Low Temp gauge reading

Noticed some strange things going on in the little red truck this morning!:shakehead
1999 S10, ZR2, Vortec 4.3 automatic 4x4

Had no blower speeds other than high...and noticed the temp gauge running abnormally low. Replaced the cluster fuse and that restored the blower speeds, but the temp gauge is still reading low.

We thought at first it might be due to the unusual cold temps we had this morning and the engine couldn't gain heat out on the highway, but we parked the truck and left it idling while doing chores. Temp gauge never moved up.

Usually it was right up around 195 deg., but now hovers at a couple marks above the 100 deg. mark.
Engine doesn't smell hot...no coolant odor...coolant tank is at proper level.
Heater seems to be working fine and there are no other warning lights lit. All other gauges appear to be normal.

Thanks AF members in advance for your time and any suggestions!

I would watch it for a few days and see what happens. If the heat in your truck seems normal it is most likely the sending unit. This should be a much eazier fix than switching the thermostst.

It could be the thermostat, or the ECT sensor. More than likely a thermostat though. Are you getting good heat in the cab? If not, I'd be very surprised if it wasn't a thermostat.

As for your blower motor only working on high, you probably have to replace your blower motor resistor. It's a series of resistors, one for each speed. Each one has a different resistance, therefore limiting the amount of voltage to your motor. Giving you the multiple fan speeds. Usually when you only have high, this means that your resistor needs to be replaced because the voltage is not going through the resistors. All you have is direct power to the fan, causing it to only operate on high.

Hope this helps.

Thanks for the suggestions: the heater appears to be functioning just fine, altho I think it doesnt seem quite as hot as it used to be (could be my worrying imagination), but I might chalk that up to the fact that the cooling fan seems to be running right from ignition and the engine can't build enough heat to make it up.

Solved the blower speed issue with the replacement of the cluster fuse...fuse looked good, but when we replaced it, the blower worked fine on all speeds.

The place where I work detailing cars recently got a diagnostic computer, so we'll see about plugging it in and getting an error code.

Thanks again AF members for taking the time to read and reply: this forum is the best around and the support is great to have for mechanically challenged folks like me~gives us a place to start looking!:grinyes:

03cm, i dont think he has a resister pack does he? should be a 'modual' (fancy way of saying expencive as shit computer chip) if the fuses keep blowing ide say the modual has high draw (it works like an on off switch, turning the fan on and off realy fast, this is what controlls fan speed, the frepuency at which the fan moves) but those hardly go bad (resistor packs go bad, not the new and improved ones) ide make sure there isnt a dead short if the fues blows again

Thanks, DM...so far so good and no more fuses blown yet :rofl:
Haven't had a chance to get to the diagnostic computer, but the little red truck seems to be functioning fine otherwise.

We'll be sure to check the fuses too, to make sure there aren't any other weak or blown ones.

Thanks again for the thoughts...!