98 gmc jimmy the heat works great in defrost and vent mode but it will not switch over to feet mode it will just keep coming out of defrost checked for vac leak my feet freeze so I need it fixed any ideals what else it could be thanks.

 

There is a damper in the hvac plenum that brakes or sticks. Search for no heat i beileve its by a member with juice in his screen name. Its easy to fix.

 

yea i too am having the same problem. also. my heat/ac when in off position still comes out of the defroster vent at what ever speed the number is on (1-4).

 

i found this link. gonna try and make sense of it and give it a try

NO FLOOR HEAT 98 blazer - S-10 Forum

apparently it was a flaw in GMs design and wasnt made public or recalled...shocker lol

 

here ya go

https://blazerforum.com/forum/2nd-ge...or-heat-17808/

lots of pics and different takes on the fix.

 

thank you warthogdriver! at first i thought it was the actuator, now after inspecting it, it works fine and moves properly...so im thinking it is the blend door. so just so im clear...if it did snap off and break it would be at the bottom of the housing?