Heater core?

Hello,

You will need to start by disconnecting the battery and discharging your AC system.

Here are two guides and diagrams with the instructions below.

This will give you an idea.

https://www.2carpros.com/articles/replace-heater-core

Here are the AC instructions:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Check out the diagrams (below). Please let us know if you need anything else to get the problem fixed.

Cheers

Hi.
Changing the heater core on your vehicle is an involved procedure. It is located under the dashboard on the passenger side and requires much of the dash to be removed. What I would recommend is that you get a manual for the vehicle. It will provide step by step instructions with pictures to help identify parts.

I would send you the directions, but I am unable to cut and paste from the service manual we use.

If you get a manual and still need some help, let me know. I will be happy to help.

Joe

If it is going to work for you playing shortcut do it, but remember if it is not done right, you will be going back in.

Sounds like it has a partial restriction. Try having a radiator shop backflush it to free up the clog. Dont use a garden hose, the core can start leaking from too much pressure and you dont want to have to replace the heater core in that Blazer, the entire dash has to come out

Hi, replacing the heater core is an involved process. You need to remove part of the dashboard. I recommend purchasing a manual for your car. It provides step by step instructions and pictures to help identify parts. I am unable to copy and paste from the online manual we use, and there is too much room for error if I try to explain it via the Internet.

Removal & Installation ("C" & "K" Series)
Disable air bag system.
Disconnect negative battery cable.
Remove glove box by squeezing sides together. Remove 2 instrument panel retaining bolts from glove box opening.
Remove center floor duct.
Remove center support bolt.
Remove Electronic Control Module (ECM) and tray. Remove both kick panels.
Remove blower motor cover and blower motor.
Remove driver's lower instrument panel cover and knee bolster.
Lower steering column.
Remove instrument panel left and right pivot bolts located at lower corners of instrument panel. Remove 3 screws from defrost vent, near windshield. Disconnect any connectors and tilt instrument panel back far enough to access heater case.
Remove coolant recovery reservoir from engine compartment.
Drain engine coolant. Disconnect heater hoses at core.
Remove bolts and nuts from engine compartment attaching heater case to vehicle.
Remove heater case.
Remove 7 screws attaching heater case cover plate. Remove screws and bracket attaching core to case. Remove heater core.
To install, reverse removal procedure.
Replace any seals.
Fill cooling system. Start engine and check for leaks.

Removal & Installation ("S" & "T" Series)
Disconnect negative battery cable.
Drain engine coolant.
Disconnect heater hoses at core.
Remove instrument panel. .
Remove air inlet assembly.
Disconnect vacuum lines to heater case components. Remove heater case retaining studs from engine compartment. Disconnect blower motor resistor. Remove heater case. Remove heater core access cover from top of heater case. Remove heater core. Remove seals. To install, reverse removal procedure. Fill cooling system. Replace old seals with new seals. Start engine and check for leaks.

Most likely an air pocket not allowing coolant to reach the heater core lines. Run the vehicle until it reaches around 200 degrees, that will allow the thermostat to open. Then let it cool off for a while before checking the coolant level. Add as necessary.

Believe me, this is not something that you even want to attempt. This is a major undertaking. Even for an experienced tech, this is about a ten hour job.

This involves removing the entire dash and part of the fender to get this apart. There are many experienced techs that will not attempt this.

I could not have said it better myself. Wrenchtech is 150% correct with this one. The book time give 8.9 hours. That is giving a professional tech is doing the job. I have done a few, and hated each one, haha. Keep in mind, before the dash comes out, you need to disable, and remove the air bags, one wrong move, and they may deploy causing serious injuring. Leave this job to the professionals.

https://www.2carpros.com/articles/car-cranks-but-wont-start

You need to find out what is missing causing the non starting.

It could be that your hvac control head is bad. Remove it and see if any of the connectors are melted. Then check to see if your blend door actually moves. Your cluster may need replacing. Check to make sure you got all the connections in the right place and and check fuses.