2008 Pontiac Grand Prix with no heat

[jamccor]

I recently bought a 2008 pontiac grand prix that has over 140,000 miles on it. It runs great, knock on wood, but the only issue it is having and living in NJ, this is a big one. It has no heat! Temperature never goes past the halfway point and has never overheated either. What are some things I can look at? If there are other posts already out there that discuss that, can someone point me there? If not, I appreciate any troubleshooting tips you guys and ladies may have. Also, I have looked for leaks and found none.
Thanks
John

[Scottydoggs]

car up to operating temps, touch both heater hoses, if they are both cold, or one is hot, one cold the heater core is air bound, it needs to be flushed.

take both hoses off the alt bracket, then a garden hose to one hose till clear water comes out, then flush via the other hose, re install the hoses to the alt bracket with water filled hoses.

[rottonj]

Temp gauge at half is normal, I would look into the blend doors not operating correctly if the hoses don't pass the test.

[rickisrad]

If the above checks out ok then it is the heater core.

[rynoman03]

I had half of my car blowing cold and half blowing hot once. Of course the drivers side was cold. It was the blend door underneath the drivers side dash. I got a blend door actuator from MoradPartsCompany for like 14 bux.