2010 Prius 2 85k Miles Cold weather hit SoCal, hey great!, my heater isn't working. Takes a full 1/2 hour to even get maybe room temperature. It use to work just fine... I've been driving to work like thsi for a week hoping it would return. Today it was sunny and warm. I see ow that the AC light no longer comes on either, and neither does the cold air. If it's on AUTO it just defers to outside air no matter what. So...I've checked all the fuses for AC or Heat under the dash and the hood, all are good. I replaced the cabin filter and did a general cleaning under the dash begind the glove compartment. I mad sure the fan is blowing. Ready to hold my breath and go to the dealer...ouch. Anything obviious I should know?
Well I just fiddled around with it again, ran the temp adjustment all the way down to LOW and the AC light did come on. It does appear the A/C is still working and I can turn the AC button on and off. So I put it all the way on High to test the heater. I drove around for a while and the air coming out is tepid at best. Fan and vents are all working as they should, the heat is just not very warm.
Do you mean how is my battery? I'm pretty sure it's the original...but how does that affect the heat?
The heater just works off the internal heat of the engine. So if it's blowing, it should be transferring heat. Have you tried raising the temp. with the button to the left? (up/down) Just asking. It works by circulating fluid threw the engine. If the engines hot, heat reaches easily to passenger compartment with the help of the blower I wouldn't go to the dealer just yet. Think you'll get it. A.C. is a bit more complicated but heat is, if the blower's working, should be an easy fix.
Just wondering Bisco. Wouldn't the car be over heating if it was a bad thermostat? Or is there a second, besides the ICE one?
How’s the engine coolant level? Have you tried to feel the reservoir or hoses after the Prius is run for a bit?
if it were stuck closed, it would over heat. if it is stuck open, it won't warm up. i think the failsafe is open, so it won't overheat. also, the coolant valve could be bad.
Any trouble codes from the heater? (Hold down auto+recirc while putting the car ON; look for two-digit codes where the set temperature usually shows.) There might not be any, but there's no point in not checking when it's so easy. -Chap
Checked the coolant level, it's spot on. If everything in this car is sam as any other, first thing I'd think too is a thermostat. But I don't know where it is Never had one problem with this car. I run it in Power mode 90% of the time. It seems to me the motor isn't getting hot enough, thus = thermostat... "Hold down auto+recirc while putting the car ON; look for two-digit codes where the set temperature usually shows" I'll try that!
No codes. I did the auto+recirc while putting the car ON dealie and it just showed "00". On the way to work I put the temp on HI and nothing. 30 minutes later and again the heat was just barely warm if at all, just warmer than the 46 degree outside air. So...thermostat?
I've had a thermostat failing, in such a manner that the engine was cooling too well. It's supposed to stay closed until the engine's warmed, but if the gasket's frayed, and/or the mechanism is allowing it to open too soon (and close too late), and you're doing something like freeway driving, the coolant will be flowing freely to the radiator, and cooling too efficiently. Back in the day with the 1990 Accord in question, there was this quaint old-school gauge in the dash that showed your coolant temp. (If this sounds like a rant, it's because it is.) Anyway, commuting to work up the valley, I'd notice, as I was coming off the freeway, the coolant gauge needle was right down at the cold end, not good.
You can check the coolant temperature by grabbing some hoses after the engine has warmed up some, or by using any OBD-II reader to watch the coolant temperature. If the coolant gets hot, there's really only one other plausible culprit. The heater's air discharge temperature is controlled by an "air mix" door that moves to control how much of the air goes through the heater core, picking up the heat from the coolant, and how much of the air goes around it. I would try to get a good view of the servo linkage that moves that door (up under the dash) to see if it moves, and covers its full range of motion. You should be able to see it move all the way to the cold end (directing all air around the core, not through it) if you just set the temperature to LO, and then if you change the setting to (anything several degrees higher than the surroundings), it should swing in the heating direction. -Chap
