Heater Blowing Cool Air
03-05-19, 12:40 PM
#1
Heater Blowing Cool Air
I hate to create another one of these threads, but I cannot figure out the reason behind my heater blowing cool air. I've located other threads, but they either aren't the same symptoms that I'm experiencing or the OP never posted a solution.
Moving on...my heater frequently blows cool air. It happens at idle, driving city speeds, and highway speeds. It will get a little warmer with higher RPMs, but not to the temp. it should. I have noticed that when it is set at "80" and above is when the warmer air tends to be more consistent, while "79" is typically when it blows noticeably cooler. This issue does not happen each and every time I put the heat on, but it does happen more often than not.
Moving on...my heater frequently blows cool air. It happens at idle, driving city speeds, and highway speeds. It will get a little warmer with higher RPMs, but not to the temp. it should. I have noticed that when it is set at "80" and above is when the warmer air tends to be more consistent, while "79" is typically when it blows noticeably cooler. This issue does not happen each and every time I put the heat on, but it does happen more often than not.
- I've checked the coolant level. A few weeks ago I was at the "min" tick mark, so I purchased Toyota/Lexus SLL coolant and topped it off...the coolant has remained at the "max" level since. That may have fixed it temporarily, but definitely not permanently.
- I've checked for leaks around the water pump and on the ground and have found nothing that leads me to believe I have a leak. I do not hear any grinding noises either.
- I've burped the system. Opened radiator cap and started the car. Let the car idle for about 10 minutes. Then turned on heat to HI and fan speed to max. Radiator fans kicked on and coolant level dropped a bit. I topped off the coolant level. I then carefully massaged the upper hose (coolant level rose while putting pressure on hose, but dropped once pressure was released)...little to no bubbles appeared. I repeated this for about another 10-15 minutes...still no bubbles.
Last edited by rizzy; 03-05-19 at 02:00 PM.
03-05-19, 09:26 PM
#2
Honestly that's probably not the best way to bleed coolant. You need an air tight seal, and just be liquid. Same function as the over flow tank. The cap hose is submerged in liquid. So that when the engine pulls in it's just refilling water to the engine.
So I recommend the funnel in the link. I've had mine for maybe 6 years now. It's probably one of my good items to do radiator work. Get the one with multiple vehicle attachments. So if needed be use it on other makes. You'd be surprised how much air is trapped in the coolant system.
Last if you go this route, and find no air trapped in your coolant. Then look into maybe the blend, or mix flaps not opening at the heater core. And yes on a normal day even in cold weather my heater is probably blowing extremely hot air at 75 deg, and above. In the summer once maybe the AC gets that mildew smell. After a drive I crank the heater to Max heat to try, and wipe out the bacteria.
So I recommend the funnel in the link. I've had mine for maybe 6 years now. It's probably one of my good items to do radiator work. Get the one with multiple vehicle attachments. So if needed be use it on other makes. You'd be surprised how much air is trapped in the coolant system.
Last if you go this route, and find no air trapped in your coolant. Then look into maybe the blend, or mix flaps not opening at the heater core. And yes on a normal day even in cold weather my heater is probably blowing extremely hot air at 75 deg, and above. In the summer once maybe the AC gets that mildew smell. After a drive I crank the heater to Max heat to try, and wipe out the bacteria.
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rizzy (03-06-19)
03-05-19, 10:58 PM
#3
You better check for head gasket leak. I have seen a few car at our shop having same problem and all turn out they have leak head gasket.
Failure radiator cap could also create the problem as well. If i were you, i would replace the radiator cap first, then check the pressure at the radiator cap (after the car parked for at least 2 hour) to see if you have any pressure or not. Let us know!!!
Failure radiator cap could also create the problem as well. If i were you, i would replace the radiator cap first, then check the pressure at the radiator cap (after the car parked for at least 2 hour) to see if you have any pressure or not. Let us know!!!
The following users liked this post:
rizzy (03-06-19)
03-06-19, 05:50 AM
#4
Honestly that's probably not the best way to bleed coolant. You need an air tight seal, and just be liquid. Same function as the over flow tank. The cap hose is submerged in liquid. So that when the engine pulls in it's just refilling water to the engine.
So I recommend the funnel in the link. I've had mine for maybe 6 years now. It's probably one of my good items to do radiator work. Get the one with multiple vehicle attachments. So if needed be use it on other makes. You'd be surprised how much air is trapped in the coolant system.
Last if you go this route, and find no air trapped in your coolant. Then look into maybe the blend, or mix flaps not opening at the heater core. And yes on a normal day even in cold weather my heater is probably blowing extremely hot air at 75 deg, and above. In the summer once maybe the AC gets that mildew smell. After a drive I crank the heater to Max heat to try, and wipe out the bacteria.
https://youtu.be/zUpXgAJ1gjU
So I recommend the funnel in the link. I've had mine for maybe 6 years now. It's probably one of my good items to do radiator work. Get the one with multiple vehicle attachments. So if needed be use it on other makes. You'd be surprised how much air is trapped in the coolant system.
Last if you go this route, and find no air trapped in your coolant. Then look into maybe the blend, or mix flaps not opening at the heater core. And yes on a normal day even in cold weather my heater is probably blowing extremely hot air at 75 deg, and above. In the summer once maybe the AC gets that mildew smell. After a drive I crank the heater to Max heat to try, and wipe out the bacteria.
https://youtu.be/zUpXgAJ1gjU
Thanks. I just ordered the funnel and will re-bleed the system on Friday. Also, thanks for confirming that the heater should be hot at 79.
You better check for head gasket leak. I have seen a few car at our shop having same problem and all turn out they have leak head gasket.
Failure radiator cap could also create the problem as well. If i were you, i would replace the radiator cap first, then check the pressure at the radiator cap (after the car parked for at least 2 hour) to see if you have any pressure or not. Let us know!!!
Failure radiator cap could also create the problem as well. If i were you, i would replace the radiator cap first, then check the pressure at the radiator cap (after the car parked for at least 2 hour) to see if you have any pressure or not. Let us know!!!
FWIW, my car is a 2012 IS350 with 57k on it.
03-09-19, 09:51 AM
#5
Just to update...the first time I bled the system seemed to have fixed it, at least for the time being. The heater has been blowing hot air from about 74/5-HI all week.
Also, I received the spill-free funnel yesterday and re-bled the system. I didn't notice any bubbles being released, but the funnel is super easy to use.
At this point, I will consider the issue resolved. If the heater starts blowing cool again, I'll update this thread.
Also, I received the spill-free funnel yesterday and re-bled the system. I didn't notice any bubbles being released, but the funnel is super easy to use.
At this point, I will consider the issue resolved. If the heater starts blowing cool again, I'll update this thread.
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