I have a 1994 F 350 that the A/C isn't cooling as well as it should. I know this is r134. I have a manifold set for the A/C that I have used before on other vehicles, so I know how to add the refrigerant. I need to know if I need oil for it before I hook up the gauges to add refrigerant. I saw a TSB about insufficient oil in these systems. That is why I am asking about this.

 

Any leak in the AC system can take compressor oil with it, so it's always a good idea to replenish the compressor oil if you're charging it.

 

Any idea how much I should add? I have seen where these can take 9 oz if they are empty, but not sure what to add at this point.

 

Unfortunately I have no idea how much you should add, and it can he hard to judge depending on the type of leak.

 

You should be ok adding one of the pressurized cans available at the auto shops. It only holds 2 oz of oil. Make sure to add the correct type of oil. PAG used in almost all of the r-134a systems is very finicky about mixing with other types( POE maybe, but definitely not mineral). PAG comes in different viscosities. PAG100 and PAG46 are two that are avaialable. Check your owners manual for correct identification. Use proper care and precaution when adding the oil so as to not add any trapped air in the hoses.

 

1994 calls for 7oz of PAG 46 oil.

 

Thanks for the info guys. Ill get some PAG 46 for it and add a little when I put in the refrigerant.

 

POE oil is fully compatible with all other types of oil in R134a systems, and it's much, MUCH cheaper.