heater question.

[BLK95TA]

so for the last few years my heater hasn't worked very well. it would let out lukewarm air unless the air temp outside was like 65 or higher in which case i wouldn't be using the heater anyway..it would sometimes blow warm air but only for like 10 secs or so then you could turn it off and turn it back on and it would do the same.

it was actually kind of cool today (43) and when i took the car for a spin around the block (in a tshirt and shorts, lol) i decided to try the heater and to my amazement its blowing hot air now all the time.

could i have had a clogged cooling system or something causing this? i had the heater core checked once last fall and they said it was fine and the car was stored all winter and then in the spring i had to have the radiator replaced due to a pinhole leak. could the radiator have been clogged or something to where it wasn't allowing the heater to work and now that the radiator is brand new, it works fine?

just curious as to what would have caused the heater to not work but now blow warm air like its supposed to when i never had the heater serviced.