This 2000 Nissan Xterra came in with the complaint that the a/c works good sometimes but it may not work at all at other times. The easiest place to test is at the thermistor lead connector (white) at the bottom left of the glove box.
It can be done without removing the glove box but it is easier with the glove box assembly out of the way. There are two screws located in the lower corners. Two screws located in the upper corners and two screws located in the upper center at the latch bracket.
The testing is as follows. Key on and engine running with the a/c turned on: Green/orange wire will have battery voltage from fuse #29 in the underhood fuse box, the Blue wire will have battery ground from the a/c control assembly and the Blue/black wire will have a nominal 4-5 volts with the thermistor off (temperature below 40 degrees F) and less than .5 volts with the thermistor on (temperature above 45 degrees F). The thermistor assembly applies a ground to the circuit which is sent through the dual pressure switch and then on to the engine control computer. This one failed the test and needed to be replaced. The proper way is to remove the refrigerant and then the evaporator case but I prefer a simpler way. It can be a little painful but it only takes about ten minutes from this point to change it. There are three phillips headed screws that have to be removed along with three 10 mm headed screws as shown in the following pictures.
Once the screws are removed, the two halves of the evaporator case can be separated enough to look in, see the thermistor, carefully and a little painfully insert your hand into the box and removed the sensor. Slide the new one in, in the reverse order and install the previously removed screws. The long tab pointing down slides into the evaporator fins and tab pointing to the right is the actual thermistor bulb.
I have heard that they switched to a two wire sensor around 2003 as well but have not worked on one myself.
Also check the in-cabin microfilter. If badly clogged, the A/C system could come on normally; but because the thermistor air flow is blocked by the dirty cabin air filters, it will turn the compressor off for a long time and the cooling process will stop.
I noticed some diff based on engine, year (and even early or late production for ’03 4-cyl); such as dual pres. sw vs. triple pres. sw. and anti-seize sw. Is the 3-wire part (TCA) used vs. the 2 wire part (intake sensor) in some cases? The ECM cuts control to A/C for various reasons: cranking eng, acc pedal floored, coolant too hot, eng. speed too low, & even operating P.S. with fully released acc. pedal. Itr uses inputs from throttle posn sensor, P.S. oil pres. sw, etc.
Since your is a 2003 and only has two wires, I would suspect that your truck uses a different part number and design. I only gave the information for the 2000 Xterra, that I was working on. You will need to contact your local dealership and have them look the part up by your application.
Sparky, I have a 2003 xterra and am experiencing the same symptoms. However my thermister / tca is a two wire prong on one end with a metal probe on the other. I have purchased the part # mentioned here 27675-9Z000 which is the one you have pictured. What I don’t understand is how you managed to connect what you have pictured on that 2000 xterra? As mentioned mine is a 2003 but since the new tca is 3 wire it doesnt connect in my factory 2 wire prong/connector. Please help!