Having problems with your 1998 Ford F150 Regular Cab ?
Defrost blows cold air
\015 Floor vents blow hot but panel and defrost blow cold to luke warm air . this seems to change with engine rpms some. more rpms more warm air.already changed the thermostat. thought maybe it was vacum somewhere but dont know where to look.can you help\015
Sounds like you have a plenum door that is not opening when you go into defrost mode. You will have to check all your vacuum hoses and switching valves under the dash to see which one is not working. Hope this helps.
Repair Help & Product Troubleshooting for 1998 Ford F150 Regular Cab
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