Recharging the Air Conditioning

Recharging the Air Conditioning

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Keeping a full charge helps keep you cool in the summer and keeps the A/C system working without problems. Over time (2-4 years) the refrigerant has a tendency to escape past seals and o-rings lowering the efficiency of the air conditioner. And since the refrigerant also acts as lubricant for the A/C compressor a total loss of R-134a may cause the compressor to seize. Luckily checking the A/C pressure is cheap and easy. However if your A/C goes from full one month to empty the next month you probably have a leak somewhere that needs fixing before the system can be charged.

The Xterra A/C Port

Tools needed:

R-134a refrigerant hose with gauge.

1 Can of R-134a refrigerant.
(Both can be found for under $20 at most automotive parts stores.)

Find the A/C check port.

The A/C check port is located between the compressor and the evaporator (in the passenger cabin), on the Xterra it is on the driver side of the firewall covered with a blue cap.

Attach filler hose/gauge, and measure pressure.

The connector is a quick disconnect fitting similar to what is used for air tools. Just slide the sleeve back and press onto the A/C port. Be quick or some oil will spray out onto the firewall.
The pressure should be checked with the engine running and the A/C on. To make sure the A/C compressor stays on turn the blower motor setting to Hi and temperature setting to cold, the compressor clutch should engage and start turning.
Read the instructions with the pressure gauge to check for the right pressure; most gauges will be color coded to tell you if the pressure is too low, too high, or just right.

Checking the A/C pressure (blue is the "safe" zone)

Add refrigerant if the pressure is too low.

Read the instructions with your filler hose to be sure; most use a needle and valve to pierce a sealed can with the R-134a in it.
First back off the valve all the way so the needle is up where it won't accidentally pierce the can.
Screw on the can of R-134a.
With the A/C Running turn the valve till the needle pierces the can and the refrigerant is sucked into the system.
When the pressure reaches the right pressure on the gauge, close the valve and remove the filler hose from the A/C port. If there is still refrigerant in the can don't unscrew the can from the hose, save it for later.
Clean up any mess and throw away the empty R-134a can. The hose can be kept for later fillings and pressure checks.

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