No heat from Defrost

[Sixguns]

About a month ago the defrost in my 03 altima stopped with the hot air. The heat in my vents went south too. I bled the system for any air bubbles which didnt help and today did a flush of the system which brought a little heat back but only in my vents. When I switch back to the defrost it is still cold air but today when I was messing with the cool/heat switch I noticed that when I went to cold it got much colder. Is this just a switch problem that might be causing it? And if so, how do I fix that? I kind of know my way around a car but have limited tools and time. Trying to figure out quick since leaving for work at 5 am when its 10 degrees sucks with little to no heat on a 45 minute drive.

 

[DaTT]

Does your car run cool? Or does it get up to temp?

Thermostat or Heater core?

 

[Sixguns]

Up to temp

 

[tortillasoup]

if you have the original radiator cap, change it. also, see if the car fully warms up to operating temp with the temp knobs set to cold with fan blowing slowly, a/c off while parked. If it doesn't, drive the vehicle (yes it will be cold) and see if the temps warm up. There is a possibility there is still air in the system or that you have a stuck open thermostat (failed).

 

[local]

Diverter possibly failed. Meaning it is stuck somewhere between hot and cold. Check vacuum lines going into the firewall near the AC unit assuming this car still uses vacuum to move the diverter.

 

[Sixguns]

Vacuum lines where my guess just no idea where or how to locate them

 

[Zivic]

my guess is the heater core is clogged. flushing the the system as a whole can help, but disconnect right off the heater core and flush it directly

 

[Sixguns]

That makes sense zivic. I noticed the only time I get any real heat is when I have my air being circulated through my car. Not pulling air from outside.

 

[Blain]

Your blend door actuator (air mix motor), is electrical.

 

[mrblotto]

my guess is the heater core is clogged. flushing the the system as a whole can help, but disconnect right off the heater core and flush it directly

This

Our old Jeep's (2001?) heat stopped working. Turned out the radiator (thus water jacket and heater core) were plugged with so much sludge we ended up getting a new radiator.

To clean out the heater core, the mechanic disconnected both the inflow and outflow hoses on the heater core. Then he hooked basically what looked like a pressurized water gun to the outflow, and I just held an empty gallon jug on the inflow. Some pretty nasty stuff came out of there lol. Heat worked fantastic after that

 

[Raizinman]

An 03 Altima. That is 13 years old. How much service did you have done in the last 13 years on the cooling system?

Has your vehicle been to the dealer for:
2003 Nissan Altima Engine And Engine Cooling Recall 03V084000

When you bled the system, did you use the Nissan special radiator fill tool that puts about 25 inches of vacuum into your cooling system to pull the air out while filling? If so, did you make sure you filled the system while the heater control was ON, Ignition was ON with the engine OFF? I tend to doubt this being that you said you have limited tools.

I can tell you from experience that trying to bleed this particular system without this special tool is next to impossible which is why Nissan has this special tool. You can do a search of the Internet to find it or go here. http://boredmder.com/FSMs/Nissan/Altima/2003/MA.pdf Go to Page MA-16 which gives the bleeding procedure for your car.

At this point, I would strongly suggest that you take your vehicle to a Nissan dealer to check for recalls and have them bleed your system. If you continue to drive your car with an air pocket in the engine you could do serious damage to the engine (depending where the air pocket is located).