I have a 300D >The temperature reads 100c after its running in the summer heat.I checked to see if the plastic fan is working and it does not seem to be working.I found what looks like a temperture sender by the top hose (it has one wire ) is that the senser for the fan?Next to that is what looks like a sender with two vacume ports on it,One of the ports is plugged up. What is that for? Any info would help.