Hi Scotty,
I have a 2004 Toyota Highlander V6 4WD with 180k miles in NYC. Coolant changed 5 years ago at 150k. No overheating issues. AC works great, when I turn the AC button off, I see a noticeable difference between cold AC and just cold (without AC button pressed). When I turn on the heat nothing happens, it just stayed cold in every mode. Coolant level ok, both heater hoses going into the cabin are hot. No specific clicking noises when I turn the heat on, nothing happens. What do you think is the issue? Thanks in advance for your help.
Ciao, Stan
For my experience it's often the heater control. Now if you remove the heater control switch cover that you just pull out. You'll see there's a nut behind there and sometimes the nut gets loose so you can't actually turn the knob and it's as simple as just tightening that nut up. If that's not it then odds are the heater control switch itself. The electronic part is bad and it's not sending any impulse to turn into heat mode
