Heater core?

[rwljpl]

the heat in my 85 k10 is not working. The a/c does work. The coolant system seems totally fine. There are no leaks coming from the heater core. How should I trouble shoot this? Is there anything besides the heater core that can go wrong? Can a core fail without leaking? I don’t want to tear into this thing and replace the core unless I’m pretty sure that’s the problem. Thanks

 

[hatzie]

The heater core is supposed to separate the inlet and outlet. Some have the inlet and outlet on opposite ends but most just have at least one separator plate in the middle of the tank on one end... some have more than one on both ends so the coolant flows back and forth across the heater core a couple times.
I've had several vehicles stop heating because the coolant was mostly bypassing the heater core through holes in the separator plate.

 

[Snoots]

Check this out . . .

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[PrairieDrifter]

Make sure your temperature blend door is operating properly.

 

[Shorty81]

Also make sure your heater hoses are routed correctly. If not you will not get correct flow to core.

 

[rwljpl]

Thanks. I’ll check the hoses and blend door before replacing the core.

 

[73c20jim]

Can you make your ac warmer???

 

[rwljpl]

Good question. I’ll check on that. If I can, does that means it’s the blend door?

 

[MikeB]

What do you mean by "not working"? Does it not even blow air on the floor?

 

[rwljpl]

It blows air. It just never gets hot.