# NO HEAT!!



## 2drcam (Oct 7, 2003)

ok. i have recently acquired a 95 altima w/ 150k. when I bought it he said there was no heat. so, I tried the basics first. I replaced the thermostat. that didn't help, next i went and replaced the radiator. that didn't work. now before i go and rip this car apart can someone give me some input as what it could be. 
when the car runs @ about 2-3000 rpm the car has heat. there is no white smoke coming out of the exhaust what so ever. and when i fill the radiator up it seems like there is a lot of air in the system and the fluid and air spew out of the radiator. the temp. gauge reads normal and does not overheat at all. my ideas could be a heater core or water pump. and if worse comes to worse the head gasket. 

any help would be greatly appreciated.

thanks


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## Asleep (Jan 19, 2003)

2drcam said:


> ok. i have recently acquired a 95 altima w/ 150k. when I bought it he said there was no heat. so, I tried the basics first. I replaced the thermostat. that didn't help, next i went and replaced the radiator. that didn't work. now before i go and rip this car apart can someone give me some input as what it could be.
> when the car runs @ about 2-3000 rpm the car has heat. there is no white smoke coming out of the exhaust what so ever. and when i fill the radiator up it seems like there is a lot of air in the system and the fluid and air spew out of the radiator. the temp. gauge reads normal and does not overheat at all. my ideas could be a heater core or water pump. and if worse comes to worse the head gasket.
> 
> any help would be greatly appreciated.
> ...


lol, man you are a mechanics DREAM!  youre spending a lot of money and time on the "basics". now, im not knocking you for doing the work, im applauding that, its just that, replacing the thermostat and radiator would have been last on my list since your temp gauge says that everything is ok and you're not overheating. now, lets really get to the basics. do you know that the temp selector is working? im willing to bet that its not... know why i think that? because you said that you make heat when the engine is revving at about 2-3000... with that said, im thinking that at those rpms youre pulling enough vacuum to close the valve needed for your hot water valve to work... behind the intake manifold and on the firewall around cylinder 3 or 4, youll see a black "thing" for lack of a better word with a cable going to it and a spring attached to it and a heater hose on each side. this is your hot water valve. you need to run the engine and have someone move the temp selector inside the vehicle. if it doesnt move, then either the valve is stuck or you are losing the signal, im not sure if its electrical or vacuum though... being that it works at certain rpm ranges though, ill bet its vacuum. do this first and lets see what you get. now for the air in your cooling system. look above and behind the thermostat housing. do you see the little bolt above the ground strap? thats the bleeder screw for your coolant system. while the engine is COOL, remove the radiator cap and then the bleeder screw and leave it off until you get water flowing from it. once that happens, reinstall the screw and tighten, but do NOT overtighten it, it will break if you do. replace whatever water in the radiator you need to and reinstall the cap, now your system is bled.


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## 2drcam (Oct 7, 2003)

AsleepAltima said:


> lol, man you are a mechanics DREAM!  youre spending a lot of money and time on the "basics". now, im not knocking you for doing the work, im applauding that, its just that, replacing the thermostat and radiator would have been last on my list since your temp gauge says that everything is ok and you're not overheating. now, lets really get to the basics. do you know that the temp selector is working? im willing to bet that its not... know why i think that? because you said that you make heat when the engine is revving at about 2-3000... with that said, im thinking that at those rpms youre pulling enough vacuum to close the valve needed for your hot water valve to work... behind the intake manifold and on the firewall around cylinder 3 or 4, youll see a black "thing" for lack of a better word with a cable going to it and a spring attached to it and a heater hose on each side. this is your hot water valve. you need to run the engine and have someone move the temp selector inside the vehicle. if it doesnt move, then either the valve is stuck or you are losing the signal, im not sure if its electrical or vacuum though... being that it works at certain rpm ranges though, ill bet its vacuum. do this first and lets see what you get. now for the air in your cooling system. look above and behind the thermostat housing. do you see the little bolt above the ground strap? thats the bleeder screw for your coolant system. while the engine is COOL, remove the radiator cap and then the bleeder screw and leave it off until you get water flowing from it. once that happens, reinstall the screw and tighten, but do NOT overtighten it, it will break if you do. replace whatever water in the radiator you need to and reinstall the cap, now your system is bled.


