Manifold Gauge Set Q & A

What is an A/C manifold gauge set?

An A/C manifold gauge set is a service tool which enables techs to keep a close eye on the pressure in an air conditioning system and regulate the refrigerant pressure flow. It is used to diagnose and correct an air conditioning unit that is not cooling properly. The red side of the gauge set is the high-pressure chamber, the blue side is the low pressure chamber and the middle is the utility chamber.

Are brass manifold gauge sets better than aluminum?

The material from which the set is made has no effect the quality of the set. In many cases it is simply a matter of personal preference. In general, the quality of a gauge set should be evaluated by how well it endures high pressure and corrosion from the refrigerant. Another quality indicator is the precision with which the parts were manufactured as this determines the likelihood of leakage.  Check out some brass sets here and some aluminum sets here.

How can you determine the quality of the hoses?

A/C hoses psi ratings specify the amount of pressurize the gases that can go through them can have. There are also ratings which specify the operating temperatures the hose can withstand in Fahrenheit and Celsius. Finally, hoses should meet SAE requirements J2196.

What should I look for in the gauge themselves?

FJC gauges come in 2.5” and 80mm (3.14”) sizes, which are excellent for reading. A good gauge will have a shock-proof design to resist damage after a fall. Without shock-proofing, the mechanism could be damaged not allowing it to be recalibrated.

How do you recalibrate the A/C gauges?

It is necessary to calibrate the two gauges before they are put into use. To do this, open the low valve and the high valve of the manifold after the hoses have been removed. Next, remove the covers to gain access to the calibration screws. Tap the sides of the gauge to reposition the needle so it rests on zero.

I broke my gauge set and need replacement parts

FJC carries replacement handle and stems, gauges, lenses, hoses and hose seal repair kits. You can purchase most of the repair items you would need from your distributors.

LMK 2019

Manifold Gauge Set Q & A
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