How do you change the heater core in a 2004 Chevy Trailblazer with V6?

Answer 1

well my friends, GM has really stuck it to mechanics on this 1. start with battery disconnect, and don't hook it back up till you get EVERYTHING PLUGGED BACK IN. oh before you do the battery adjust the seats where all bolts are accessible. remove front seats, the book doesnt say this but youll thank me, considering whats ahead its a minor step. remove console. use a torx bit on the shifter, knob, tube and leather boot all come out as 1. disconnnect harness at back of console, youll be familiar with the coupler from the drivers seat. remove A pillar mouldings, remove long trim piece around defroster ducts. remove trim below steering column. remove steel knee breaker under column. rmv bolt connecting shaft to column. (inside car) disconnect big column harness with 7mm socket, discon airbag connector right next to it. remove 4 nuts and set column aside. remove trim panel around instrument cluster. remove instrument cluster. remove glove box cover. Scared yet? don't be, its just a big piece of GM junk.remove radio and a/c controls. NOW looking around the dash youll see a bunch of 10mm headed bolts that hold the plastic part of the dash to the steel framwork underneath it. that frame is called the I/P carrier. remove them, and don't forget to get the 2 by the passenger airbag. by now youre unplugging stuff as you go so im not gonna tell you anymore. the passenger airbag stays with the dash, so leave the bolts with the big washers alone. ok got em all? start tugging and undoing the harnesses, antennae wires, ductwork, and...viola! hey honey look what i got! she gasps and wonders if youre gonna get it all back together, cause youre already about 5 beers in. Relax its gonna be okay. pop open another 1 and marvel at your work. now youll see the I/P carrier and a bunch of harness plugs hanging out everywhere! that big black box from the middle over is your quest. that's the HVAC case, and yes you need to get the freon out of there responsibly.

remove metal bracket in middle frome carrier to console bracket. the console bracket needs to be unbolted to achieve this. the ebrake lever pretty much stays solid in the car the whole time. now remove the little blower motor for the back seats. right there in the middle of the car on the bottom of the case. man that a big pile of parts u got! but were so close now. the I/P carrier is next, big 15mm headed bolts on both ends, 4 around the column support, And a bunch of 10mm nuts holding the hvac case to the carrier. i shouldn't have to tell you to undo all the harness anchors. youre a pro by now and not even waggoner and his army of inbred engineers can stop u now. you have the power of 10 grinches! remove I/P carrier. there is NO studs holding case to firewall. unhook ac lines under hood, and cuss those stupid clips on the heater hoses. spray em with WD40 and pop another cold one. let em soak a minute and dig those nails in one side at a time, you can rotate the hoses somewhat, keep trying,POP got the first one didnt ya? do the other 1 now. that's so our overpaid UAW workers don't spend too much time putting cars together. to heck with the poor sap who has to undo them. wash hands, get back inside. unplug 3 actuators on left side and 1 on far right, PAY CLOSE ATTENTION to how the harnesses run around the case! Remove hvac case. flip it over and remove those 5.5mm screws holding the heater core cover on. remove heater core! congatulations, you now are qualified to work on any GM piece of crap out there. OK when ya get it back together, THIS IS IMPORTANT, after reconnecting battery and turning the key on, DONT JACK WITH A/C controls for about 90 seconds! the system will go thru a self test mode. leave it be while it does this! by the way the book gives 10.3 hrs on this, did my first 1 yesterday, i was draggin ass a little, took me 7 hrs. believe i could do the next one in 4. i hope theres never a next one. I posted this cause i was looking for answers yesterday and could find none. so good luck and keep wrenching.

i just did my sisters heater core in her 2003 trailblazer ltz and this guys information guided me thru almost to the t. he is pretty dead on about his information.