Toyota 4Runner 1984-1995: How to Repair Heater
Has your heater quit on you, leaving you in a deep freeze this winter? This article will show you how to diagnose and fix the problem to get hot air blowing out of your vents once again.
This article applies to the Toyota 4Runner (1984-1995).
So, your heat has gone out and you have checked the usual suspects. The blower motor is working, the vent controls are all functional and no fuses are blown, what gives? Unfortunately, it sounds like your heater core just gave out. The heater core is part of your engine's cooling system, imagine it as a box situated behind the dashboard that has hot engine coolant passing through it. When you crank up the heater, the blower pushes air past the core and into the cabin. Symptoms of a heater core gone bad are twofold and terrible: first, the heat no longer works, and second, you may have found a sweet, wet substance in the passenger-side footwell. The sweet smell is the smell of engine coolant leaking out of the heater core. If left unattended, the car will continue leaking coolant and eventually overheat. If that sounds like your truck, let's fix it.
Materials Needed
- Ratchet
- Assorted, common size sockets
- Flat head screwdriver
- Radio installation keys (optional, but helpful)
Step 1 – Remove the dash
Begin by removing the glove box, then pull out the small trim piece located underneath the stereo and set both pieces aside. Move over to the driver's side of the cab and pull out the trim piece underneath the steering column. Detach the hood opener cable. Pull out the upper left vent.
Figure 1. Remove the glove box. 
Figure 2. Remove stereo trim piece. 
Figure 3. Remove steering column trim.
Remove the trim piece that goes around the radio and climate control panels, then remove the knobs for the climate control. Pull the stereo out. Remove the instrument cluster. Unscrew the four bolts (14mm) that hold the steering column to the main dash support and let the steering column drop down to the driver's seat. Pull the dash out.
Figure 4. Remove the stereo/climate control trim ring, climate control knobs, and stereo. 
Figure 5. Remove the instrument cluster. 
Figure 6. Remove the four bolts holding the steering column to the main dash support brace.
With all of that done, the dash should now be free. It may require some fiddling to get the dash up and over the steering column, so take your time here. Dash removal commonly results in a cracked dash, which is heartbreaking(ly expensive).
Step 2 – Replace heater core
Remove the two supports for the stereo. Remove the two fasteners and the two nuts as well as bolts on the support bar on the passenger side, then pull the bar out. Remove the air duct between the heater core and blower motor. Remove the heater core and install the new one in its place. It's a good idea to also replace the weather stripping and gasket when you swap in the new core.
Figure 8. Remove the stereo supports and passenger side support bar. 
Figure 9. Remove the air duct between the blower motor and heater core. 
Figure 10. Install the new heater core.
Step 3 – Reinstall dash
Reinstall the duct between the heater core and blower motor, then the passenger side support bar and stereo surrounds. Slide the dash back in reconnect the steering column to the support bar. Reinstall the instrument cluster, stereo, climate control knobs, and surrounding trim piece. Replace the upper left vent, reattach the hood cable, and the bottom trim piece of the steering column. Reinstall the bottom stereo trim piece and the glove box.
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