Heat is not working. Blower works but just luke warm air

[Matt2475]

I'm not sure what to do I need some help!! My truck is a 85 Scottsdale

[zieg85]

First thing, feel both heater hoses.  They both should be as hot as your radiator hoses.  A bad or no thermostat would also cause lack of heat.  What does your temperature gauge indicate? 

[Boone83K10]

yep, check the thermostat. probably stuck open and won't allow it to heat up. if not that, then check your blend door in the heater box, might be mixing in outside air.

[Matt2475]

Both heater hoses are hot and the temp stays at about 185-190. I did a heater core Bc a mouse decided to make a nice warm home in the heater box. Let the truck heat up with the ratior cap off and I pretty sure all the air bubbles worked out.

[Boone83K10]

Did you check blend door operation?

 

[Beans]

I'm having the same problem... I changed the thermostat and both hoses are hot... I see the blend door idea but on all other forums I am seeing that it is only if you are getting good heat... am I not understanding that right..?  If the blend door is where I should be looking can you give me some more insight on finding it..?

Thanks in advance!


Beans
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[mcintyrederek]

I am reworking my '86 Silverado, so I have the interior taken apart.  See pics.  The blend door is behind the glove box.  The four or five screws can be taken out of the glove box bottom and removed and you can see the heater core cover and blend door actuator.

The blend door cable is like a choke cable or lawn mower throttle cable and hooks directly to your AC/heat control.  As you can see in the 2nd photo there is a slight adjustment with an 8mm screw head to move it back and forth a little.  Have someone turn your control from cold to hot and make sure the cable is moving and the actuator is operating.

[bd]

If the temp cable adjustment doesn't resolve it, remove the blower motor and check inside the heater housing for a rodent midden.

[Beans]

Thanks Derek and bd!


Beans
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[Beans]

So blend door seems fine... Removed the blower fan and found a bunch of insulation... acorns and a family of skeletons (mice)... Thanks for all the help!


Beans
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[roger97338]

I had mice make a home in my heater and ducting once too. Later, I read that dryer sheets will keep them away. Now, I keep dryer sheets stuffed under my seat and carpet, and if my pickup is going to be sitting unused, I tuck some into the lower heater outlet and defrost vents. No mice yet!