heater question

[tomford]

I recently picked up an 87 k5. The PO said that he had the heater core replaced because it was getting foggy inside, when he got it back it didn't work and the garage said oh it never worked, sorry. Anyways i found the cable that changes hot to cold was not on, and on one of the blower doors the plastic piece was broken. Fixed both of those. The heater core does look new fish, blower motor and resistor look new. I replaced the T stat with a new one (195 deg.) the lines going to the core are hot, but it blows luke warm air. Any help would be great. P.s. it has AC


Thanks
Tom

 

[down4thakrown]

Make sure the arm that the cable connects to is moving? Those cables control where the heat or cold air goes. So if the arm don't move means door doesn't open to let heat into the ducts.

 

[80' 427]

Have you felt the hose temperatures?

 

[tomford]

Hose going into and out of the heater core is hot.

 

[80' 427]

So that means it is an air door problem

 

[campfire]

So that means it is an air door problem

This would be my first guess as well.

 

[tomford]

What's the best way to check and fix? Are there any good service Manuals around? I'm used to working on airplanes and the manuals tell you everything you need to know.
Thanks
Tom

 

[80' 427]

The best manuals are the GM ones.

 

[tomford]

Where can I get them from?

Thanks
Tom

 

[80' 427]

EBay.

 

[wheels87k5]

These are your other best friends.

 

[Blue85]

Just remove the glove box and you can see the end of the cable on top of the HVAC box. Maybe it came loose or is broken. If the cable works fine, take the front of the box apart to find the problem.

 

[tomford]

ordered the GM manuals, heat cable is attached, gets cold when moved to cold, luke warm when its on hot.

Thanks

 

[Metrodps]

Be sure the hoses are on the right way 3/4" hose to radiator or water pump and 5/8" hose to intake no matter what. The hose (from the intake manifold) should always be connected to the bottom of the heater core. As the coolant flows into the core it fills it from the bottom to the top (where the outlet hose is connected). This ensures that the tubes within the heater core are always full of water and any trapped air is vented out along with the coolant that is headed back to the engine.