Heater will get warm sometimes but then blows very cold air sometimes. Air conditioner does the same thing in summer. Sometimes there is a puddle under the car so it is leaking something but coolant level is fine. Also sometimes the cooling fans stay on even after the car is turned off.

Steve Allison

• 5569 Answers
• Posted on Feb 28, 2009

SOURCE: heater core blowing cold and leaking coolant

Locating the connections from the engine compartment to the heater core shouldn't require a diagram.
Check the hoses and their paths and you will find two that go through the firewall via a fixed connector; these are the in- and outlet for hot water circulation. Since the hoses have had a dozen years to weld themselves to the fitting, they probably won't be easy to remove; it may be necessary to **** them with a razor blade and pry the hose from the fitting.
If you have a little junk pipe pieces at home, either 1/2 or 3/4 should be a fit to couple these two ends together after they are removed from the connectors that you'll find at the firewall. 

SOURCE: heater fan blowing intermittently or not at all

Most likely it does, if you can hit the motor and it will run. I can't say for sure but you might want to chk. to see if you got a heater blower motor resister. There located (if its got one) around the heater motor and it controls blower speeds, might be worth checking out.

Harvey N Tawatao

• 3854 Answers
• Posted on Aug 22, 2009

SOURCE: 2000 pontiac montana air conditioner driver side

That is correct, the air blend door actuator. "flapper valve" may need to be replaced or cleaned and free from binding up. Good luck and hope this helps. If there is an Auto Zone in your area, they can order the part you need and give you the step by step instructions to removing the old actuator and replacing it if it's damaged. Good luck and keep me posted, be glad to help. 

SOURCE: fan is okay on heater but no warm air coming out.

Could be the valve that controls hot water to the heater core or the heater core its self try flushing the cooling system 1st if that doesn't
help the control wire to the valve may have come loose at the valve or the back of the heat control
hope this helps

SOURCE: my 99 pontiac montana has

I would change the Thermostat. if that doesn't fix it? I would buy a Radiator flush and follow the directions exactly you will be surprised how much junk comes out. That should fix all your heat problems.