Spannerhead

1999 2WD 4.6l. Symptoms: Very little heat from vents on full warm. Engine warms up normally, runs perfectly and never overheats. Barely enough heat from vents to start defrosting windshield after 10 minutes or so of driving. Dangerous for a truck parked outside in the winter.

Here's my heater hose situation:



Based on that, I have a clogged heater core, right? No chance it's just the blend door? If it's a clogged heater core, is there any way to "purge" it without ripping apart the whole dash area?

Thanks.

PIMPIN F150

first off is check coolant level and is it full? if full then first before i would replace the heater core i'd try to bleed the cooling system. jack up the front end that way the reservoir is the high point and air is directed to it. if after bleeding it. it still doesnt work try to flush it. with a garden hose shoot water into the outlet as you will do a reverse flush.

Alxe

I'm just throwing this out there but the temp **** could be broken, thats what was wrong with mine when i bought it

Spannerhead

Checked out the temp ****; it wasn't broken but the potentiometer shaft was partially stripped. Replaced the pot with one from the dealership ($29 wholesale w/tax).

Backflushed the heater core with a garden hose until the water coming out the inlet ran clear. Hooked everything back up, filled and bled the system with the truck's nose up high and took it for a test drive.

Not scorching hot heat, but definitely a HUGE improvement. More than enough to heat the cab and defrost the windshield now for sure.

It's freezing out there so it was kind of a quick procedure; when it's a bit warmer I'll flush the heater core out even more thoroughly.

Thanks for the input, guys.