heater controls "off"
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Freshman User
Joined: Dec 2005
Posts: 26
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heater controls "off"
my 1988 f-150 heater controls are "off",when i set it on defrost it works through the defrost and floor,when i set it to mix,it works through the floor and when i set it on floor,it works through the panel vents. i can't get it to work on defrost only. This isn't a big problem but i would like to get it right....is this a vacuum problem or is the cable that controls the settings somehow misaligned?
Posting Guru
Joined: Jun 2004
Posts: 1,781
Likes: 1
From: Central NY
Not sure on an 88 but its usually vacuum controlled and it sounds like they have been misconfigured. This happened on my wifed Olds a while back. Identify the main vacuum line and label it. Pull the remaining vacuum lines off the controller and have the following labels ready Defrost, Floor, Vents. (I'm not sure if you'll have a defrost line since 'no vacuum' defaults to defrosters.) Next turn the fan on high and use the main line to supply vacuum to the remaining lines and see where she blows from. Label the line properly and when all are labelled, reattach the mainline to the controller, turn it to floor and feel which remaining port now has vacuum. Next do dash/Vent. Last is defrost, if there.
Hope this helps
Tim
Hope this helps
Tim
Senior User
Joined: Sep 2004
Posts: 484
Likes: 0
From: SC lowcountry
I'd look for vacuum leaks before disturbing the harness - since the defrost position gives you defrost and floor, poor vacuum could easily give that result. Look at all the plastic vacuum lines in the engine compt first, for signs of deterioration; the white one at the outside/recirc actuator on top of the heater/evaporator housing is especially prone to crumbling once you move it. Replace with a section of rubber vacuum hose that fits outside of plastic.
