An apparatus for replacing coolant includes a communication unit, a pressure gauge, a flexible tube, a conical plug, a valve and a vacuum producer. The communication unit includes a first port, a second port and a third port in communication with one another. The pressure gauge is connected to the third port. The flexible tube is connected to the first port. The conical plug includes a liquid channel extending throughout the conical plug. The liquid channel is connected to the flexible tube. The valve includes a switch and a pneumatic quick coupling device. The switch is connected to the second port to selectively allow or stop communication of the pneumatic quick coupling device with the second port. The vacuum producer includes a pump and a hollow insert extending from the pump. The hollow insert is adapted for connection to the pneumatic quick coupling device so that the pump is operable to produce vacuum in the valve.