The heater does not blow hot air when I let my Toyota Tacoma 2007 idle in morning for 15 minutes. The outside air temperature is about 24 degrees, the heater blows air that is light warm. Is this normal. I have already replaced the thermostat and water pump, but same problem persists?

Check for a blocked/kinked heater or heater return hose as well as the heater core itself NOTE:-Be careful do not spill any antifreeze on the ground it is deadly to animals that lick it

I had this same exact issue last month. My anti freeze was low. Once I filled my antifreeze, all my issues stopped. Now I can idle and my car stays blowing warm air. Hope this helps.

I am having the same exact problem with my 2005 Tacoma. Two different mechanics have checked it and both told me I probably had a small leak and needed to replace the head gasket. They said I was getting combustion gas in the cooling system.