Heater Performance Mode Active?

jashaw · February 23, 2023

On 1/26/2022 at 7:20 PM, JCoutts61 said:

I also have the 2.7T and asked at the dealership about this. I was told it activates the defrost mode when using the remote start in extremely cold weather, to assist in not having the windshield fog up when entering the vehicle.

My 2.7 has the defrost on full blast using remote starts regardless of where my fan knob is. I think it's normal for the defroster to be on below about 45-50 degrees F. Fan speed seems to vary with outdoor temps. Ive had it be almost off when the cab temp is about 65 in spring/fall.

The A/C will kick on in if cab temp is above a certain number. Dont know what that is though.

newdude · February 24, 2023

Normal operation on the 2.7. A function of the Active Thermal Management. 2.7 uses an electric water pump and the ATM has 7 modes of operation. See below:

Mode 1 (LOW FLOW):

If the engine is started cold, the system will go to low flow mode, which means the electric water pump runs just enough for the sensors to provide reliable information on the state of the system. The engine heats, the heat stays around the combustion chamber and is not taken away by coolant flow. low flow mode is the fastest method for engine warm up.

Mode 2 (ENGINE WARM UP WITH CABIN HEATING ONLY):

When the driver requests passenger compartment heat or windshield defrosting, the electric water pump will control flow to maximize coolant heat transfer from engine to passenger compartment. This heater circuit is fed by a combination of warmed coolant from the cylinder head, integrated manifold and turbocharger cooler. The engine coolant flow control valve is at an all-closed position at this time. The warmed coolant goes directly to the passenger compartment heater core. Heater core flow returns to the electric water pump.

Mode 3 (ENGINE WARM UP WITH CABIN HEATING AND RADIATOR BYPASS):

The cylinder head, integrated manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. During Mode 2, coolant does not flow through the cylinder head. As combustion chamber temperatures get hotter, it is necessary to flow coolant through the cylinder head without losing heat to the radiator or engine/transmission oil heat exchangers. The Block Rotary Coolant Valve will allow flow through the cylinder head by opening the radiator bypass loop, which returns coolant directly to the electric water pump.

Mode 4 (ENGINE WARM UP WITH CABIN HEATING, RADIATOR BYPASS AND OIL HEATING):

The cylinder head, integrated manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. Once the optimal combustion chamber temperature has been reached, warmed coolant can be used to quickly raise the engine and transmission to their optimal temperatures. The engine coolant flow control valve will still allow flow through the cylinder head with the open radiator bypass loop but will now also allow coolant flow to the engine/transmission oil heat exchangers. Coolant flow from the bypass and heat exchangers returns to the electric water pump.

Mode 5 (ENGINE-DEMAND COOLING WITH CABIN HEATING AND OIL HEATING):

The cylinder head, integrated manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. At this point, the combustion chamber temperature has reached its optimal temperature and the engine needs to dissipate heat through the radiator. Based on engine temperature, the engine coolant flow control valve will split the flow between the radiator and bypass in a ratio necessary to maintain optimal engine temperatures. Additionally, coolant flow will continue to flow to the engine/transmission oil heat exchangers. Engine oil and transmission oil can take significantly longer time to reach optimal temperatures after the engine is already warmed. Coolant flow from the radiator, bypass, and heat exchangers returns to the electric water pump.

Mode 6 (ENGINE-DEMAND COOLING WITH CABIN HEATING AND OIL COOLING):

The cylinder head, integrated manifold and turbocharger cooler passages are still flowing and providing warmed coolant directly to the passenger compartment heater core, if requested. On rides in extreme hot driving conditions, the engine and transmission become extremely hot and their oils need to be cooled. The engine coolant flow control valve will continue to split the flow between the radiator and bypass in a ratio necessary to maintain optimal engine temperatures and will now allow colder coolant directly from the electric water pump to flow to the engine/transmission oil heat exchangers. Coolant flow from the radiator, bypass, and heat exchangers returns to the electric water pump.

Mode 7 (AFTER RUN COOLING):

The after run mode is after key off and is needed only after extreme hot conditions with high engine, oil and coolant temperatures. For after run mode, the same valve positions are used as in Mode 6, but the electric water pump is run at a lower speed to continue cooling.

Modes 3 and 4 my guess are what trigger that "Heater Performance Mode Active" message on the dash as the cooling system is attempting to rapid heat the cab if possible. One other thing I've noticed is that the 2.7 will high idle at 1500rpm during these very low ambient temp cold starts to aid in the heating.