I don't know why the vent would not open for the defrost, but it may be related to the fact that your heater core is blown. If your getting nothing but cold air out of the vents when the heat is on, your core is finished and if the core is finished then it is likely related to your vent not opening/switching. Something''s wrong with your heating either way.
near the fire wall where the heater hoses enter
Go to advanceautoparts.com and enter your vehicle's info. Search for heater core and it will show you a pic. Mike
If you mean using a window AC and installing it backwards so it rejects heat indoors, no and yes, no it does not initially, however as an AC unit has no defrost cycle, eventually the outdoor coil will frost and require defrosting, if this is not done, conceivably liquid refrigerant could enter the compressor and damage it.
In most cases no. The core flows both ways.
Re-prime the siphon
Yes, then you can control the robot and crash him into asteroids until the robot blows up
remove the four nuts in the engine bay on the heater box near where the heater core hoses enter. Drain coolant remove the hoses and pull the heater box out from the inside of the car. Remove clips holding heater core, than put your new one in.
In the dash. You can see 2 hoses to it enter your firewall. Right there.
Use the defrost button on your microwave and enter 600. On the display it should say 6.00 for 6 pounds of food. Then press start. Answer 2: Defrost in the refrigerator for about 48 hours.
You have either a cracked heater core or bad heater hoses that are allowing antifreeze to enter into the vehicle............
Remove the glove-box door. Behind that is the heater core cover on the interior, passenger side of the firewall. Remove that cover and there is the heater core. Open the hood and look where the heater hoses enter the front right passenger area of the exterior side of the firewall. Disconnect the two heater hose clamps and you can then remove the heater core.
The match!