04 Sierra Heating Problem

[56chevy1300]

I have a 2004 GMC Sierra 4.8L 2wd ext cab pickup with 50k miles.

Recently, it has been taking longer and longer to heat up the interior. By the guage, the engine seems to be reaching full operating temp soon that it should be and yet I cannot get any heat out of the vents.

Any thoughts? Could it be the thermostat? Anything electronic? Guage? Filter?

Thanks in advance.

[slug]

i would swap out the thermostat, its only a few dollers.

[89 crew]

If the engine is coming up to temp it won't be a thermostat. It would have to be in the selector between the hot and cold. a heater core plugging up, Or air locked.

[56chevy1300]

If the heater core is plugged / not circulating coolant, would this reduce/stop coolant from circulating through the engine as well?

That would explain the engine temp rising fast and no heat in the cab.

[89 crew]

It wouldn't have much effect on the engine. All it could do is leave the heat in the cooling system/ engine instead of heating the air in the cab. Basically it would be like driving with the heater off to the engine.

[Chris27]

Does the fan blow ok? Might be dirty cabin filters.

[retodd7711]

are you getting air out of the vents. If not it's the filter.