Cold incoming air with warm air

it's dead, jim. time for a troubleshoot and repair. These toyotas are notorious for climate control problems. Either your control panel is broken, or the electronic air blend motor is broken, or some plastic in between.

P0540 - Intake Air Heater Feedback Circuit
P0540 Description
The Engine Control Module [ECM] uses an Intake Air Heater (IAH) to warm the incoming air for proper cylinder combustion. The ECM grounds the control coil of the IAH relay to energize the heater during cold operation.

Sounds like your heater blend doors aren't adjusting from cold to heat. If you google "blend doors" you can read about them. They are usually pretty hard to get to, the dash needs to come out. Hope this helps! Jonathan Lavezzo www.lavezzoconstruction.com

needs the water system back flushing out, heater being cold is its blocked up some time a few back flushes and forward flushes with a hose pipe should free up the dirt inside, same with the engine and radiator. there are meany videos on you tube to help you understand how to back flush you engie. but do the radiator and engine and heater separate so the muck does not go back into the engine.

No ,there is not another valve . One low side service port an one high side service port . An only one A/C compressor . Under the hood in the engine compartment there are A/C lines going into the firewall . These go to the front Evaparator unit . With the vehicle running an A/C on do this line's (pipes) get cold ? If yes , your problem is probably the temp. actuator . Control's how hot or cold the air coming from the vent's get . If stuck half way , hot an cold air combine to make warm air . Replacing some of these actuators can require the dash to be removed . Your best bet ,take it to a qualified repair shop .

This sounds like your automatic climate control is starting to malfunction. Check to make sure your coolant is full, and temp is not fluctuating, and when your vehicle is warmed up, try using the low setting and feel for air temp. Is it warmer than if you turn it up? When at idle the vehicle is not producing heat the same as if you are driving, putting load on your engine and more air/fuel combustion means more heat, which is why you can feel heat while driving. Ideally you should feel heat as soon as the engine is warming up, getting hotter as it reaches peak temp of 190-210 degrees. You can try to make sure your water control valve is not blocked, and all electrical connections are secure. This will be located close to your firewall and connected to the coolant tubes that run into your firewall to your heater-core. Also use recirc (setting)to try to summon as much heat as possible, however ultimately, you may need to take you vehicle in for service. If it only warms when driving defrost will be an issue. Good luck.

system needs serviced possible low on ac fluid.

Since warm air eventually comes out when the vehicle is in motion, you may have an air mix door that is stuck in fresh or is somehow blocking warm air from the heater core.

To see if the air mix control motor is bad, you need to retrieve your Diagnostic trouble codes (DTC's) from the heater control panel. To run the diagnostic function, do the following:
1. Turn the ignition switch ON (II).
2. Turn the fan switch OFF.
3. Press the recirc control button to select Recirc (recirc light on.)
4. Press and hold the recirc button to select Fresh (recirc light off) and continue to hold the button down until the recirc light comes on for two seconds and then goes off.
5. If the system is okay, the recirc light stays off.
6. If there is a problem, the recirc light blinks the DTC to indicate the trouble. One blink=a problem in the air mix control motor circuit. Two blinks=problem in the mode control motor circuit
Three blinks=problem in evaporator temp sensor circuit.
7. Turn the ignition switch off to cancel the self diagnosis function. Run the diagnostic again after repairs are complete.

Note: the air mix control motor has a rod which connects to a plastic link. The link controls the mix doors and also connects to the heater control water valve via a cable. The air mix motor may check okay, but if the link is broken then you will still have problems. the motor is on the bottom of the heater unit in the front passenger's foot well.

tempareture control knob is need to replace

Its just a vent damper plate not operating, it's like a gate which controls the flow of air,,usually they are operated by vacuum, or cables.
Service center time, unless you are handy with your own repairs.