DIY Home Improvement Forum banner

Heater core cages, have drain?

788 Views 4 Replies 3 Participants Last post by  Colbyt
Does anyone know if heater core cages, the box that contains the heater core have any drain?

I have a terrible stink in my AC system. I pulled the glove box and removed the resister switch expecting to find rampant mold in the evap core and box. There is none visible.

The truck was never left out overnight with the windows down. Intake screens are intact. I can not imagine how something got in there and died. Garage keep. Problem started this spring.

Before I foam the heater core and evap core with a cleaner I need to determine how the heater core part can be drained. The evap core will take care of itself.

1996 Nissan D21 Hardbody.
1 - 5 of 5 Posts
Yes, the heater core/evaporator box has a drain. Generally it's under the heater hoses or the A/C lines going into the firewall. If the smell is a dead animal, you will have to remove the box and clean it. I have found mice in the blower motor squirrel cage. If it's a musty smell, clean drain and there is a spray that you can introduce into the A/C that will get rid of the smell. Can't remember the name. A/C deodorizer? I have blown the drain with air and used a coat hanger to clean the drain. Don't go to far with coat hanger as you might poke a evaporator or heater core.:vs_cool:
  • Like
Reactions: 1
The heater core box and the evaporator coil box are 2 different boxes on a 96 Nissan and apparently a lot of other vehicles. My AC coil drain box is not stopped up.

I wish I could define the smell.
My AC coil drain box is not stopped up.

What is "stopped up"? Plugged?

You have mold build up on exchange radiator aka core, fins. This builds up if AC is not turned off about a minute before vehicle shut down, with blower still running, to remove moisture from fins. Especially in humid climate.

Foam it, there are several commercially available kits for that.
  • Like
Reactions: 1
Foam it, there are several commercially available kits for that.

The blower side of the coil is clean. The other side may be awful. No way to see it. I have the foam and intend to use it.

I can not go up the drain as the hose does 2 - 90's within a few inches and would never make the turn even if I could get to it.

I am trying to decide whether or not to hit the heater coil from the center vents, hence the questions. I suppose the air flow will dry it eventually if I don't flood it.
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.