Disconnect the negative battery cable and properly drain the engine cooling system to a level below the heater core.
you have to take the dash easyout to get to the heater core box . Its a two man job and is not easy.
What are the steps to change the heater core on a 1991Chevy S10 pickup ?
To many steps to list here, would recomend purchasing a shop manual if you intend on replacing that heater core yourself.
Check your heater core and thermostat. The thermostat may be stuck open. Does the S10 run hot or cold?
Disassemble the dash and open up the HVAC compartment.
If coolant is leaking inside your cabin, you have a leak in the heater core. The only repair is to replace the heater core. Most auto parts stores sell them.
You need to remove instrument cluster. And the whole dash to access heater box. The heater box case has to be slpit in half to access heater core. A very timely and frustrating job. Take to a professional is what I recommend.
A replacement heater core would cost aprox $35.
Yes.
Not a fun job. If your looking to replace the heater core it requires removal of the entire dash and steering columm. I would suggest purchasing a shop manual for that vehicle to help you step by step thru the job.
The entire dash assembly needs to be removed to gain access to the heater core. If you want to do this job I would recomend purchasing a shop manual for that vehicle to help walk you thru it.
It is inside the heater core box behind the dash assembly. The dash assembly must be removed to gain access.