Thread: Overheat and blowing cold air

Here's the background. 2001 GP 3.1 L Temp goes up to approx. 230 degrees with no heat. Temp drops down to 170 still no heat. Bounces back and forth between 170 and 220 or so. After driving for 10 miles, heats a little. So I changed the radiator cap, no luck. Changed thermostat, no luck. Let idle in garage, wait for thermostat to open and air bleed valve removed. Once thermostat opened, then I poured more antifreeze in. Put air bleed valve and cap on. Took for a 10 mile ride - heated great. Today, car had no heat again. I noticed hole in hose that connects radiator to overfill resovoir so I replaced. Purged air again and now heats great. I think I'm getting air into the system but don't know how. I'm assuming radiator, water pump and heater core are all good if I can get good heat after purging the air out. Other than that, I'm out of ideas. Any suggestions?

Update - car's heat is still working today. After posting, I did a better job of searching this site and it sure seems like many people are getting air trapped in their system. The purge done properly is important.
Oil looks good so I don't think it's a headgasket. Which elbows? Could this cause the coolant to sometimes get to the heater core and sometimes not? Because after I purged the air, then the car heated awesome. I'll keep everyone updated.

Update - Day 2. Heat is still working. Keeping my fingers crossed that it was an air pocket.