My heater doesn't seem to put out much heat any more?

Hello,

There are a few reasons why the heat might not be working.
First of all, check the coolant level make sure it is correct. As low coolant can lead to no heat due to little to no circulation of coolant through the heater core.
This can also be due to a stuck open thermostat. Which will not allow the engine to warm up to the proper temperature level.
Another possibility is a faulty blend door actuator. The blend door actuator controls the hot and cold air mix. Faulty actuator can fail on the hot or the cold side, leading to no heat or no A/C.

Here is a helpful guide that goes over the typical issues:

https://www.2carpros.com/articles/car-heater-not-working

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.