I replaced both my heater core and evaportor.This is a weird problem....The AC works perfect and cycles the way it should.When I switch it to heat,the air is just warm and the AC still cycles but alot slower.If I disconnect the AC,the air output is hotter.I notice also that on the heat setting,the two AC pipes are ice cold...Is this what they call evaportor freeze up?It seems the AC is still cooling while the heat is on...

 

The HVAC systems works like this.... Air is either drawn in from outside or from inside the cab during "Recirc", The fan motor pushes the air through the evaporator core first, regardless of which mode is selected. From here the air is "blended" (by the position of the blend door) by allowing some air to pass through the heater core and some to bypass it. From here the air is ported to the various outlets depending on which mode is selected. The compressor should run in the AC positions and also the defrost position on just about every vehicle made. HOWEVER Dodge did I believe have the compressor run in all positions except OFF on some years. My 2001 is all AC and def only.

The air that passes through the heater core should be very hot and more than capable of overpowering the cool or cold air. Think about winter when the air entering the vehicle is -40 and the heater is able to warm it up nicely. The air coming through the evaporator core cannot be below 32 deg or zero as the core would freeze.

So I say that you either have the engine cooling system not full, the heater hoses hooked up backwards (they should cross) or the heater core is air locked or partially plugged. If your truck was designed to run in all positions except off you could easily wire a toggle switch into the hi and lo pressure circuit to keep the compressor off until you want it to run.

 

I did the crossover on the heater lines....

 

I just thought of a couple of other things... Nearly all the second gen trucks have an electric motor that moves the blend door but on your 1995 truck the blend door may be cable operated, some of the early ones were. It may be possible that the blend door is not fully traveling. This is fairly easy to see. The bottom of the blend door is on the passenger side close to the hump. If it's cable driven you can move the control and see just what is happening. The cable would sometimes bend and mostly all you would be doing is bending the cable with just a little door movement.
The other thing is the engine getting up to temp, maybe the thermostat is not a 190deg? One other thing, some heater cores come with black rubber plugs if one was missed being removed it could have been driven into the core with the pressure partially blocking it. Seen that on occasion.