Finding the heater core on 2004 pontiac montana

SOURCE: 2004 Pontiac Montana blows cold air in defrost

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!

SOURCE: Replace heater core in Pontiac Grand Am GT 3.4l

ram a sharp chissel or pointed head centre punch through the core and prise it out .,than tap the new one in place ,,,there u go bobs ure uncle

SOURCE: need to replace thermostat on pontiac montana van.

public library...Chilton or Haynes auto repair manuals or collisionrepairadvice.com     make sure you bleed the system

SOURCE: How do replace heater core in 2002 Pontiac Gran Prix

i do believe you have to take the passengers side dash apart behind the glove compartment. go to autozone and get a manual or go to the library and check the chiltons manual. this is not an easy job. how bad is the leak? if its not bad these heater cores are made of all aluminum. i would buy a bottle of that radiator additive and see if that takes care of the problem first. it only cost about 5 bucks a bottle and it may permanantly fix your problem.

SOURCE: How to remove heater core from 2000 Pontiac

Heater Core Cover Removal procedure
Remove the right instrument panel insulator. Refer to Closeout/Insulator Panel Replacement - Right in Instrument Panel, Gauges and Console.
Remove the left instrument panel insulator. Refer to Closeout/Insulator Panel Replacement - Left in Instrument Panel, Gauges and Console.
Remove the lower center console. Refer to Console Replacement - Front Floor in Instrument Panel, Gauges and Console.
Remove the console bracket. Refer to Bracket Replacement - Console Floor in Instrument Panel, Gauges and Console.
Remove the floor duct brace
Remove the floor duct

Remove the screws retaining the heater core outlet cover.
Remove the heater core outlet cover.

Remove the screws retaining the heater core cover.
Remove the heater core cover.
nstall the heater core cover.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

Install the heater core cover retaining screws.

Tighten
Tighten the screws to 1.6 N·m (14 lb in).

Installation procedcure

Install the heater core outlet cover.
Install the heater core outlet cover retaining screws.

Tighten
Tighten the screws to 1.6 N·m (14 lb in).

Install the floor duct.
Install the floor duct brace.
Install the floor duct brace retaining nuts.

Tighten
Tighten the nuts to 10 N·m ( 89 lb in).

Install the console bracket. Refer to Bracket Replacement - Console Floor in Instrument Panel, Gauges and Console.
Install the lower center console. Refer to Console Replacement - Front Floor in Instrument Panel, Gauges and Console.
Install the left instrument panel insulator. Refer to Closeout/Insulator Panel Replacement - Left in Instrument Panel, Gauges and Console.
Install the right instrument panel insulator. Refer to Closeout/Insulator Panel Replacement - Right in Instrument Panel, Gauges and Console.