Where is the block heater cord on a 2004 Pontiac Montana?

Question edited for clarity.
Question moved to model category.

There is help and videos.

https://www.google.com/search?q=2004+montana+remove+throttle+body

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You can scan the controller.

Hello,

Back of block by firewall?

Heater hose--heater core.

Freeze plug

I hope this helps.

put in a radiator flush ,run it for 20 miles it can be a blocked core in both the radiator and the heater.that should clean it. then refill with a 50/50 mix anti freeze then bleed it of air. put your heater on full .run the engine on tick over.then push in the radiator hose to push the air out of the expansion bottle cap .it is off . then refit your cap.

hope it helps

could be anywhere since they are owner installed but usually through grill or under hood

First off make sure the thermostat settings are set the same on the control panel for both front and rear units if thats ok it could b a few possibilities. 1 pluged heater core in rear 2 blocked heater hose try looking into these and see if it helps any

THE 97-04 MONTANA HAS THE 3.4 ENGINE WHICH HAS AN ISSUE WITH FAULTY INTAKE MANIFOLD & HEAD GASKETS WHICH FAIL TO SUSTAIN CIRCULATION IN THE COOLING SYSTEM AND CAUSE AN INAEQUATE HEATING SITUATION. REPLACE WITH FELPRO GASKETS AND YOUR PROBLEMS ARE OVER, PROVIDING ENGINE IS NOT DAMAGED!

CHECK THE HIGHT OF THE HEATER MATRIX IN THE CAB , IF ITS HIGHER THAN THE FILLER/EXPANSION TANK. THEN ITS AN AIR LOCK, LOOK FOR THE HIGHEST PIPE AND SEE IF THERE IS A BLEED VALVE, IF NOT TAKE BOTH PIPES OFF THE MATRIX FEEDS AND FLUSH OUT TO SEE IF IT IS BLOCKED, AND RECONNECT LOWEST PIPE FIRST AND FILL SYSTYM TILL WATER APPEAR FROM TOP AND RECONNECT RUN MOTOR, AND KEEP TOPIN UP

There is a mix damper inside your duct that controls the heat over heater core and ac evaporator that to your floor and one to your defrost. it is probable an electric actuator, that is not functioning properly. If yu can locate it and manually move it, you might have to remove the actuator motor first, you should be able to figure out your problem, I hope this helps! merry Christmas!