Heater wont work

[bigsharks6]

i have a 2001 z71 5.3 and when i turn the control knobs to the heat, it blows only ac, just replaced resistor. what else can it be?

[j cAT]

Originally Posted by bigsharks6

i have a 2001 z71 5.3 and when i turn the control knobs to the heat, it blows only ac, just replaced resistor. what else can it be?

both hoses to the heater core must be hot ... if they are not both hot, it is clogged...did you ever blow/flush out the heater core ???

[bigsharks6]

not yet i found the other post a few pages back im going to check everything that was reccomended there today.

[kahjdh]

see if your blend door actuator is moving, mine sticks sometimes.

[bigsharks6]

Originally Posted by kahjdh

see if your blend door actuator is moving, mine sticks sometimes.

how do i do this?


both hoses are hot, i dont hear anything happen when i turn the controll from cold to hot, so im thinking eaither that door is frozen (after all im in south texas and it really never gets below 50) or there no power getting to that door. how do i start checking this?

[j cAT]

the heater hoses both hot going into the fire wall means coolant is flowing in the heater core...

as mentioned before the temperature blend DOOR is not working...this is a step motor that has 5volts dc applied to it and this motor moves this door to allow air to pass thru the heater core....this door can stick,,,maybe is loaded with texas dust....out here where I'm at it would be leaves,and pine crap...

so this means you must open the air box under the dash directly above the center trans hump,,,this is where this motor and then the internal door can be checked out...


you got filters in that air box,,,if not all the greater chance for this to occur..................

[bigsharks6]

Originally Posted by j cAT

the heater hoses both hot going into the fire wall means coolant is flowing in the heater core...

as mentioned before the temperature blend DOOR is not working...this is a step motor that has 5volts dc applied to it and this motor moves this door to allow air to pass thru the heater core....this door can stick,,,maybe is loaded with texas dust....out here where I'm at it would be leaves,and pine crap...

so this means you must open the air box under the dash directly above the center trans hump,,,this is where this motor and then the internal door can be checked out...


you got filters in that air box,,,if not all the greater chance for this to occur..................

whats the best way to access this? do i need to start removing the dash and what not? or can i access it like i did the blower resistor.

[bigsharks6]

Originally Posted by j cAT

the whole dash must be removed,,,this is a real PITA....

doh not what i wanted to hear... k i will wait untill this weekend to work on it... here we are in the worset drought ever, and it is finally raining after 9 months of not a drop of rain....

[j cAT]

Originally Posted by bigsharks6

doh not what i wanted to hear... k i will wait untill this weekend to work on it... here we are in the worset drought ever, and it is finally raining after 9 months of not a drop of rain....

that post that stated the dash,,, must be removed is not correct ,,,,I made a mistake ,,,,it is possible to get to it by removal of the plastic directly over the hump area of the ducting...you will see when you open this area up not too hard...

[bigsharks6]

Originally Posted by j cAT

that post that stated the dash,,, must be removed is not correct ,,,,I made a mistake ,,,,it is possible to get to it by removal of the plastic directly over the hump area of the ducting...you will see when you open this area up not too hard...

i have bucket seats in the truck, so would i be removing the plastic console, like where the tape player is, around that area? what is the part called so i can search it online so i know what im looking for.

[j cAT]

Originally Posted by bigsharks6

i have bucket seats in the truck, so would i be removing the plastic console, like where the tape player is, around that area? what is the part called so i can search it online so i know what im looking for.

I have the same console in the middle ,,between bucket seats...

temperture door control...you most likely will find debris in there interfering with the door..most likely that door never sees the movement to the heat mode position where you live..