No heat out of HVAC and car Overheating.

D-Railed_Neon · Post by **D-Railed_Neon** » Mon Nov 07, 2011 10:48 pm

Like the post says. I have no heat coming out of the vents when I turn the heater on, and the car overheats in about 10mins flat with or w/o and air turned on. I did some searching and the boards say, coolant level, thermostat, temperature sensor are the best places to start. Coolant level is good, couldn't get the cap off of the thermostat housing. (it was 40 degrees ,9pm at night, and pouring down rain

) and where do I find the temp sensor?

Any other possible causes, advice or direction would be a God-send right now. HELP!!!

Thanks guys.

mwenzlick · Post by **mwenzlick** » Mon Nov 07, 2011 11:19 pm

maybe the thermostat isnt opening? if you can take the thermostat housing apart and drop the thermostat into a pan of boiling water and see if it opens.

is the coolant level good inside the overflow tank, and if you manage to get the radiator cap off, is there coolant in the radiator?

I am by no means an expert, just throwing ideas out there.

D-Railed_Neon · Post by **D-Railed_Neon** » Mon Nov 07, 2011 11:27 pm

ideas are appreciated! Yes coolant in overflow is full and.....our cars have radiator caps???

mwenzlick · Post by **mwenzlick** » Mon Nov 07, 2011 11:30 pm

sorry, i meant the cap on the thermostat housing

Post by **occasional demons** » Tue Nov 08, 2011 12:42 pm

You likely have an air pocket. The heater core flows coolant constantly, so if there is air trapped, it will not flow to the core. If the t'stat has no bleeder, you may need to loosen the housing to let air escape. The t'stat will also not open soon enough if there is no coolant in the head. The temp sensor is on the left side of the head. (Battery side)

D-Railed_Neon · Post by **D-Railed_Neon** » Tue Nov 08, 2011 2:01 pm

Occasional demons you just made me smack myself in the forehead.

What happened was I installed my new intake manny and in the process bumped the t-stat housing cap loose. Drove home and noticed some steam coming from under the hood when parked it at home that night about 20 mins away from the garage. TEMPS WERE NORMAL. Popped the hood and saw the cap was loose and some coolant had sprayed out. Tightened the cap with the engine still hot, poured some fresh coolant into the overflow and went inside. 2 hours later (keep in mind it was 8pm now and 40 degrees in omaha) I drove to an appointment. It overheated on the way there and once again on the way out. It is plausible that having the cap off hot and then closing it and allowing the engine to cool trapped air in the system. Does that makes sense to you?

Post by **occasional demons** » Tue Nov 08, 2011 7:53 pm

It should have pulled coolant from the expansion tank, if the cap is working properly. Air still could have been trapped in there tho.

With the engine cool, remove the cap and check the level again. If you took note of the level in the expansion tank, see if it is lower. If it did not drop, the cap may not have been seated, or the seal is bad. It relies on the cooling engine to create a vacuum to draw the coolant back in.

BoKu · Post by **BoKu** » Wed Nov 09, 2011 6:30 pm

In my experience, the Neon motor is not particularly fussy about bleeding and air bubbles. But that's just my experience in refilling the system after changing a radiator and a heater core and a thermostat (not all at once; three separate maintenance episodes). At least, not fussy like the Subaru EJ25, now there's one that needs its burping.

Just last week I had the thermostat in my 2003 SE break; fortunately it failed open and not closed. But it does show that thermostats will eventually fail. I'd remove the thermostat cover, and then the thermostat and give it a good looking over. Well, actually I'd just replace it, they're only ten bucks or so. Then I'd give the old one a good looking over before I tossed it.

If the thermostat didn't yield any clues, I'd double-check that the fans turn on as they should. Then I'd check to make sure the radiator isn't plugged up or filled with ATF from a leaking ATX cooler. Then I'd start to worry about a blown head gasket or cracked head or block, pretty much in that order.

Post by **occasional demons** » Wed Nov 09, 2011 8:11 pm

It all comes down to the t'stat, if it has a bleed hole or not. Without the hole, they can be a pain to get the air out without getting things warmer than you would like. With the jiggler valve/bleeder, all you need is patience when filling the system.

D-Railed_Neon · Post by **D-Railed_Neon** » Fri Nov 11, 2011 2:03 am

sure enough bad t-stat. Up and rolling again. also replaced hoses and clamps and did a full flush

Nice and cool now. Thanks for the help and advice. Next time it happens (hopefully thousands of miles from now) I'll know what to expect and what other possible culprits may be. Thanks again 2GN

NEON PARABOLA · Post by **NEON PARABOLA** » Fri Nov 11, 2011 9:21 pm

glad you're up and rollin' again bro!

D-Railed_Neon · Post by **D-Railed_Neon** » Fri Nov 11, 2011 10:25 pm

Thanks man, good to have my blue baby back