Ford F150 heater problem

[FastGame]

1998 F150 heater stopped working. The temp dial does nothing, one heater hose is hot the other is cold, all fuses are good. Is there something that controls the coolant flow through the core ? bad relay ? clogged heater core ?

Any ideas welcome

 

[javacontour]

Probably a clogged heater core. Not on an F150, but on other cars, I've been able to flush them out with a garden hose attached.

Certainly worth a try before you swap it.

Not to mention you can see if it's really clogged or not. If it won't pass water from the garden hose, it won't pass what your water pump is producing.

If it does, the problem is likely related to the blend door, etc.

But the hoses with differing temps lead me to believe it's a clogged heater core.

I'd start there.

For one take on this from ChrisFix and his Ford Ranger

 

[nwjones18]

Probably a clogged heater core. Not on an F150, but on other cars, I've been able to flush them out with a garden hose attached.

Certainly worth a try before you swap it.

Not to mention you can see if it's really clogged or not. If it won't pass water from the garden hose, it won't pass what your water pump is producing.

If it does, the problem is likely related to the blend door, etc.

But the hoses with differing temps lead me to believe it's a clogged heater core.

I'd start there.

For one take on this from ChrisFix and his Ford Ranger

+1 I've had good luck backflushing them with a garden hose. hook the hose up to the normal exit side (cold hose) and unhook the other one and run it into a jug. You'll be amazed the junk that comes out.

 

[The_Eric]

Heater control valve? Make sure the little Grey hose is still on and that it has vacuum to it.

 

[joegreen]

Does your blower motor work? Can you hear the blend door move when you turn the temperature dial from hot to cold?

 

[WobblyElvis]

One heater hose hot, the other cold indicates there is some [little] flow through the heater core. Either partially plugged or the heater control valve is only passing a small amount of fluid. I would first suspect the valve.

 

[MNgopher]

As I recall that vintage of F150 did not have a heater control valve - they sent flow to the heater core all the time...

Based on the description, it does sound like a clogged heater core.

 

[FastGame]

Thanks to all who replied, it was clogged heater core.