No heat through climate control system when vehicle is idling.
What is your question?
Whenever I am at a stop light or parked, and the engine revs go below 1500RPM, the heating system seems to "turn off" and I only get cold air. If I start to drive or rev the motor up, the system seems to switch over to heat. No codes are being triggered but on occasion, if the car is left idling, it will send an "Increased Emissions" warning on the Information screen and "MAP Thermostat Sensor - Mechanism" code will come up on my scanner.
There is an noticeable change airflow sound within the system when the motor revs climb from idle to higher revs. Almost sounds like the fan speeds up and vent doors open/close to redirect airflow goes through the heater core.
What are the possible issues and fixes?
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I don't know for sure, and diagnostic testing is definitely required, but I'm wondering if the engine is not getting fully to operating temperature all the time, and your climate control system doesn't blow enough warm air as a result.
It's always important to fix what you know to be wrong regardless, so definitely approach your diagnostic trouble code and see where that leads.
I have replaced the MAP thermostat last year because of a similar issue/code.
I also replaced the auxiliary coolant pump and coolant diverter valve on the heater flow circuit, as well.
I am going to change the coolant temp sensor next to see if that is the issue.
An online search of my symptoms did bring up the possibility of a malfunctioning MAP thermostat...yet again. My worry is that it is an issue with wiring/voltage signal to components that is creating the issue. not sure how I can test for that as I do not know the factory voltage parameters for the map thermostat, diverter valve or pump.
I'd like to suggest that you could create more problems replacing components that are working properly. Testing must be performed. You'll spend far more replacing unneeded parts rather than having the system tested by an experienced technician with the proper diagnostic tools on hand.
I have replaced the MAP thermostat last year because of a similar issue/code. I also replaced the auxiliary coolant pump and coolant diverter valve on the heater flow circuit, as well. I am going to change the coolant temp sensor next to see if that is the issue. An online search of my symptoms did bring up the possibility of a malfunctioning MAP thermostat...yet again. My worry is that it is an issue with wiring/voltage signal to components that is creating the issue. not sure how I can test for that as I do not know the factory voltage parameters for the map thermostat, diverter valve or pump.
I'd like to suggest that you could create more problems replacing components that are working properly. Testing must be performed. You'll spend far more replacing unneeded parts rather than having the system tested by an experienced technician with the proper diagnostic tools on hand.