Heater core should be behind glove box. Remove glove box and screws( approx. 8) that holds cover in place. Pop hood and look for two hot water lines running into firewall at that location(passenger side) Remove lines by loosening hose clamps(advisable to replace) Remove heater core from inside and replace.
You have to drop the steering column and pull the dash. Then after locating the heater core case below windshield you have to cut out a piece with a Dremel. After replacing the heater core you have fun putting everything back together..(use plastic weld to seal the case back up).in other words don't do it yourself it is a huge pain.
NOT AN EASY JOB all of the av ducts have to come out from under the eash. Get a manual on your car and it should have pictures.
my 86 is about the same and i took out the screws of the glove box and started on the dash board screws then loosened the bolts on fire wall which is the heater core back, the bolts on the right i had to cut off with a mider saw very rusty. take off the cable under the hood left side and pull heater core box out disemble and put in a new core for 26 dollars and redoo.
Sounds like 1: the heater core was never fixed or 2: the coolant system wasn't filled and purged properly. if the car is loosing coolant and overheating i would check the heater core. if its low on coolant or has air in the coolant lines you wont get any heat either.
If one is rusted you might as well replace them all and that requires removal of the engine
86
80-86 Full size Bronco 80-86 F150, F250, F350
its not that hard,it took me about 4 hrs to remove and install a new one you do not need to remove the dash,just a little tight to get a socket in there a number 7 socket is all you need. good luck
The heater blower motor is under the hood bolted to the heater plenum on the passenger side of the car.
To replace the injectors in 86 Toyota truck 22r, simply refer to your user and service manual.
As with most vehicles, with coolant reservoir full, engine running, warmed up and hood open, feel the heater hoses with your hands. If both hoses are luke warm or cold, you may need a new thermostat. If one hose is hot and the other is luke warm or cold, the heater core is probably plugged up, in which case you can try flushing the heater core. If both hoses are hot, you probably have a problem with the temp blend door in the HVAC system behind the dash assembly.
check and see if the thermostat been removedcheck to see if the heater core has been bypassed. if the heater core was leaking at some time in the past, the previous owner may have bypassed it (with a 2 dollar hose bypass kit) instead of actually fixing the leak. this was the case on my 1990 xj6.