Should air conditioning oil be changed?

[noodlerooney]

Wasn't sure where to put this post. Was wondering if the air conditioning oil, mixed in with refrigerant, should be changed and how often. I would assume that since it is an oil, it would break down over time and "sludge" the system. What do you think? It seems like I am ignoring this system.

 

[Kestas]

No... this is one part of a car that shouldn't be touched until it needs repair. Except for cleaning the leaves from the condenser, there's no maintenance (from a practical or anal viewpoint) that you should do that would help maintain the system.

One thing I do recommend is that people protect the condenser form rock damage. Some cars have an 'open grille' design. On these cars you should put 1/4" hardware cloth at least an inch in front of the condenser.

 

[noodlerooney]

I used an aluminum gutter guard to screen my open lower grill, looks good and is functional. The reason I asked about the AC is that most cars need recharging after several years, like mine does now. And according to AC forums, the right way is to evacuate the system while checking for leaks and then recharge with new refridgerant and oil. The recharge in a can that you see at WalMart that is introduced on the low pressure side is not the correct way to do it. They specifically say not to introduce any sealers and to use virgin oil and refridgerant in the amounts specified on the label under the hood. To do it right, I would have to buy a new set of AC tools, how can I resist?

 

[Kestas]

I think there's something lost in the translation.

It's only happenstance that cars need recharging after a few years. Some work a long time before repair. It's usually corrosion that causes leaks. But leaks can happen for many reasons. Sometimes the leakage is normal and it can be topped off. If it leaks out in under a few months then there's a leak that needs to be fixed. All leaks must be found and fixed before further service. It is an art to find them. I can only find them on a system that is under pressure.

Once the leak is found and fixed, then you go through the exercise of flushing the system, vacuum, and recharge. Some oil leaks out with a refrigerant leak. That's why flushing is done to remove the old lubricant (and contaminant debris) and you have a starting point for a proper oil charge.

I agree that no one should use sealers in an a/c system. Once you get a set of manifold gauges and a vacuum pump, you're set to DIY repair of a/c systems.

 

[Ray H]

The oil used with R134a refrigerant is a synthetic PAG (polyalkalene glycol). Very stable stuff as long as it's not exposed to moisture. I wouldn't worry about it "sludging the system".