My girlfriend's 1999 Volkswagen Jetta 2.0L water temp gauge on the dash is not working, needle never rises and radiator fans don't kick on from what I can hear. However, it never shows any signs of overheating. Could this possibly be a thermostat problem? Another issue that's possibly related to this is there is the heater does not work. Blend door sounds like it opens fine when turning the knob and blower motor works fine, just no heat. I thought maybe that could be a plugged heater core, but most of the time doesn't that cause coolant to leak inside the cab on the floor board? I work at a Kwik Kar, so I may try to rule out the obvious first, check radiator and heater core hose temps, coolant temp sensor, then try a coolant flush. After that, if the problems still persist I'll probably just replace the timing belt (if this engine has a timing belt driven water pump??), water pump and thermostat. It has over 300k miles on it, so it's probably long past due for all of this anyways (among other small issues, but for her comfort in the 27F degree weather hear, these are my main priority issues to fix.) I typically avoid working on Volkswagens, so my knowledge on them is very limited. Any help/advice/tips would be greatly appreciated as I haven't worked on too many Volkswagens. Thanks in advance!
Oh also, not sure what the trim model is, but I think it's the AEG engine code. 2.0L non-turbo