NRF is proud to offer a new tool to the AC market for 2021 

16 Feb 2021

The new sight glass can save you time and money when investigating air conditioning faults. It also enables a visual inspection of the condition and flow of the refrigerant and can also give an excellent indication of any problems. With this sight glass you can easily discover impurities, such as humidity, presence of leak stop, gas(?) and dirty lubricant.


The sight glass is easy to use >

> Create a vacuum in the sight glass and hoses Start the engine and switch on the AC

> Connect HP (High Pressure) hose to the HP valve of the AC system (red), keeping the sight glass in an upright position

> Slowly open the HP port and fill the sight glass to 3/4 of the volume

> Close the HP port and wait a couple of minutes for the gas and oil to settle


Once it’s settled – this is what you should be getting >

> The refrigerant and oil are in good condition.

> The correct type and amount of UV tracer is used.

> Mixture is clear and transparent.

> No further action required.


Too much UV dye >

Mixture is green/yellow and not transparent

Possible problems >

Compressor seizure due to change of viscosity and lubricating properties




Wrong type of oil and/or not recommended oils (e.g. PAO) >

Two separate liquid layers, not mixing refrigerant and oil, transparent.

Possible problems >

Compressor seizure due to lack of lubrication performance




The system is saturated with water >

Mixture is not transparent and has a Light grey/white colour.

Possible problems >

Compressor seizure, cooling performance loss with high concentration is possible.




Mixture of PAG oil and PAO oil >

Two separate liquid layers, not mixing refrigerant and oil, milky white, not transparent.

Possible problems >

Compressor seizure, clogging of compressor control valve


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