06 highlander hybrid heat doesn't come on until I get on the highway. Do anyone know what this could be? It blows cold air while warming up but not hot air.

Yes, dandyoun is right. The hybrid uses engine heat, just like any water-cooled car, to heat the cabin. But in the hybrid, there are electric heating elements in the heater core, to help hold heat when engine is not running and car moving. Also a ceramic-shrouded electric heat element in the dash for defrost, but still, it will take a few minutes. These electric heaters draw a lot of power, and operate off the same batteries and generating system that powers the car, and will be heated for only a short time if engine is not running. Regardless, there will never be instant cabin heat

Thank you both for your help I do have to check the antifreeze. I wanted to add that sometimes even after the engine has been running cool air blows out and no heat.

Thanks for bailing me out on that one ford nut. I didn't even catch that it was a hybrid.

Thank you!! I did need engine coolant but also seems to have a leak at the seam of my radiator. Once the engine coolant was filled I did have heat again.

Our problem is that when you switch from defrost to heat, all the windows immediately start to fog up. So bad, you have to switch back to defrost & roll windows down for a moment. Why would this happen?

When you switch from defrost to heat, a couple of things happen. First the A/C switches off, so you lose the moisture zapping power of the Air Conditioner, and secondly, warm air will hold more moisture than cold, so the increased humidity will fog up windows. Try leaving the A/C button on while switching to heat for a few minutes while windows warm up, that way the condensation won't form on a cold surface (your window). Once window is warm from heater, then all should be well. Also, if your heater core is leaking this will put a tremendous amount of moisture onto the inside of your windshield. Check for water/antifreeze dripping on to your carpet on the passenger side. Hope this helps.

I have the same problem however my coolant level seems fine. Any other suggestions?

If your coolant ever ran low for whatever reason, sometimes air can develop in the heater core. Try parking with the front of the car on an uphill slope, or jack the front up (don't forget those jackstands). Remove radiator cap (when cold), Run engine till warm (with the heater knob on dash turned all the way to hot (you don't need the fan on inside). once engine is warm, the thermostat will open completely, allowing any trapped air to hopefully work its way out. You may have to run the engine for a minute at a moderate rpm like 1500 rpms. Sometimes this will help get the air out. If there is air in the system, you will see bubbling out of the radiator, and the coolant level will drop. Top off radiator with engine off. Top off overflow resevoir as well, replace radiator cap, and allow engine to cool. Re check overflow resevoir as level may drop if there is residual air in system. Then take for a test drive. Hope this helps.

There is a hex nut under the dial that comes loose. Simply pull the heat/cool dial off, and you can tighten the silver nut with your fingers.

Guru9BT1's solution worked for my 2006 Highlander Hybrid, the nut under the temperature control dial was loose, problem solved!

I just picked up a 2006 and topping off the coolant fixed this issue. Thank you!!!

Thanks for the info regarding the low coolant level causing heater issues. Just looked like a genius to my new wife whose 2006 Highlander hybrid (243K miles) would blow cold air intermittently, usually (if not always) when the gas engine wasn't running. Other sites I looked at had me considering more complicated fixes. Glad I thought through it enough to realize none of them made sense and kept looking until I found this info!

The hex nut did the trick on my '06 HH. Last winter heat intermittently worked and this winter not at all. It was really that easy, it's now consistently hot and I was just getting ready to replace the heater core. Lifesaver!