i have started having a problem with the heater when the car is idling the air coming out of the vents gets cold but while driving it gets hot again does anybody have any suggestions on what i should do about it?
__________________ Alot of stupidity goes a little ways...
it gets cold? as in is warm then gets cold or starts cold? if it starts cold when u turn the heater on it probly just needs to warm up. you cant turn on your car with a cold engine and just get hot air u gotta let the engine warm up, as with any car.
or the heater cutoff valve is stuck closed. the valve stops hot coolant from going into the heater core when the climate control **** is set to cool. since it is controlled by a vaccum maybe its stuck closed then once you reach higher rpms, while driving, its forced open letting hot coolant into the heater.
...isn't that just because it's cold outside? when you idle for one the fan slows down a bit and secondley your engine isn't making as much heat, so at idle the tempurature of the air coming out of the fan drops.
Location: I have a long-term loss of short-term memory, and I forget that I have it.
Rep Power: 283
Re: heat stops working
Possibilities come to mind:
Straight antifreeze, undiluted. Poor heat transfer ability. Should be a 50/50 mix, and test at around -30-40 below zero.
A water pump related problem (impeller fins eroded away, aftermarket water pump, etc.)
An air pocket in the heater core. A couple of things could have happened to cause this: The coolant got low enough to allow air into the heater hoses, or the head gasket is blown, and combustion gases are getting into the heater system. An overheat event could be related to both of these.
im starting to think that is just some air or maybe a vacuum line it had the head gasket replaced before i bought it so i dont think its that but the guy i bought it from didnt feel like changing the pump i guess so im not sure what that looked like also im not running straight antifreeze
just wondering what is wrong with aftermarket pumps?
__________________ Alot of stupidity goes a little ways...
water pumps almost never go bad, and if they did you would know it. if the turbine got stuck, you wouldnt have an engine right now after the timing belt came off. the only real issue waterpumps have is leakage of coolant from the seal. it has a metal turbine that doesnt wear out, and its turned by the belt. if the timing belt is moving, so is the water pump. you are doing all that work for nothing and the problem will not go away.
It's possible that when the HG went someone tried to put some stop leak junk in and now the heater core is like half clogged and only circulates when you get the rpms (and water pressure) up. Either that or there's an air pocket in the heater core.
1st thing I would do is bleed the system with the car on an incline so the radiator is above the heater core.
2nd thing would be to unhook both heater core hoses and try to flush it out with a hose.
I wouldn't think this would be a water pump issue.
Hi all.. I just registered because I saw this thread and might give some info on what all I have tried with this exact same issue. Right now, after spending $1k+ on the symptoms of this issue, I believe the problem is air in the cooling system. Keep in mind that I have taken the car to many mechanics during this process. Here is what I have researched. (Also, this was for a 2003 Honda Civic LX Sedan, specifically.)
1) Bent/broken fins in the water pump reduce efficiency. My original research indicated that if your water pump has plastic blades, this could be an issue. You'll find, that if you rev the engine to around 2k RPM, you will get heat. This indicates a poor water flow issue. (Replaced the water pump, was good for a day or two, and it was back.)
2) Stuck thermostat. Easy and cheap, replaced it (Still had the problem after a day or two)
3) Radiator cap. Since this is a closed system, if the radiator cap doesn't keep it sealed, it can suck air into the system as well as not allow the fluid back in. (Replaced radiator cap, still had the problem after a day or two).
(Note about the day or two. What it appeared, after each "fix", the coolant system was topped off and "burped". My heat work work great, but once air was re-introduced to the system, which took a day or two, I was back to no heat at idle.)
During all of this, I found that my engine began to overheat at idle. This was due to low coolant. Refilling the coolant would fix the problem, but was only a band-aid to a bigger problem.
4) Now.. for the scary part. Head gasket. In my case, I wasn't blowing water out the exhaust, I didn't notice (Key word, notice) air bubbles in my coolant, but I did come out one day to see my overflow tank hose blown off. My oil wasn't milky. From what I could tell, exhaust was going into the coolant to the point that it would increase the pressure, open the radiator cap (16lbs) and then blow the overflow hose off, which would then spew coolant out of the system, which would lead to air pockets causing this issue again. Quote to have this fixed was like $500 and that was in the case that the head didn't get warped from overheating and would cost even more. After spending the $1k+ already, I didn't want to take the chance of spending another $1k+. So, I purchased a product off the internet. Braced my gas pedal so it would run at 2k RPM so the coolant would stay flowing through everything, and ran it for 1 hour. That was about a year ago. So far, my car has not overheated since and the heat seems to be fine. I don't want to come off like I'm advertising a product, so I'm not going to mention it publicly, but it did work for me. At least, so far. I also understand this isn't a "professional" fix. But, the car is almost 9 years old, and in my opinion, not worth the risk of having it fixed "right".
I'm to the point that I know more about the cooling system in this car than I have EVER wanted to know. Hope something in here helped.
I've seen this problem a million times on the D17 engines, almost always ends up being a head gasket. when you replaced the water pump you bled air out of the system and as you drove it exhaust gases would leak into the cooling system creating air pockets causing a loss of heat, reving the engine speeds up the coolant flow and reduces liquid to air heat transfer giving you heat back. I've easily done 100+ head gaskets for this problem
I have seen poeple just use water to flush out the system, they have adapters to hook a hose up to..Either way when you do the flush you are still going to have to make sure you get the air out of the system.
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