'10 Dodge Ram heater not hot.

Sounds like the heater core. Do you smell antifreeze inside the truck or is the floor wet on the front passenger side?

No antifreeze smell and no wet floor on passenger side.

The thermostat is either open or is missing inside the thermostat housing on the engine

There are several possible reasons. First confirm your engine is to operating temperature (170-190 F) by placing your hand or using an infrared thermometer on the upper radiator hose. If using your hand be careful and very momentarily and very lightly touch the upper radiator hose it should feel very hot and uncomfortable. Using an infrared thermometer it should be about 150-190 degrees Fahrenheit (preferred safer method). Then locate two 5/8 to 3/4 inch hoses side-by-side going into your passenger side firewall. These hoses carry hot engine coolant into and back out of your heater core (tiny radiator in your cab). Next touch them (not really recommended...) or using your infrared thermometer make sure they are at the same temperature as your upper radiator hose. If yes, then your heater core is in good working condition and is moving hot engine coolant through it. If one heater core hose is hotter than the other one then your heater core is plugged up and not moving hot engine coolant through it - time to replace it. If both are basically the same temperature then remove your glove box and locate the actuator to left side of the glove box cavity. You will see a white tab behind the actuator. With vehicle running and HVAC system on, rotate temperature control knob from hot to cold and back from cold to hot. You should see the white tab cycle from 6 o'clock (cold) to about 3 o'clock (hot). If the the tab is not moving then remove the blend door actuator and hook it up to your battery (use blue/red wire for negative). If the actuator is in good working condition you will see the actuator's output shaft continue to rotate (slowly). If actuator is rotating while hooked to 12 volts then confirm your temperature blend door is functional by moving the white tab from cold to hot and back from hot to cold. Inspect tab and actuator output shaft for worn splines as well. If all checks out then your most likely problem is your AC or HVAC control module. At this time you will need to refer to a service manual or take it to a qualified repair shop.

The heater will only get as hot as the settings will allow which is 85 degrees it won't get as warm as the engine which in turn suck's .It can not be adjusted high enough .

I have the same thing

I have the same thing , so I even flushed out the heater core and changed the water pump and thermostat and took off the dash to check the actuators under radio and changed actuator behind glove box, checked the blend doors all in working condition and all hoses under the hood are hot. Still blowing cold air. But when I move the heater control modular to hot and back to cold the white actuator moves up and down so still don’t know the problem

If you have confirmed you are passing hot engine coolant through your heater core and your blower motor fan is operational then your problem will be related to the vents doors inside your air ducting. There is more than one vent door inside your air ducting - there are vent doors to direct the air to the windshield, face, or feet. There is also a vent door to direct cold air or hot air into the passenger compartment - when you command cold air - air is not blown across the heater core. When you command (dial in) hot air a vent door is actuated to make sure blower motor air is passed over/through your heater core. I would say your hot/cold vent door is not operating correctly. Here are all the things that could go wrong - the actuating arm to the door is broken, the vent door is stuck, the acutating step motor has failed, the electronic control unit has failed - this is basically a small computer board attached to all the HVAC system control knobs. Linkage has detached, etc. FYI - do not buy after market (NAPA, Autozone, RockAuto) actuator stepper motors - they DO NOT work with the vehicle's HVAC computer correctly - always buy these stepper motors from the dealer - they are usually the same price.

So would that be the actuator behind the glove compartment? Because I replaced that and the white piece is moving up for heat and when I move the control to cold, the white piece moves down

Also is it pretty easy to get to the hot/cold door to check it if it operational ? Thank you for your help!!!