Poor circulation probably due to a restricted (plugged up) heater core.
When a vehicle is idling, the engine may not produce enough heat to warm the coolant effectively, leading to cold air from the heater. In contrast, while driving, the engine works harder and generates more heat, allowing the heater to blow warm air. The engine temperature can rise while idling due to reduced airflow through the radiator and less coolant circulation, while driving increases airflow and coolant flow, helping to cool the engine.
Low coolant, failed thermostat, partially plugged heater core...............
Well it should blow cold while driving and stopped. You probably need to get your AC recharged. Hope I helped!!
you need to replace your heater core
I'd check the coolant level first, then the thermostat.
Possibly defective thermostat. It sounds like it is opening up a bit with increased pressure caused by higher engine revs - when idling, the pressure decreases and the thermostat valve closes. Just a thought, anyway.
That's a toughy... Water pump maybe(?)If not, be sure to see "Related Questions" below for more diagnosing/trouble-shooting/fixing ideas and information.
Could be a number of reasons for this condition. I would check the coolant level. A low coolant level could cause your heater to blow cold air when the engine is warm. Is the engine warm? If the engine is fluctuating temp it could be a faulty thermostat. Hope this helps.
A car blowing cold air only while driving usually means: Low coolant level – not enough heat at idle Air trapped in system – blocks heater flow Weak/bad water pump – works better at higher RPM Partially clogged heater core – needs more flow to heat When you drive, coolant moves faster, so you finally get heat.
This is often caused by air being trapped in the cooling system. Get a qualified mechanic to drain, flush and refill the radiator/cooling system.
Yuo have a bad aux water pump about $150 at the dealer :) Danny K
It is either your water pump or your thermostat