If the oil charge is a couple of ounces too much, would this cause all these A/C problems we are having? And if the dealer does some work to the A/C system and the tech adds more oil "to be on the safe side", could this cause more problems than it fixes?

 

hmmm guess not

 

Yes, too much oil can cause a decrease in A/C performance.


MikeyB

 

But since the increased amount of oil decreases the contact area between the refrigerant and the evaporator core it would effect the A/C performance on both sides of the cab. The usual symtom of too much oil is decent performance while everything is fairly cool then decreasing performance as the vehicle runs and the temp goes up.

 

Similar poor performance will be had with too much air in the system. This is one very common item overlooked by a lot of techs / shops in our area. If a tech does not have his/her lines purged of air it will be injected into your system. or if their machine has too much air it will do the same.

 

I am an HVAC tech not an MVAC tech, but the principles are the same. A refrigerant system is engineered to cool with a specific refrigerant charge. You cannot add to it, nor take away from it for good measure and expect it to work correctly. Too much oil often will collect in the expansion device at the evaporator coil causing poor performance. It can also form a liquid slug and damage your compressor. I would suggest you have the complete charge recovered, the system evacuated deeply and new refrigerant weighed in to exact factory specs.