Your Mazda 626 uses a heater coil which has tiny appendages for increasing its heating surface. The air is heated as it passes through the coil and is delivered to the cabin by way of the vehicle ventilation system. You can tell that the heater coils needs replacing whenever you smell a sweet sugary scent coming from the heater. If the cabin is receiving air but not heat, this is another sign that the heater coil needs to be replaced. The replacement procedure can be time consuming, but you can perform this job yourself and save a great deal of cash.
Access the engine and remove the negative battery cable using a ratchet and socket. Set a drain pan beneath the radiator. Drain the radiator by removing the drain plug with a ratchet and socket.
Notice the heater core on the passenger side of the engine on the firewall and pull all hoses from the heater core. Remove the heater inlet and outlet hoses from the firewall by loosening the hose clamps with a flathead screwdriver. Insert rubber hose plugs into the ends of the hoses to prevent leaking.
Access the vehicle cabin and remove the ashtray and ashtray bracket. There are four screws in the wall behind the ashtray. Remove them with a Phillips screwdriver. Then unscrew both sides of the dashboard with a ratchet and socket. Pull the panels out by hand. The air conditioner shield is now visible. Pull it out, as well as the cover spring for the heater coil. Open the temperature door and lift the dashboard's cover. Then remove the cover with a ratchet and socket.
Push the dashboard cover back and remove the heater core by unbolting with a ratchet and socket. List the heater core out as an assistant holds the dash up.
Install the new heater coil with a ratchet and socket. Replace the dash cover and close the temperature door. Reinstall the cover spring for the heater coil as well as the air conditioner shield and both sides of the dash. Screw the four screws back into ashtray wall and reinstall the ashtray bracket and ashtray. Reattach the battery cable.
