Heater problem

[highrolla7]

Hello,
just purchased a 98 zx2. Runs great and is a pretty fun car. The only problem with it is the temp gauge doesnt work and heat doesnt get all that warm ( i live in iowa, very important!!). Anyway, I drove it around to see if the heater would "kick on" and didnt. So, my brother said "floor it" and so I did. All of sudden the heat got real hot and the temp guage worked. Then it went out again. So, i can tell that the temp gauge and heater must be connected and whatever is going out, has something to do with these 2 things. I was told water pump or heater core. Any other ideas out there. The temp gauge does work sometimes as well as the heater, and then it just "dies out" and the temp gauge drops. Please help, T. J.

[KimMG]

Check thermostat to make sure it is closing when it is suppose to. Worn vanes on a water pump can limit coolant circulation. Check coolant level. If coolant level is low, then there is no coolant for the temp sensor to measure. Feel both hoses going to the heater core and see if they are both hot. If one is cooler than the other, then the heater core may be clogged or restricted.

[highrolla7]

Originally Posted by KimMG

Check thermostat to make sure it is closing when it is suppose to. Worn vanes on a water pump can limit coolant circulation. Check coolant level. If coolant level is low, then there is no coolant for the temp sensor to measure. Feel both hoses going to the heater core and see if they are both hot. If one is cooler than the other, then the heater core may be clogged or restricted.

Thanks for the great info. I will try those things. Right now, the heater starts out cool, then all of sudden will get very hot, and the temp guage will start working, then for no reason, it will get cooler and temp guage quits working. Very strange! Thanks again, it will give me something to start with. Take care!!

[merlin2]

Hi Fellas:

I've been having a similar problem: heater works sporadically and responds to random control inputs. In other words - it works great sometimes, not at all other times, but if I keep turning it on and off, change the fan settings, temperature settings or defrost, feet, combo, dash heat settings - it will strat to work - but there is no consistent setting that always works or never works. I've replaced the thermostat - that was the first thing. Haven't checked whether the heater core is blocked...but here's the weirdest part....some of the time after I reach op temp and I turn the heater on....the temp indicator will drop off rapidly to pegged out at zero and the heater blows cold. That's when fiddle the controls and most often get it to work. Lately though, it sometimes reads op temp but still blows cold. Temperature sensor problem??????

I live in the interior of British Columbia and we get lotsa minus wether over the winter...need that heater!

[highrolla7]

Originally Posted by merlin2

Hi Fellas:

I've been having a similar problem: heater works sporadically and responds to random control inputs. In other words - it works great sometimes, not at all other times, but if I keep turning it on and off, change the fan settings, temperature settings or defrost, feet, combo, dash heat settings - it will strat to work - but there is no consistent setting that always works or never works. I've replaced the thermostat - that was the first thing. Haven't checked whether the heater core is blocked...but here's the weirdest part....some of the time after I reach op temp and I turn the heater on....the temp indicator will drop off rapidly to pegged out at zero and the heater blows cold. That's when fiddle the controls and most often get it to work. Lately though, it sometimes reads op temp but still blows cold. Temperature sensor problem??????

I live in the interior of British Columbia and we get lotsa minus wether over the winter...need that heater!

Yeah, that kind of sounds like what mine does. It will blow out cool air instead of hot. I never did try to mess with the controls though. I just know it has a mind of its own. Too cold here to work on it, so driving my back up car now. Keep in touch and if you do happen to fix it, post here please, and i will be doing the same. Thanks

[merlin2]

Thanks highrolla...I note that KimMG advises re: worn vanes on water pump. Now wouldn't that also result in higher indicated operating temp during hot weather? You see, this condition started in my car after it mysteriously lost all coolant and overheated. Fixed all that, but the heater problem cropped up after that. Thermostat replaced. Ran through one entire winter with intermittent but ultimately salvageable heat. Had a major tuneup and and all fluids replaced. Heater ran fine (particulary in warmer weather). Ran great during the first cold snap as well. Then problems arose once more, recently.

Okay, that's a roundabout way of getting to this question - could the original overheating have damaged the water pump vanes? Could that have also or aditionally damaged the blend control???? Or is this a problem with coolant leaking somewhere where I don't see it dripping under the car and the low level causes heater core to be short of liquid?

Where could the coolant be going. other than visibly leaking, which it isn't??????

M2

[Markb873]

Sounds like you got a 160 degree thermostat in the car. Which autozone will sell you first. Make sure you have a 190. The guage doesn't register untill about 170 so thats why you didn't see any movement untill you generated some heat. Plus the heater hose comes after the radiator so thats why you felt no heat. 160 degrees gets real cold real fast flowing through a radiator in iowa.

[highrolla7]

merlin,
have you found a solution to yours yet? I know we have to have the same problem, sporadic heat and temp guage dropping to zero, just wonder if you have found a solution yet. It has been too cold to work with it here, so Im stuck driving a different car for now.

As for the thermostat, im sure i have the 190 degree because it will turn on and off no matter how long it is driven. I took it on an hour trip, started out cool, then got real hot for a while, then dropped to a cool/warm, then back to hot again. As it is doing this the temp gauge will drop and rise with it..... thanks for the advice though, not saying your wrong, just throwing out ideas. Take care.

[merlin2]

Originally Posted by highrolla7

merlin,
have you found a solution to yours yet? I know we have to have the same problem, sporadic heat and temp guage dropping to zero, just wonder if you have found a solution yet. It has been too cold to work with it here, so Im stuck driving a different car for now.

As for the thermostat, im sure i have the 190 degree because it will turn on and off no matter how long it is driven. I took it on an hour trip, started out cool, then got real hot for a while, then dropped to a cool/warm, then back to hot again. As it is doing this the temp gauge will drop and rise with it..... thanks for the advice though, not saying your wrong, just throwing out ideas. Take care.

Hey Highrolla7:

I think i have the problem licked....so far so good. I took off the rad cap, just to make sure my coolant level hadn't dropped off too far. There was a pressure relief whoosh and a big burp in the overflow cannister. I topped up the fluid....very little actually....and it's been working like a hot damn (pun intended). Seems like a very small drop in rad fluid creates a low pressure situation.... fluid can't circulate through trhe heater core and bingo ....no heat. some of the other symptoms are still a bit mysterious but can probably be explained by the location of the temperature sensor and the heater core etc. So give that a try.

Merlin2

[highrolla7]

Originally Posted by merlin2

Hey Highrolla7:

I think i have the problem licked....so far so good. I took off the rad cap, just to make sure my coolant level hadn't dropped off too far. There was a pressure relief whoosh and a big burp in the overflow cannister. I topped up the fluid....very little actually....and it's been working like a hot damn (pun intended). Seems like a very small drop in rad fluid creates a low pressure situation.... fluid can't circulate through trhe heater core and bingo ....no heat. some of the other symptoms are still a bit mysterious but can probably be explained by the location of the temperature sensor and the heater core etc. So give that a try.

Merlin2

Merlin, Thanks for the help. I will make sure that it is topped off. If this is the problem, that would have to be the easiest fix ever for a vehicle. Thanks again.... keep me up to do date

[merlin2]

Originally Posted by highrolla7

Merlin, Thanks for the help. I will make sure that it is topped off. If this is the problem, that would have to be the easiest fix ever for a vehicle. Thanks again.... keep me up to do date

Hey, like I said so far so good. Remember though that you have to top off the rad itself....I was always looking at the overflow cannister and topping up there - not good enough. Doesn't release the vacuum created by dropping levels in the rad. Where does the rad fluid go in the absence of a leak??? Still a problem that someone else out there may be able to address....

Keep on rollin high

Merlin2