ok, first off thanks for your help asleep. I did both of of your suggestions and the radiator had only a slight amount of air in the system. Next I checked that hot water valve and it is functioning properly. however i'm still getting that spewing out of the radiator. is this normal on these motors? btw I also found that the radiator cap gasket was broken and that was causing some problems, but now it's fixed. anymore suggestions would be great.

thanks


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## Asleep (Jan 19, 2003)

at this point, we know its not a blocked radiator since you replaced it already. the cap, by being broken, was not allowing the coolant to hit the correct boiling point so its good that you replaced it. the spewing is somewhat normal - when the thermostat is open. im going to assume that the water point is working right now and move to the heater core. its located somewhat behind the center console. what i need to know is if the heater core is heating up at all. it could be blocked internally. you can check it from the engine compartment however by touching both heater hoses behind the engine after the car has already reached operating temperature. one will be the inlet and the other the outlet. if the core is blocked really badly, one of the two hoses will be cooler than the other. lets do this step and see what you get. obviously, if one is cooler, the core could be blocked and you know what you have to do. if theyre both hot, we'll just assume that its working.


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## 2drcam (Oct 7, 2003)

ok, before I go on the heater core let me add a couple of things. about 2 days ago the car had great heat (when the broken radiator cap was in) when this was going on the car would steam and you could hear bubbling in the overflow container and there was no thermostat in. yesterday I put the thermostat back in and put the new radiator cap in then the car began to overheat, but it had very nice heat. It would only overheat when I was driving it. when I was stopped the temp gauge would begin to go to normal. So now i'm totally baffeled. any suggestions?


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## Asleep (Jan 19, 2003)

did you by chance install the thermostat backwards?


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## 2drcam (Oct 7, 2003)

that's what i'm trying to figure out. which way does it have to face?? is the spring in toward the block or out?

thanks


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## Asleep (Jan 19, 2003)

spring towards the block.


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## Asleep (Jan 19, 2003)

did this get resolved?


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## 2drcam (Oct 7, 2003)

whoops. sorry for not responding. i have not resolved it yet. now the car overheats w/ the new thermostat in. HELP?!?!?


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## KA24Tech (Feb 2, 2004)

The cooling system and radiator cap should be pressure tested. Also the coolant level should be topped off and the system should be bled. The cooling system air bleed is the bolt on top of the water neck just below the distributor. Check the operation of the water pump and make sure it does not have seal failure. The seal going ou is evidenced by the presense of coolant or crusty residue in the weep hole on the bottom of the water pump.


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## repus (Apr 3, 2007)

Asleep, looks like you know yur stuff... Can you help... Water/Coolent leaks from what seems to be the back of the engine close to the firewall. Also no Heat... Car was overheating due to no water.. had to pull the Thermostast on side of the road to get water flowing to get home( had my tools w/ me)... Are ther any water hoses back there... Heater maybe.....


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## Asleep (Jan 19, 2003)

there are heater hoses back there along with freeze plugs on the block. 
you might want to check and see if any of them are leaking.


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## 93SE-Qc (Oct 5, 2007)

Hi , here is the side of the thermostat ;



-I was having this problem too last year , I replace the blower resistor (only worked at 4th speed) off course it didn't make any more or less heat ... 

-I change the thermostat ... no change ! Still cool air only 

- I flushed/rinse the heater core , disconect both hose and flush with the hose garden , I did take care for water to goes anwhere . 

- Tadam !! hot air was coming out :woowoo:


BUT ... same story again this automn ... I decide to rince again the heater core but before I asked my girlfriend to move the cold/hot selector in the car while I was watching the cable work in the hood ... error the cable was stuck in kinda rust or something . 

- I grab a WD-40 can and spray it over the cable and made it move (my gf still in the car) , I helped the cable a little . ... tadam ! Hot air is back up for another year ! lol 

It's the cable near the spring above the black unconnected hose 



Hope this help !


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