2000 Pontiac Montana low coolant lite - no heat

One of two things could be going on. First check your coolant sensor, this could be faulty. Next check your thermostat,it could be beginning to stick.

Your in for a long haul this problem is all over the internet. I have the same vehicle and here is your symptoms:
1. Low Coolant Light Comes On
2. Temp indicator goes up and down
3. Temp indicator sometimes goes all the way to 210
4. Heater doesn't work or only works when your on the highway at high RPMs.
5. It will hold 15 pounds of pressure for 24 hrs so it's not a leak.
6. You have changed the themostat, radiator cap, had the system flushe and still the same problem.
7. I have had a head gasket and an intake gasket replaced in the last year.

Nothing seems to solve the problem.
The only solution I found not to let the van warm up more than 1 minute before I drive it. If I do that the problem rarely occure. I have asked the dealership and they tell me I need a headgasket even though my van passed the sniff test. (tail pipe sniffer looking for coolant). I'm just gonna drive it till the whells fall off. Good luck