Chrysler Repair: 1991 Caravan temp guage sticking, coolant temp, mileage vehicle

Question
The temp guarge needle seems to be sticking.  I can tap on the dash and it will take will read normally.  How does one remove the instrument cluster, and can this individual guage be serviced/replaced?  I replaced the temp sensor a few years ago.  Are there resistance readings that can be taken as the engine warms up?

I am trying to ascertain whether I have a heat problem, as I saw bubbling in the resevoir for the first time.  (HOT day, city driving, air conditioner on)  Didn't notice any trouble as the guage was stuck within the normal range.  

I drained and flushed the cooling system and filled with new antifreeze mixed 50/50.  All seems to be well, but the guage is the first line of defense against a problem.

This a low mileage vehicle for it's age.  80k and I am the original owner.

Thanks for your input!  ~ Loren

Answer
Hi Loren,
Thanks for the generous feedback. I have the envelope addressed and stamped, so I'll copy the pages tomorrow and it will be on its way to you.
Roland




Hi Loren,
On the gauge question, I need to say that I don't have a '91 shop manual which is the point in time where the electronics of the body were integrated with the digital data bus. The '93 manual I have shows the temp gauge to be part of the digital data bus and speaks of replacing the temp gauge unit rather simply. I can send you the page that show how that is done. In terms of checking what the gauge is 'seeing' on the data bus, that requires a readout box. But I believe you can check the coolant temp sensor to be sure that it is generating the proper signal. It should read 7,000 to 14,000 ohms at 70F and 700 to 1,000 ohms at 200F. If that were inaccurate you would probably also notice a degradation of the engine performance because that output not only is used to run the gauge but also to control the mixture (if indeed your gauge is run via the data bus, as opposed to a separate temp sensor for the gauge only which was the approach of the '80's). So aside from that I will be pleased to send you the info on removing the gauge if the dash is indeed the same as a '93.
Roland