Intermittently working Air Conditioning of Jeep Grand Cherokee 2001
When it works, everything is fine. Otherwise, the LED of the A/C switch does not light up and there is no cold air either. Sometimes tuning the ventilation knob could let the A/C work but cannot cure the problem.
I googled a lot but didn't find any write-ups on Jeep WJ with these symptoms. Many Jeep owners had faulty blower motor/blower motor resistor/blend door actuator. My reasoning on my faulty A/C is very simple: Now that it could work intermittently, the major components such as compressor/condenser/ accumulator and blower motor have very low possibility of malfunction. It might be some bad switches, connectors or other electrical components.
a: Gently pry each of the four corners of the center lower/upper bezel away from the instrument panel. A used dinner knife would serve this purpose well.
d. To confirm that the vacuum switch is faulty, we start the engine and push connector to see if the A/C or electrical fan is working. Anyways, if any difference of the symptom happens when we let the connector move without taking it apart. Then we are sure that the connector need service. In my case the connector was somewhat loose, and the A/C began to work when I firmly pushed the vacuum harness toward the panel. This indicates that the vent vacuum switch is the least culprit of the problem.
e. To service the connector, I have some lessons: First, we should be careful that there are three springs inside the connector and they would bounce away to nowhere if we pry off the three clips carelessly. So let the vacuum harness lift SLOWLY off the metal axle in the knob. (If one did miss some springs, the spring in some click ball-point pen is a good alternative.) Second, mark the relative location of the metal axle in the knob (the intersection of the axle is a half circle) and the vacuum harness.
f. Use some cleaner (I use WD-40) to clean the inside of the connector which is a printed circuit. Note there is a plastic round seat for the three springs with a metal cover at half way of the metal axle in the turning knob. Normally, it is impossible to restore the relative position of the springs and their cover because they are not held together by anything, unless the first two owners serviced it and missed something.
I employed my 50 lbs fishing line to hold the springs to their plastic seat with the metal cover. The hard fishing line is the best material that I can imagine and can do this job. (Sorry, forgot to take pictures. It looks quite funny.)
g. I think, if i am not naive, that the connector of the vacuum harness might need some sort of sealing. So I dripped some ATF on the connector. (The fifth picture shows the oily connector).
h. Hook the connector with the metal axle in the turning knob. Note there is a metal bead on top of the plastic seat of the springs. Since the connector is loose. I used fishing lines again to hold the connector firmly.
I. Reverse the steps that we took down the upper/lower bezels and restore the panel.
J. Test. It works like a charm for me. Thanks for reading. ;-)