Go5.3tt06

iTrader: (1)

Quick question- I have girlfriend son 17, bought him a truck 2001 gmc sierra 4.8 RCSB the heater seem not blow hot just warm. I replaced the therostat, seem same. I looked at engine temp operation at 185-195 at most. Winter getting cold here, he need good heat for truck. Do you think it could be heater core? I pulled door blend actuator use my hand twist the flap cold good, but hot nothing only feel warm little. I wanted to make sure before pull dash out to replace the heater core. I not looking forward for that lol.

shakenfake

Tell him to wear a jacket

Go5.3tt06

iTrader: (1)

hes 17, im all ask to see if anyone who have experince with similar issues the heater.

arthursc2

iTrader: (5)

Check the core for obstructions, do a reverse flush on it

make sure the cabin air filters are clean and make sure the dash vents are clear

Jeff71

I second the core flush.

RedXray

EDIT: re-read you've done the stat

Go5.3tt06

iTrader: (1)

theres no cabin filter. I strongly think its heater core, but I want to make sure. How hard replace heater core?

arthursc2

iTrader: (5)

01 should have cabin filters, fyi

RedXray

My 00 has them

MikeGyver

iTrader: (5)

My 2000 didn't come with a cabin filter. Watch videos on replacing the heater core. It's pretty tough. Definitely try flushing the core first.

I had help. After I blew the A/C charge, he worked under the hood while I worked inside.