Hey all,

Anybody know how straight (and size/restrictions) the air path is from the outside intake to the interior of the heater box?

I had a notion to use a duct cleaning contractor's remote camera to see inside the box and confirm whether the heater core was plugged before going through the pain of removal. This baby has no heat to speak of yet both lines are hot hot.

With any luck they might even be able to clean it. Do you think this is possible or am I dreaming.

Cheers,

Taz

 

The air coming into the truck first passes through the evaporator core so that is what would be plugged with contamination from the outside. If you have good air flow coming out the ducts then outside contamination is out of the question.
The heater core is likely plugged internally and needs a back flush, if you have not changed your antifreeze in a while this is the opportunity to flush the whole system.

 

Thanks Bus,

Not an issue. This system has been flushed to death with an Evanscool conversion and a 53 block replacement. I have good flow, just no heat transfer.

True, the airflow could be better. Tell me more about the inflow path. Are you saying the evaporator occupies the entire path?

Cheers,

Taz

 

ALL air whether in normal or recirc (MAX) mode first passes through the evaporator. Have you tried disconnecting the heater core and just flushing that? Use hot tap water and turn on the fan you should get hot air blowing. Just a thought the earlier trucks used a boden cable driven blend door and the later ones a RVDT. My truck (2001) has the (electric) RVDT and I believe there is a locator on the bottom of the blend door arm to make sure it's in the correct posn. If yours is the boden cable type the cable sometimes jumps out of the locator at either the sw end or the plenum end. The boden cable type are stiffer than the RVDT and if it's very free the cable has probably come off one end. They hardly ever break. Either way if there IS heat passing through the core and air is blowing through it and you don't have heat in the cab it must be a blend door problem. Even if the Air Con was running the heat should over power it so long as the blend door is all the way to the heat posn.

 

Im having the same problem with mine. Flushed the core not long ago along with the rest of the cooling system. I took the blend door actuator motor off to make sure it worked right- it does. Then tried to turn the door with a wrench and it wont budge. I figure the dealer left something in it as they fixed the AC before I bought the truck and the heat worked while i was test driving it. Is fixin this door real hard after you get the box out.