3rd Gen Tech: Colder AC in under 25
Diesel Bomber
Joined: Mar 2007
Posts: 3,910
Likes: 335
From: Capo Beach, CA
This should work on almost any vehicle to some degree.
On most vehicular air conditioning systems, all air goes through the air conditioning evaporator. From there, it can take two paths; one path leads straight to the vents, the other goes through the heater core. The amount that takes either path is determined by the "blend door" or "mix door". When the slider or **** is all the way in the "red" position, the blend door directs all of the air through the heater core; when it's in the "blue" position, the blend door directs all of the air around the heater core.
Even if the door directs all of the air around the heater core, the heater core is still hot and warms the air up a little bit through heat soak. Some vehicles (like 3rd gen Dodges apparently) have more problems with heat soak than others. Older vehicles (like 1st gen Dodges) tended to use valves that shut off the heater core automatically; I don't know why they went away from them.
A 15 degree decrease almost makes me think that these trucks are having problems with the blend door not closing all the way; that's a lot of heat soak, and a poorly designed air box if it has that much heat soak.
On most vehicular air conditioning systems, all air goes through the air conditioning evaporator. From there, it can take two paths; one path leads straight to the vents, the other goes through the heater core. The amount that takes either path is determined by the "blend door" or "mix door". When the slider or **** is all the way in the "red" position, the blend door directs all of the air through the heater core; when it's in the "blue" position, the blend door directs all of the air around the heater core.
Even if the door directs all of the air around the heater core, the heater core is still hot and warms the air up a little bit through heat soak. Some vehicles (like 3rd gen Dodges apparently) have more problems with heat soak than others. Older vehicles (like 1st gen Dodges) tended to use valves that shut off the heater core automatically; I don't know why they went away from them.
A 15 degree decrease almost makes me think that these trucks are having problems with the blend door not closing all the way; that's a lot of heat soak, and a poorly designed air box if it has that much heat soak.
Newbie
Joined: Apr 2009
Posts: 8
Likes: 0
From: Phoenix, AZ
Hey wildcat, nice post. Is anyone else worried about having the coolant dead-end at the valve. My last car was a blown Cobra and they have a known problem with trapping heated coolant at the back of the head. So much that they sell kits to route coolant from the back of the heads back in to circulation. I'm not sure if it would cause any problems but it sure makes me nervous to block off a coolant path, especially dealing with our summers in Phoenix. I've thought about adding more valves, a crossover or something to that effect. Heck, even a quick disconnect system may work. Your thoughts?
Last edited by 65StangBoy; Aug 1, 2009 at 02:11 AM.
Diesel Bomber
Joined: Aug 2007
Posts: 6,157
Likes: 371
From: TIKRIT, IRAQ
Hey wildcat, nice post. Is anyone else worried about having the coolant dead-end at the valve. My last car was a blown Cobra and they have a known problem with trapping heated coolant at the back of the head. So much that they sell kits to route coolant from the back of the heads back in to circulation. I'm not sure if it would cause any problems but it sure makes me nervous to block off a coolant path, especially dealing with our summers in Phoenix. I've thought about adding more valves, a crossover or something to that effect. Heck, even a quick disconnect system may work. Your thoughts?
Thread Starter
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Diesel Wrench
Joined: Dec 2008
Posts: 683
Likes: 80
From: Black Canyon City,AZ
65Stangboy, On the 2005 -2007, the heater core is a parallel path, so no worries. You also have the liquid to liquid tranny cooler off the back of the head... Might be like that on other years as well.
Newbie
Joined: Apr 2009
Posts: 8
Likes: 0
From: Phoenix, AZ
Good to know. You better believe I'm going to do this this week. My A/C is adequate, but I want to freeze. I read about this awhile ago, if I was smart I would have done this before it got stinking hot.
Diesel Enthusiast
Joined: May 2009
Posts: 110
Likes: 2
From: springfield illinois
Nice mod 
The only thing I would do is open that valve 2-3 times a month and let fresh coolant into the heater core. I would suspect letting that old coolant sit in the core for months would start to become corrosive and cause the core to fail come winter time. Like it used to do on the older cars.
The only thing I would do is open that valve 2-3 times a month and let fresh coolant into the heater core. I would suspect letting that old coolant sit in the core for months would start to become corrosive and cause the core to fail come winter time. Like it used to do on the older cars.
