jukeboxtango

hello everyone

i have a grand jeep cherokee ltd 1997
my heater has started to blow cold air only,even when i select high temperature.my coolant level is fine and the air blows through whatever vent i choose on the heater controls.
my tempeature in the engine remains constant and both my radiator hoses get hot when the engine reaches temperature.
i get tepid heat eventually when i select the floor option in the heater control panel, butstill cold air when i select demist.
i can hear the blend doors opening and closing so i dont think they are the problem
its just strange warm air at floor level and cold air at demist
i have tried running the fault code on the azc and it says 00
any help greatly appreciated

Hommersimpson

im takin a guess..... sounds like the blend door is broke...

jukeboxtango

i can here the blend doors opening and closing

jukeboxtango

nobody any ideas ?

DemonGrinder

are the hoses (coming in and out of the firewall to the heater core) both the same temp ?

jukeboxtango

Both are hot feel the same temp

jukeboxtango

surely there are experts out there who can share there wisdom with me who can help me ?
would disconnecting the battery do any good ?
would it maybe reset the system ?

ToyComa

just because you can hear the blend door working doesnt mean it is working properly.

91cavgt

Exactly. I have worked on big trucks where you could hear the blend door moving, but there was no heat. I got to where the blend door was only to find that it had broken off the hinges and was basically stuck in the A/C position. You could hear it move, but it wasn't moving enough to redirect air over the heater core.

My advice would be to get to the heater core and;

1. confirm that the blend door is working correctly and

2. confirm that nothing is blocking the flow of air over the heater core

skookxj

yes, you can still hear the blend door,that doesnt rule it out as the prob........doesnt sound like your HCV is stuck shut or anything but to have heat on botton n not top...sounds like its interior block somewhere...

jukeboxtango

i have tried running the fault code on the azc and it says 00
would it not show a fault if it was the blend doors ?
i'm really just hoping it would be a cheap fix ?

jukeboxtango

if i removed the blend doors would i get heat but no aircon or visa versa
trouble getting doors for a 1997 grand cherokee ltd rhd

ol"blue

The control unit (with the *****) on that system is prone to failure. It should show a code when running the system diagnostic though. I'm on a lap-top so can't send you scans of my manual. If you don't have a FSM, pick up a Haynes (they're cheap) and it'll show the procedure.
Dan

jukeboxtango

when i run the diagnostics the code says 00
its -4 oC here no heat
help would be appreciated

jukeboxtango

when i run the diagnostics properly the code says 23
is there any diagrams or tutorials out there to fix this fault
can someone explain to me in simple terms what a blend door does
i have atc