My 2008 Prius heater has always baked me out of the car in 10 minutes if set on high. Now it still heats, but does not bring the temperature up like before. After 15-20 minutes, although the car is warm, it is not hot where I need to turn it off or down like I have had to previously. This started this week. Otherwise, no issues with car. Cabin air filter was replaced last week, but I have checked it and it is fine. At present the situation is ok as there is heat and it is not extremely cold yet, but is it getting ready to totally fail? Thanks for any input !!!
Your anti-freeze may be low (so it isn't circulating well) or the thermostat is stuck (so it is constantly circulating). Either one will prevent the heater core from pumping out lots of heat. In both cases, an aftermarket device is the easiest way to confirm a coolant related problem. ($10 on Amazon for a reader and a free app download.) The temperature will help tell us what's going on.
Thanks, not sure what type of reader you are referring to, but I checked the coolant and is is full. It is protected to 40 below. Took a long trip yesterday and had no issues with heater except is not as hot as previously. Has about 140,000 miles currently.
Could be the coolant thermostat going. It'd be nice if the Prius had a coolant temp gauge, most any econobox car used to have it. You could monitor engine coolant temps with Scangauge or maybe other? If you have a thermostat failing in a manner that it's opening too soon, and/or not sealing properly when closed, you'll tend to be running too cold, especially with freeway driving.
