A/C service 2005 Tahoe - Seals are Important

[redhat]

This past February when the 6.0 was swapped in my Tahoe, a new A/C compressor and condenser were put on the truck by a friend. It has been pretty warm lately, so I was itching to get my system charged.

Bought a vacuum pump and gauges and put tried to pull a vacuum on my Tahoe's A/C system. I could not get over 10in of mercury. I could hear air suction from around the compressor suction and return lines.

Ran to the parts store and picked up a factory air seal kit -- figuring maybe a seal was bad. Got home with the seals, pulled a line off and there was NO seals... well that explains it! I just assumed the old seals were put in, but I'd bet they stuck to the old compressor.

Put new seals on lubed with a little PAG oil. Hooked the manifold gauges back up and it quickly pulled a vacuum. Let it sit for about an hour and it held just fine. Pulled a vacuum for another 45 minutes to completely evacuate the system. Added a little over 2 12oz cans (I do have rear HVAC but have the rear A/C lines capped off). I now have about 40 degree F air coming out of my vents.

Happy and pleased. I guess seals are important.

 

[Chris142]

Should have replaced the accumulator and those round metal and rubber seals go on dry.

 

[FZ1]

This past February when the 6.0 was swapped in my Tahoe, a new A/C compressor and condenser were put on the truck by a friend. It has been pretty warm lately, so I was itching to get my system charged.

Bought a vacuum pump and gauges and put tried to pull a vacuum on my Tahoe's A/C system. I could not get over 10in of mercury. I could hear air suction from around the compressor suction and return lines.

Ran to the parts store and picked up a factory air seal kit -- figuring maybe a seal was bad. Got home with the seals, pulled a line off and there was NO seals... well that explains it! I just assumed the old seals were put in, but I'd bet they stuck to the old compressor.

Put new seals on lubed with a little PAG oil. Hooked the manifold gauges back up and it quickly pulled a vacuum. Let it sit for about an hour and it held just fine. Pulled a vacuum for another 45 minutes to completely evacuate the system. Added a little over 2 12oz cans (I do have rear HVAC but have the rear A/C lines capped off). I now have about 40 degree F air coming out of my vents.

Happy and pleased. I guess seals are important.

Good for you, man.

 

[JHZR2]

Should have replaced the accumulator and those round metal and rubber seals go on dry.

I was going to say the same…

 

[redhat]

Should have replaced the accumulator and those round metal and rubber seals go on dry.

Yeah probably should have, it is a couple months old. Oh well.

 

[redhat]

The accumulator has been capped off since the swap so I'm not really that worried about it.

 

[slomo]

Far as O-rings go, yes they need your flavor of refrigerant oil on them prior to installing. Doesn't hurt one thing. Lubes the O-ring and makes it slide on and last longer. Where was the dry O-ring install taught at? Every O-ring be it plumbing or HVAC requires lube for max longevity slash durability.

Far as the accumulator capped off, how is the system working? You need that and the dryer normally found inside. Maybe your vehicle has something else on it??

You always test for leaks under pressure. Like 150 PSI of shop air or nitrogen. Vacuum is not the final leak test.

Glad to hear you have cold air.

 

[brianl703]

Far as O-rings go, yes they need your flavor of refrigerant oil on them prior to installing

I have heard to never use PAG or POE oil on o-rings because those oils attract moisture.

I had heard to use mineral oil.

I use Nylog, or if that isn't available, silicone dielectric grease.

 

[slomo]

I have heard to never use PAG or POE oil on o-rings because those oils attract moisture.

I had heard to use mineral oil.

I use Nylog, or if that isn't available, silicone dielectric grease.

NOTHING wrong with Nylog. I would use that if you have it over and refrigerant oil.

Never use silicone grease on an HVAC system. Stick with the Nylog.

 

[brianl703]

Never use silicone grease on an HVAC system.

Why not?

They seem to think it's OK in the UK:

HC-CARGO

 

[slomo]

Because you don't want anything foreign contaminating the system. Nylog doesn't do that.

I could care less what the UK thinks. Or what any other group says. Do your own research on it.

 

[wtd]

I have heard to never use PAG or POE oil on o-rings because those oils attract moisture.

I had heard to use mineral oil.

I use Nylog, or if that isn't available, silicone dielectric grease.

I use Nylog too. Good stuff.

 

[brianl703]

Do your own research on it.

I did. As a result, I came to the conclusion it's not a problem to use silicone grease on AC o-rings.

 

[redhat]

A/C has been blowing good and cold since I performed this work at the beginning of the month. With the blower on middle setting, the A/C on lowest setting will hit 38-42 on my thermometer. I am pleased.

 

[slomo]

I did. As a result, I came to the conclusion it's not a problem to use silicone grease on AC o-rings.

Did you find it on the internet?

This is the first time I've ever heard about using silicone grease in an automotive AC system. Only thing I've read is you use the same refrigerant oil that the system has OR Nylog. Nothing else to dispute.

Here is an AC forum about this. Check it out.

Which lubricant to use on o-rings in R-134a system - Automotive Air Conditioning Information Forum