When the fan is on low the heat is hot , when I turn it to high the temperature becomes cool.
Any thoughts?

 

Heater core is blocked to a trickle. Remove Heater core fittings under hood, and flush in reverse direction to try to get gunk out. You really don't want to replace core, the truck is built around it.

 

Check coolant level.
Flush heater core.
Replace t-stat.
Heater cores not that hard to replace, there is a cheater method.

 

Oops, I forgot about coolant low. If coolant is low, just steam in the heater core. But that could mean coolant leak or worse problems.

Thermostat could be stuck open, so low coolant temp to start with (no matter what dash gauge says).

As for easy heater core swap, let us hear more of this.

 

I've posted it before, you get to the heater core from under the dash, unbolt part of it from the firewall, pry it open, heater core falls out.

 

Hey Spike can you post a link? Sounds like a sticky candidate!

 

Agreed. We'll all have a bad heater core eventually.

 

Coolant levels are fine.
Temps on the ultra gauge are normal.
I will check the rest of the solutions next week.
Do you guys think its safe to drive?
I have other vehicles so I don't have to drive it,I just like driving it.

 

Google it, thats what I did.
There is also a write up in the Range Rover section, P-38 is the same thing as a DII.

 

Is there the under dash gurggle or water fall sound?
is there heat at the radiator in the front?

In the morning, make sure the coolant tank is filled to the fill line for COLD.