98 S10 heater problems

I have a 98 s10 I am having problems with the heater which just started. the temp gauge goes up to about 210 then back down to 100 and of course it never stays at the normal temp. It does not matter if I have the heater on or off, every now and then when it gets up to 210 I have really good heat for a few minutes then the temp goes back down to 100. replace the theromstat and that did not help at all.

I hope someone knows the fix. Any help would be great

make sure your coolant is full. check your water pump flow. your water pump might be taking a dump.

I have check both and they are good. It seems to heat up for a while at high RPM but I have also noticed that thier is air comming out on the drivers floor vent when heat and ac are off.

sounds like a symptom of air in the system. did you fully bleed the coolant system?

no I have what is the best way to get the air out of the system

I just had the same problem on my '96 grab your fan and spin it if it keeps spinning the fan cluch is bad costs about 50 dollars and takes about 1/2 hour to do

had the same problem was my water pump going out. replaced it and now heater works great good luck

busa_4 was right I had air in the system after I got the air out it works great again. Thanks BUSA_4

Make sure you swap on the new rad cap.

That is how air gets into the system. And don't get the faulty AC Delco, get one from Autozone.