Anybody here ever had a heater core that wouldn't allow much air through it?

ok, my car doesn't blow all that strong when the blower motor is on high, but it's liveable. I replaced the motor and it helped maybe 10%

the main problem (especially this time of year) is when I have it on VENT and I turn the other slider to HEAT, the air slows down to a trickle. It blows through the vent when it's on COLD, but not HEAT

it's not like it deverts it to the defrost or heating vents, it just goes away

I'm afraid my evaporator may be a little clogged too, which is why the overall ventilation is reduced... but if I'm only getting 50% through the evaporator, i'm only getting 10% through the heater core

Can these be cleaned, or do they have to be replaced?

 

I think when its on "vent" air is diverted to the ducts by your knee.Not the by the ash tray, but behind the radio on th console.At least thats how i recall.

Kinda hard for a heater core to plug up.Being its inside the dash.

 

I would think so too.... but according to this diagram, I can't think of anything else it could be..




as you can see, there's a door that diverts all the air through the heater core when you select the hotter temp. if the heater core fins are clogged, the air wouldn't have anywhere to go

 

even if that is the problem... I have to decide if it's worth fixing... I do live in texas, and the percentage of days that I really need a heater are less than 20%

Imay just wait until it goes out, then I'll have fix it.
but then again, fixing it before it makes a mess all over the carpet might not be a bad either. If it's plugged up, that means it's OLD, and could go out at any time

 

Ttt

any other possibilities of what could be causing this problem?