HVAC tech by trade. Though the fittings are different I use a sealer on any joint that does not require torches. Nothing like added security. I started with nylog then moved on to Liqivac. With nylog you want to make the surfaces/ oring clean with alcohol or acetone to aid in adhesion. Put it on lite so it does not squish into.

I do agree a fitting shouldn't need a sealer, but with the quality of things it can't hurt.

i wasn’t aware I needed to clean the sealing washers with acetone, good thing I have some here! I seen online everyone said the nylog was like nickel anti-seize, a little bit goes a long ways! Thanks for the info!