misc hvac question

May 06, 2013, 02:06:23 AM

once upon a time my hvac fitting was leaking around the needle valve so i had to keep the platic cap on real tight. id have to add some charge to it once in a while.

well the day came where i was adding and the needle valve competely failed and i lost all my charge.

i purchased new fittings and went home, took off the old one (low side i think (blue), and added a new fitting.

i had two cans of charge and knew i had to take it somewhere to get properly charged but....... curiosity got to me so i started the car and turned on the AC, added charge and it took!.

what did this happen? there was no vacuum on the system, how did it charge up.
thats been likeover a year or more ago and its still going strong but i dont understand how it was even possible.

thoughts?

misc hvac question

Reply #1 – May 06, 2013, 07:11:39 AM

When you charge as a gas (can upright) to the low pressure side, the pressure differential from the can to the dead system causes enough charge to transfer that the cycling switch can close and engage the compressor. From that point the compressor will draw in from the can. The low pressure side is the inlet, or also known as the suction side, that alone pretty much explains it. However, since your system wasn't vacuumed down first, you will have air in the system along with refrigerant. This is not ideal.