Do I need to?

[dashhho]

The compressor will not turn on in my truck, I'm fairly certain its due to low refrigerant levels (I had charged it maybe 3 years ago when there was similar issue). I plan to tear the vehicle down and remove the engine etc... If the system was leaking and that caused the refigerant levels to be low - will there be any remaining in the system? As in do I need to take it into a shop to pull anything else out or is it likely there is nothing left in the system and I can remove the system and get on with my build.

I will take it to a shop to properly vaccum down the system and get new stuff in the system.

 

[Uncle Gump]

Only way to know for sure is to hook a gauge to it...

 

[Curious Hound]

Sometimes the system will leak down to a lower pressure, then seal and hold that residual. So, as Gump said, only way to know for sure is with gauges or just push one of the schrader valves briefly and listen for the hiss. No hiss, no pressure.

 

[dashhho]

If the low pressure side is empty would the high pressure side still hold some residual?

 

[Curious Hound]

If the low pressure side is empty would the high pressure side still hold some residual?

Only if there are significant blockages in the system. There is a schrader valve on both high side and low side. You can check both.

 

[Dirtman]

Refrigerant recovery systems have become pretty affordable, you can buy a vacuum pump and guages for under $200 which is probably what a shop would charge you to do it anyway...

 

[dashhho]

Thanks guys. The high and low pressure shraders opened with no hiss - sounds like shes empty!

The good - dont have to evacuate right now....
The bad - have to fix the system later....

 

[19Walt93]

Just a suggestion: have it charged and the leak located before you tear it down, they'll have to evacuate it for you but it may save you having to take it apart a second time after reinstalling the engine. If you need an evaporator core or condenser it might be a lot easier to change with the engine out of the way.

 

[Curious Hound]

Just a suggestion: have it charged and the leak located before you tear it down, they'll have to evacuate it for you but it may save you having to take it apart a second time after reinstalling the engine. If you need an evaporator core or condenser it might be a lot easier to change with the engine out of the way.

Great ideas. Some places might charge it with nitrogen for leak testing so there isn't any refrigerant discharge involved.