Quote:
Originally Posted by California98Civic
On my Civic that air is not hot if I have the HVAC temp setting on the "cold" side. On the 6th Gen Civic, the temp selector cuts off the hot coolant from circulating into the heater core.
|
The air isn't noticeably hot as if it is being heated since I blocked off the underhood part of the HVAC air intake, but since it is outside air it is still hot and humid in the summer and therefore adding load to the AC system and forcing me to use it more.
My 7th gen Civic had a heater control valve also, but I removed it when I installed my oil cooler/warmer since I needed constant coolant flow. Last summer I bypassed the heater core, but I didn't notice any difference in air temp or AC performance so I didn't bother this summer.
It seems like heater control valves are becoming a thing of the past, lots of newer cars such as the 8th gen Civic and newer don't have heater control valves. I suppose the manufacturers decided that the extra cost wasn't worth it since very little/no air flows through the hot heater core when the heat isn't on anyways since the blend door blocks the airflow.
I have heard that the main point of the HCV is to extend the heater core's life by preventing the erosion caused by constant coolant flow when it isn't needed and to improve emissions by speeding up the engine's warmup by reducing the volume of coolant that needs to be heated when the heater isn't on, but I don't know how true that is.