Fix the temperature indicator for cooling system

Which of these two systems does your truck have?

Electronic Automatic Temperature Control (EATC) System
Or
Electronic Manual Temperature Control (EMTC) System


Electronic Manual Temperature Control (EMTC) System
The electronic manual temperature control (EMTC) system heats or cools the vehicle depending on the EMTC control panel selection.

• The EMTC control panel selections determine heating or cooling, air distribution and enables blower motor operation.
• The temperature control setting determines the air temperature.
• The blower motor switch varies the blower motor speed.
• During A/C operation the system also reduces the relative humidity of the air.

The EMTC system operation is determined by the settings on the climate control module. The EMTC system is composed of the EMTC module, blower motor resistor, mode door actuator, air inlet door actuator and temperature blend door actuator to control the various functions.
The blower motor switch:

• sets the blower motor speed.
• directs the blower motor path to ground through the blower motor resistor to allow blower motor operation in LO, MED LO and MED HI.
• directs the blower motor path directly to ground, bypassing the blower motor resistor, to allow blower motor operation in HI.

The A/C request button:

• can command the A/C compressor ON when the function selector switch is in PANEL, FLOOR/PANEL, FLOOR/DEFROST and FLOOR when the A/C request switch is pressed. Indicator illuminates when A/C request switch is toggled ON.
• is inoperative in MAX A/C, OFF and DEFROST.
• indicator illuminates when the function selector switch is in MAX A/C and cannot be toggled.
• indicator does not illuminate in OFF and cannot be toggled.
• indicator does not illuminate in DEFROST but can be toggled ON or OFF. The A/C compressor will operate regardless of indicator status if the outside air temperature is above 6°C (43°F).
• is serviced only with the EMTC module.

The function selector:

• selects airflow direction.
• is serviced only with the EMTC module.

The temperature selector:

• selects full warm and full cool as well as blended outlet temperatures.

The air recirculation button:

• selects either recirculated or outside air source.
• recirculates air in any mode except DEFROST, if requested.
• is disabled in MAX A/C or OFF mode where recirculated air only is used.
• is disabled in DEFROST mode where outside air only is used.
• is serviced only with the EMTC module.

The EMTC module also includes:

• a heated mirrior button. Refer to Section 501-09 .
• heated seat controls. Refer to Section 501-10 .

DISCONNECT THE BATTERY

P1299 - Cylinder Head Over Temperature Protection Active Indicates an engine overheat condition was detected by the cylinder head temperature (CHT) sensor. An FMEM Strategy called Fail-safe Cooling was activated to cool the engine.

• Engine cooling system concerns
• Low engine coolant level
• Base engine concerns

Refer to Section 1, Electronic Engine Control (EC) System , for more information on Fail-safe Cooling Strategy and cylinder head temperature sensor.

The engine is swelling because of the over heating. Stop using it !!!!!!!!! Gotta fix cooling system lest you seize the engine.

check the lower (suction) radiator hose that it cannot collapse, they usually have a metal coil inside to prevent this. If you left this out when installing the water pump it could be the cause..What temperature is the gauge reading? You could have been running too cool before and now that the new thermostat is in its up to normal temperature.

Low airflow through the heater is a separate issue and can be caused by leaves in the ductwork, a blend door not opening/closing fully, clogged heater core (are you a smoker?) Good luck.

Edit: I had another thought on this.. the cooling system needs bled carefully, air in the system can cause symptoms like you describe, look for a bleeder screw on top of the engine somewhere and make sure to let the air out of the system.

This is an indication of air or gas bubbles in the cooling system, it can be that the system is low on coolant due to a leak (have a cooling system pressure test performed) or that you have a leaking engine cylinder head gasket. I would also replace the thermostat just to rule it out as a cause, it could be sticking and causing the rapid swings in engine temperature.

2005 Instrument cluster layout

1. Speedometer
2. Brake warning light
3. Turn signal indicator light
4. High beam indicator light
5. Malfunction Indicator Light (MIL)
6. Airbag warning light
7. Anti-Lock brake warning light
8. Tachometer
9. Security alarm indicator light
10. Oil pressure warning light
11. Electronic Stability Program (ESP)/
Traction Control System (TCS) indicator light
12. Tire Pressure Monitor warning light (base)

13. Temperature gauge
14. Electronic Vehicle Information Display
15. Tow/Haul indicator light
16. 4WD Low mode indicator light
17. Seat belt reminder light
18. Cruise control indicator light
19. Odometer/Trip Odometer
20. Transmission gear indicator
21. Fuel gauge
22. Electronic Throttle warning light (5.7 Hemi)
23. Front fog light indicator light
24. Voltage warning light

Water Temperature Indicator Sender Unit
The water temperature indicator sender unit is installed on the engine into an engine coolant passage. The water temperature indicator sender unit reacts to the engine coolant temperature. Its resistance decreases as the engine coolant temperature increases.

Water Temperature Indicator Sender Unit Removal
CAUTION: Do not mix Standard (green) Coolant with Extended Life Coolant (orange). If mixing occurs, drain engine cooling system and refill with originally equipped coolant type. If this contamination occurs the service change interval on Extended Life Coolant will be reduced from 6 years/150,000 miles to 3 years/30,000 miles.

1. Partially drain engine cooling system as described.
   

1. Disconnect engine control sensor wiring (12A581) from water temperature indicator sender unit (10884) .
   

1. Remove water temperature indicator sender unit.
   

You could possibly have air in your cooling system. If the dash gauge temperature sensor does not have coolant flowing past it, it will give a false temperature reading while your engine is actually overheating. If you recently drained and refilled your cooling system, you might need to bleed the air out of that system. If you didn't drain it recently, you might have a leak that's letting out coolant and letting in air.

I will assume that you are speaking of the thermostat when you say "valve".

In that case removing the thermostat can cause boil over in long run conditions in elevated temperatures as it has no way to stop or divert the coolant flow to cool the coolant an reintroduce it back to the cooling system. Also unless you plan to run the car longer than 45 minutes before you drive; your windshield defogger/defroster will not work enough to clear the window on rainy days.

50% to 60% as you describe; on the temp indicator I would consider normal operation.

~ Hope this was of help and answered your questions