Heater core replacement 88 s15 - 1988 GMC S-15

Have you replaced the heater core? If not, most likely the reason the previous owner bypassed the heater core was because it leaked. I will be happy to send you photos of how the hoses attach but I will need your email address.

Here's a link to replacing your heater core. Repair Guides Heating And Air Conditioning Heater Core AutoZone com

wow big job, ok here we go, cold engine drain cooling system,loosen clamps and disconnect hoses from core plug ends, under hood, now inside remove right side under dash panel,remove heater floor outlet duct,remove screws and clips that secure core cover,remove cover then core retaining straps and core reverse to put back together

well either your heater core lines are clogged ore the heater core is just bad

Here's a link on how to replace heater core.

A heater core replacement on any vehicle is a very hard job. It would most likely involve taking the whole dash out of the car just to reach the heater and then you would have to open the heater box just to get to the heater core....If you have never done it before I would take the car to a service or repair center of your choice (it doesn't have to be a dealer). The money you spend will give you peace of mind because the job will be done correctly and if it gives you trouble, you have a warranty to fall back on. Much good luck

Remove and replace heater core, pre Mitchell labor guide is 5.9 hrs, does not include recover, evacuate and recharge a/c system, to remove heater core, that should be about another 1.4 hrs, hope this was very helpful.

Behind the dash. You will have to pull the whole dash assembly. It looks like a little radiator.

disconnect negative battery cable
remove coolant reservoir
dis-connect heater hoses at heater core
remove mounting screws and nuts from the heater housing in the engine compartment
remove glove box door and liner
disconnect heater controls ( be sure to lable them so you know where to put them later )
disconnect the computer ( ECM ) an mounting bracket
remove the radio antenna cable
remove the kick pannel and detech the right lower corner of the dash pannel.
pull the heater assembly to the rear for access and dis-connect the wiring harness
remove the screws and nuts retaining the heater housing inside the cab
remove the heater housing from the vehicle
detach the core retaining straps
and wala you got it
to install it just reverse these steps.
good luck