Simply want to Add Refrigerant to A/C

The simple answer is that yes, you could buy a can of R-134A that doesn't contain compressor oil, and add to the system.

The complex answer is that if you add too much refrigerant, then you will degrade system performance. Hence if you care about that, you will invest in gauges that measure the high and low system pressure and follow the repair manual instructions. Good luck.

 

I suggest that you visit your local discount auto parts store and buy a can of refrigerant that is labeled to show it contains no oil. Also buy the double gauge instrument while there, have the repair manual info available (consult techinfo.toyota.com if needed) and you should be good to go.

 

You don't need to buy the double gauge instrument. Many recharge kits now come with a low side gauge, and the can with the hose is around $20. If you want to invest in the high side gauge, the pressure should be 198 to 228 pSI. The gauge you purchase will show you the safe range for the low pressure side.
Keep the hose only for use on the prius. If you use it on another car, you may then contaminate the prius if you use it on it again in the future.

 

You can also use the old thermometer in the air vent method. When the air coming out is around 50° F then you have enough refrigerant in the system.

 

If anybody else comes across this, hard to beat the site glass method like in the old R-12 days. In fact that's what the repair manual tells you to do. The manifold gauge pressures they give you are almost nonsensical. Simply fill slowly until the bubbles in the sight glass disappear. You'll never get a perfect fill that way, but will NOT overfill it if you stop when the bubbles stop.

The only way to get a perfect fill is to put the exact amount in, and that can only be done with specialized equipment.

 

In a Prius (I know this was true for Gen 1, and I believe it stays true for the later generations), the A/C uses a subcooling condenser, which means the proper charge is not obtained right when the sight glass bubbles stop, but when a certain additional weight of refrigerant (100 grams? check the manual, don't trust my memory) has been added past the point where the bubbles stop. So that presupposes you also have a decent postal scale or something to have your refrigerant can on, so you can tell when the specified additional weight has gone in.

You should also make sure you do this under the exact conditions stated in the manual (surrounding temperature within the given range, doors open, fan speed as stated, etc.) ... conditions that are too different can change when the bubbles disappear, or they might not disappear at all if the weather is too hot, which would lead you to overcharge.

I am not looking in a Gen 2 manual at the moment (I've used up my techinfo days for now), so anybody with the manual handy, please do fill in more details, or correct me if I'm wrong about something ... I'm going by what the procedure was for Gen 1.

-Chap

 

I have a 2005 also and I put in envirosafe refrigerant and there stop leak and it blows 40 out of vent . Www. Es-refrigerant. com