Not sure what the problem is, but the heater isn't heating as hot as it used to all of a sudden. It does still work though - all the fan positions (1-4) work and the temperature **** does make it progressively hotter as you turn it clockwise.
I'm wondering if there's a blockage or air pocket in the heater core. With the engine up to temperature, one of the hose carrying coolant to the heater core (on the engine side) near the firewall gets piping hot, but the other one returning from the heater core is quite a bit cooler (still warm though). Does this signal a problem or is it normal for one hose to be much hotter than the other?
Thanks!

 

It's quite normal for the outlet hose to be cooler - the blower is removing the heat from the coolant and blowing it into the cab.

 

Have you checked to make sure you're not low on coolant? This is a fairly common cause of poor heater performance.

 

Yes, filled it up just over the MAX fill line so that's not it. Wondering if there's a blockage or air pocket in the heater core.

 

the vacumme actuated doors in the air plenum may not be opening/closing all the way. If this happens you will not get proper air flow and heat/cooling.