Yes. Read post #72 in this thread:
This is an outstanding thread, thanks for all of the info! We're all on the same team here, and we all want very much to enjoy our expensive trucks. Even if we have to do a little tweak here and there. Welcome aboard!
5thgenrams.com
Blend door issue: Behind your dash is an HVAC box (heat/ventilation/air conditioning). In this box is a blower motor (fan) - you control the speed of this fan through your heat/AC controls - from 0 to 7. This fan either sucks air in from the outside (in normal mode - from the cowl vents at the base of the windshield), or from the floor of the cab (in recirculation mode). This function is controlled by the "recirc door" - basically a flap that closes off either of the above passages, so the fan is only sucking from one source.
Now, the blower (fan) pushes the air it just sucked in across the A/C evaporator coil. When the A/C is on, this coil gets to be about 36-38 degrees, thanks to the refrigerant (we won't get in tow HOW this works - for now, it's enough to know that the coil is cold). The air blowing across this coil gives up most of it's heat to the coil, warming the refrigerant in it, and therefore becoming cold itself (as a by-product of cooling the air, it can't hold as much moisture, so the moisture condenses on the coil and drips off - like a glass of iced tea will "sweat" in the summertime - that's where the "A/C condensate" comes from, and why your truck drips water when the A/C is running). When the A/C is off, this coil does nothing, and the air just passes over it with nothing happening.
Next in line is the aforementioned "blend door". Again, it's a flapper, like the recirc. door we talked about before, but unlike the recirc. door, the blend door has many positions. It's job is to direct none, some, or all of the incoming, possibly cooled, air over the heater core to get warmed up. Unlike the A/C evaporator, which is only cold when the A/C compressor is running, the heater core is hot virtually all the time. The engine coolant is constantly cycled through the heater core (which is itself nothing more than a tiny radiator). Whatever your coolant temperature gauge reads, that's the temperature of the heater core.
When your HVAC controls are on "full hot", all of the air being pushed through the A/C evaporator coil will then be directed through the heater core. When your HVAC controls are on "full cold", NONE of the air should go across the heater core - it should all bypass the heater core, so it stays cold. And when your settings are somewhere in the middle, some of the air goes through the heater core, and some bypasses it. We're "blending" the cold air and the hot air to arrive at a desired temperature.
What's happening, is even when you have the system at "full cold", some of the air is still going across the heater core (it shouldn't, but it is), resulting in warmer-than-desired air temps. We know this, because when the supply hose to the heater core is clamped off, resulting in a cool heater core, the observed temperatures at the vents become, on average, 10 degrees cooler.
Hope that helps some.