It seems to take along time for the fan to blow air

Location is behind right side of dash, on HVAC housing. A/C HEATER CONTROL PANEL REMOVAL/INSTALLATION: Disconnect the battery negative cable(s). Reach under the instrument panel on the driver's side near the transmission tunnel and unplug the heater-A/C control to housing vacuum harness connector. Disengage the retainer on the heater-A/C control half of the vacuum harness from the hole in the center of the distribution duct. Remove the cluster bezel from the instrument panel. Remove the screws that secure the control panel to the instrument panel. Pull out the assembly far enough to access the connections at the back of the control. Unplug the wiring. Disconnect the cable, if fitted. If a vacuum unit is fitted, remove the two stamped nuts that secure the vacuum harness connector and unplug the connector. Installation is the reverse of removal.

What do you mean of operation on outside cold air? Do you have an issue of the vehicle's engine heating or cooling properly?

Hello, I'm Danny.

It sounds like you might be having an issue with a defective, failing, or otherwise faulty blower motor resistor. This could be causing your blower motor to not perform properly. I've attached picture steps below for blower motor resistor replacement on your truck including its location. Hope this helps and thanks for using 2CarPros.