my 91 jeep cherokee is heating up at a normal rate but then goes past half way and borderlines on the red and goes down and up alittle as i drive. i tried turning the heat on to open the vents, but it just blows ice cold air i am at a loss and could use some help as this is my dd and need to keep it going. thanks in advance

 

Sounds like your thermostat is stuck shut. It's fairly easy to replace and they are about 15 bucks max with the gasket.

Lemme know if you need to know how to do it

 

Are you losing any anti-freeze?

 

X2 would check coolant levels

 

flush the heater core, replace thermostat, do a compression test cause i bet you warpped your head with that much heat

 

Start with a fresh 195 degree thermostat. I buy mine directly from Jeep or the Stant SuperStat is good. Stay away from el-cheapo stats; they are worthless.

Fresh 50-50 coolant and see where you are at.

What is the history of routine cooling system maintenance on this engine?

You may have more than one thing going on. If the temp of the gauge was that hot, you should have heat in the cab. The heater control valve near the firewall is ALWAYS suspect here first.