The question you ask is too involved for a proper answer. You need to go to a car parts store, and get a repair manual for your car. They cost about $16.00 Or, go to a Public Library.
To install the heater control in a Honda Passport, first, disconnect the battery to ensure safety. Remove the dashboard trim surrounding the heater control unit, typically using a screwdriver or trim removal tool. Then, unscrew the heater control unit from its mounting and carefully disconnect the electrical connectors. Reverse the process to install the new unit, ensuring all connections are secure before reassembling the dashboard.
you should only have to take loose the heater hoses where they go into the firewall and of course the heater core itself
A "heater" or a "heater core"?
Locate heater control valve in a 2001 Honda civic
Buy a Toyota
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The heater in the CRV Honda is not working . How do I fix this
how replace the ABS control for Honda pilot 2004
replace it
If the charging relay in your Honda Passport is not functioning and there's no heater output, it could indicate an issue with the relay itself, a blown fuse, or wiring problems. Check the relay for continuity and replace it if necessary. Additionally, inspect the fuses related to the heating system and charging components, ensuring they are intact. If the problem persists, it may be wise to consult a professional for further diagnosis.
Replace Thermostat
remove and replace.