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Heat blows through defrost

 
Old 01-23-2019, 11:06 PM
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Red89'-L98
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Default Heat blows through defrost

So finally got my heat fixed on my 1989, at least so I thought. Found and changed a bad blend door motor causing me to only have A/C no matter what. Get the motor changed and finally have heat. However, the heat will only blow through the defroster vents and nothing else. My A/C when set to 60 has no problems and goes through normal vents but once set to anything else it goes to the defrost vents. Let me know what you guys think I should start with. Thank you.
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Old 01-23-2019, 11:42 PM
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Im not sure of your year but this 3 way and the heater vacuum line must be hooked up. Defrost is default.
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Old 01-24-2019, 02:40 PM
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to see the three way at location HVAC on the above diagram, you may need to pull the dizzy to see it. mine hand broken there. i spliced a small piece of rubber tubing i think it was 5/32 ID and it worked great. i had to peel back my harness that runs behind the engine (all doable with dizzy pulled) to find the piece fo broken vac line.
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Old 01-24-2019, 03:28 PM
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Old 01-25-2019, 09:09 AM
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Originally Posted by Red89'-L98 View Post
So finally got my heat fixed on my 1989, at least so I thought. Found and changed a bad blend door motor causing me to only have A/C no matter what. Get the motor changed and finally have heat. However, the heat will only blow through the defroster vents and nothing else. My A/C when set to 60 has no problems and goes through normal vents but once set to anything else it goes to the defrost vents. Let me know what you guys think I should start with. Thank you.
I've had the same problem. Mice had chewed vac lines in back of the controller
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Old 01-28-2019, 07:57 PM
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Originally Posted by Cruisinfanatic View Post
I've had the same problem. Mice had chewed vac lines in back of the controller
I feel like this might be my problem. I canít seem to find my manuals due to a recent move but the controller is by the driver side kinda behind the gas pedal correct?

Also I just noticed something else. Whenever I switch the Head unit to heat (90į) it blows nice cold air out of it trough the defroster and when the unit is set to cold (60į) it blows heat through the normal vents.... anyone got any ideas on this? Iím thinking either the head units is messed up or the person who rebuilt the motor for the blend door screwed up and wired it backwards. Iím thinking I could de-pin the connector and swap the wires around if so. Any thoughts?

Thank you all so much for the help thus far!
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Old 01-30-2019, 10:17 AM
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Originally Posted by Red89'-L98 View Post

I feel like this might be my problem. I canít seem to find my manuals due to a recent move but the controller is by the driver side kinda behind the gas pedal correct?

Also I just noticed something else. Whenever I switch the Head unit to heat (90į) it blows nice cold air out of it trough the defroster and when the unit is set to cold (60į) it blows heat through the normal vents.... anyone got any ideas on this? Iím thinking either the head units is messed up or the person who rebuilt the motor for the blend door screwed up and wired it backwards. Iím thinking I could de-pin the connector and swap the wires around if so. Any thoughts?

Thank you all so much for the help thus far!
The controller is under the radio. You know, the controls for heat and air?
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Old 01-30-2019, 02:28 PM
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Originally Posted by Cruisinfanatic View Post
The controller is under the radio. You know, the controls for heat and air?
I was talking about the portion with the vacuum lines. Isnít there a box of some sort near the gas pedal with them? Or am I thinking the entirely wrong vehicle lol
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Old 01-30-2019, 04:02 PM
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did you confirm posts three and four above are not your problem?
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Old 02-06-2019, 03:32 AM
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Post 3 and 4 are not my problem from what I can see. I have a good vacuum between the lines. Check with a vacuum pump and holding psi

I Now realize I was confusing the programmer and controller in my head.... sorry about that.

I found that the motor i was sent was wired backwards as swapping the pins in the connector fixed that problem. Still doing some work and trouble shooting on the defrost problem. Just got back from a trip so havenít had time to play with it.
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