There are 6 DTC (service codes) that deal with the engine coolant system
(four related to the coolant temp and one for each fan relay). When you're
moving down the road, the air flows through the radiator and the temp gauge
will stay constant, equal to the thermostats opening temperature (the gauge
will go higher initially, until the thermostat opens). When the vehicle is
setting still, the gauge will climb until the PCM decides to turn the fans
on. This can sometimes be 3/4 or more up the gauge. If you are experiencing
large temp movements up and down as you accelerate and stop, you are
probably low on fluid or have air trapped.
The A/C system must have a Freon leak. The most common place in vans
like yours is the condenser. It breaks at the upper passenger side, where it
mounts to the front of the radiator. Look for oil and dirt in that area. The
service bulletin fix, is to replace the condenser and leave that bolt out.
Three mount bolts are enough.