Heater only blows cold air

So, my truck from Hell that I just bought has another issue today. Its a 2001 Tacoma DC Prerunner 4wd converted A/T 3.4L. I only drove it once for a test drive a couple of weeks ago, loaded it onto my trailer and it has been in my garage since then while I have been fixing issues with it. I do not remember running the heater during the test drive. I believe I did and I'm pretty sure it blew warm air but again, I am not positive. So, the truck had green antifreeze in it. I started a system coolant flush process today. Drained the block and the radiator. Filled with a couple gallons of distilled water and started the truck to get it up to operating temperature. I put the temp control dial to full hot and turned on the blower. It will only blow cold air. I looked under the dash and noticed that the cable actuator is working fine when I adjust from cold to to hot and the valve on the firewall it opening and closing as well at the other end of the cable. Please tell me there is something simply I am missing and this is not a failed heather core problem?

 

next step would be to disconnect the heater core lines off the motor--preferably just one(50-50 shot!), and see if the motor is pumping coolant through it. i was told that pushing an air compressor through the lines is a bad idea, as the newer heater cores are so thin that they can sometimes pop doing that with extra pressure.

 

If it worked before the flush you likely have an air bubble and need to bleed the system.

 

One way to check without disconnecting the hoses to the heater core is to feel each of them first. They should both be hot if everything is working properly.

Also, try driving around and see if it blows hot air when you're driving. If it starts blowing hot air when you're driving but goes cold when stopped, you have air in your system. Places like AutoZone have bleed kits that are very simple to use.