just replacing thermal expansion valve in AC, do I add PAG oil when recharging?

I had Toyota dealer do a evac and recharge on my 4runner to address a cold/warm AC during driving and coasting and when they did it they said they couldnt get all the refrigerant in indicating the TXV thermal expansion valve has failed shut. They said I had no leaks but after 286,000 miles it was low on AC refrigerant.

So i refused the repair as it was a just too expensive ($1,189.95) so i bought the Denso TXV and a vaccum kit with R134a (24oz) for my 2003 4runner. I want to evac the gas myself, replace the part behind glove compartment, then pull a vacuum and recharge.

DO YOU ADD PAG 46 OIL? Many say you dont. some say you do. There is no agreement on this and official answers even conflict. Most say you do not add oil unless you replace a major part which Im not. Some say add about 1oz for maintenance when recharging.

What do I do?

 

The surest way to settle this question, would be to pull the compressor, take the plug out of the compressor body and see how much is inside. As far as determining how much oil it should have, you should measure it - and I believe it would be in ounces, or a fraction thereof. The compressor manufacturer (likely Sanden, but could be something else) would be the authority on how much oil should be inside.

However, if Toyota did not record how much refrigerant was removed (by weight) then there is no way to know how much was in the system. There might be a placard somewhere under the hood that lists the total amount of refrigerant by weight that a properly serviced system should contain. Google might be your friend if your vehicle doesn't have the placard.

You could add the ounce of oil just in case, but you probably don't need it. Just remember that the oil as a liquid is not compressible and might cause a problem if you have too much.

 

One more thing: a vehicle of this age, you should look into replacing the receiver dryer. This unit removes water that gets into your system. Your existing receiver dryer has likely absorbed all that it possibly can by now.