1. When to use the AIR CON TOP UP system

When automotive air conditioning systems are low on gas the air they blow out will not be as cold as when the system is fully charged. If the system is totally out of gas it will cease to blow out any cold air at all. Using AIR CON TOP UP you can top up your own system and have freezing cold air again. There is also a sealer which can seal small holes in plastic and rubber ‘O’ rings for when the system has leaked out all of its’ gas.

2. How to tell if the compressor is running.

It is very important to be able to tell if the compressor is working. The reading obtained from the gauge will not be reliable if it is not known whether or not the compressor is running. There are three ways to check if it is running or not.

Firstly when you switch the air conditioning on you should hear a small click and the engine should increase its’ rev speed. This click is the compressor coming on. If you hear this then it is working fine.

Secondly if you are able to identify the compressor in the engine compartment then you will see it spinning when the air conditioning is switched on and then stopping when it is turned off.

Thirdly you can use the gauge in the kit. When connected to the low side port of the car the gauge reading should fluctuate when the compressor is running. Usually the reading with the compressor running will be lower then when it is at rest. Therefore if when you turn the air conditioning on and off you get immediate changes in the reading then you can assume that the compressor is working.

3. Obtaining reading on the gauge/hose

Firstly make sure that the tap on the hose is screwed completely down.

You must then connect the gauge to the low pressure charging port of the vehicle. There are 2 ports on a vehicle the high and low, the gauge will only connect onto the low port so no mistake can be made.

Hold back the plastic ring, push the connector on to the port and release the ring, you should here a click as the connection is made.

Ideally the outside temperature should be above 15C/58F, turn the engine on and set the air con in the car to its’ coldest setting and use the recirculation option if applicable and leave all vents open with the fan on full. The reading can then be taken. Refer to flow chart for action to be taken.


With the hose and gauge separated from the car, wind the tap of the hose completely to the up position. Having decided which can to use, screw it carefully onto the tap of the hose making sure it is not cross threaded. Screw it on tightly and then back half a turn.

Connect up the hose to the low side port connecter of the car as above.

Once connected to the car with the can attached to the hose turn the tap into the fully down position, this will both pierce the can and close the valve stopping any leakage.

Invert the can then unscrew the tap slowly to empty the contents of the can into the A/C system.

Once the contents of the can are empty screw the tap back down to close off the can.
Disconnect the hose from the vehicle and then unscrew the can very slowly from the hose pointing it away from you as the last of the gas may still have to escape.