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Hi all, winter is here and the heater decided to stop working. A few weeks ago I noticed that the car was not blowing hot air as fast as it used to do. Then, the car started to blow only warm air and after a while, it would blow hot air (in the hot setting, of course). Now it is blowing cold air even in the hottest setting. If I play with the **** a little bit, switching from hot to cold several times, it would start blowing hot air but few mins and then goes back to cold air and a few minutes later goes back to hot again I could not find much info using the search option...

Any suggestions?

Thanks,

*****

 
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ok, so as soon as I posted the first post, one suggestion from an old thread showed this answer:

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The AC will not give warm air
AC is supposed to make the air cold, no?

Quote:
The heat is intermittent;it will put out heat on occasion and then drop back to cold.
Fan blows continuously, therefore not a fan problem....
2 theories, one is much more likely than the other...

Observe how it acts, observe what you can see:
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IF your intermittent heat follows this pattern:
"Heat is hot while driving but cools off at stops and idle....."

My nickel bet says the coolant level is low because the head gasket is blown.
(If there are no other external leaks such as hoses or water pump.)

Loses heat because the heater core has air trapped in it. Coolant may be low in the radiator, the overflow reservoir is way too full or has puked all over the right front area from overflowing.

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IF your intermittent heat loss does NOT follow that pattern above:
The other possible cause would be that the blend door actuator is moving on its own, and you should be able to observe the position of the heater core water shutoff valve in the engine compartment to verify whether this may be the case or not.
The cable for the water valve is mechanically linked to the blend door mechanism/linkage, so if it is open the actuator must be in the heat position, and if it is closed the actuator must be in the cold position.

Open the hood and check out its position when the heat works, compare to when the heat doesn't.

HTH

so, my car's pattern does not follow the first scenario, so I am assuming that the blend door actuator is moving on its own (you can actually hear a sound like some sort of mechanism is moving right before the air changes temperature). I will check the position of the actuator and report back. BTW, where is the actuator located? is it easy to find?

*****

 
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You should also check coolant levels in the radiator and reservoir tank. Blown head gasket will not always give you heat while driving and cool off at stops.

 
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Check coolant levels rad + reservoir immediately, pay attention to your temperature gauge as well

 
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Yep happened to me too. I was ignoring it because i live in the south... a few weeks later my temp gauge climbed at traffic lights and slow speeds... i was pissing in my pants!

 
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check for leaks before you start throwing parts at it, if coolant is leaking out of hose connections it should leave deposits

 
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check the rad for leaks as well

 
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What's the coolant level in the reservoir? If your head gasket was bad then coolant in the radiator would be pushed into the reservoir, possibly overflowing out the top.

 
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So the head gasket isn't blown (yet), hopefully having low coolant didn't damage it

 
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if the Engine didn't overheat then there is no reason for it to damage the headgasket.

 
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These cars are very sensitive when it comes to head gaskets, and the temperature gauge isn't exactly accurate, it gives you a rough idea.
It could say it's in the normal zone when it's actually a little high or low.

 
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Prove it, figure out exactly where it leaks first. THEN decide what really needs fixed, and how to go about it.

 
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so, I couldn't find where the leak is... I think that the residue I found under the reservoir area is old oil from a leak that the valve cover had (I fixed it two years ago). I did not notice any leak coming from the hoses or the bottom of the radiator. I did notice that on one side fo the top of the radiator there was some deposit of green stuff similar to limescale from showerheads. What do you think? should I get the system tested? Now I remember over a year ago the coolant was pretty low; I filled it up and since I could not find any leaks I left it as that and I forgot about it. I wonder if the car has been leaking just a tiny bit and it reached a low level (I don't remember the last time I checked the water level...)

 
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can you attach a picture of that stuff?
it's probably leaking there, they tend to develop pinholes at the seams
new rads are pretty cheap, denso is the oem brand

 
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that works

 
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Regular checking and keeping it full should not be difficult, that solves the heater issue for now and gives you plenty of time to figure out if it's really leaking at a significant rate, hopefully discover where it is leaking sooner or later, and decide what to do about it.

You can probably borrow a cooling system pressure tester from a parts store if you are ambitious.....lol

 
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Pics: You will have to figure out if there's a slow but active leak there or if that's just residue leftover from whenever the radiator cap had been removed and liquid spilled.

Edit: Pressure test would show if the plastic tank is cracked....so might filling it and watching it.

 
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That looks like it's leaking,
however it would be a good idea to test it for leaks to make sure

 
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I have been checking the coolant level and is going down consistently. I will rent the pressure tester from autozone. Any suggestions/tips while using it?

*****

 
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I think it won't matter if you test hot or cold, but it's safer to remove the radiator cap while the engine is cold and the radiator has no pressure in it (you can judge this by squeezing the radiator hose)

Do NOT exceed the pressure rating of a typical radiator cap (13-16 psi)
Do NOT run the engine with the tester installed on the radiator

 
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I found the proof! As soon as I put pressure in the system (16ish psi) I heard drops. Honestly, I am sort of relieved that it was the radiator and not something else (worse). So now I will change the radiator. I found a Denso radiator made in china or taiwan for 60 or so dollars. The OEM is 3 times more expensive. Do you guys think I can use the made in china one? should I replace the overflow tank as a preventative measure? The hoses appear to be ok but when I replace the radiator I will check them and reasses.

 
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It's should be ok, just inspect it carefully and keep an eye on the level for the first couple weeks.
Someone here replaced their rad recently and the new one showed up bent, so they had to order another one