Dodge Neon Heating Problem
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Joined: Mar 2005
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Dodge Neon Heating Problem
Hey Guys
I have a 97 dodge neon 4 door sport, and for whatever reason, as I go faster then about 90 the heater inside the car stops blowing warm air and begins blowing frigged cold air... I've already replaced the thermostat thinking that that was the problem, but its still doing the same thing... When ever I slowdown when gettin off the highway of something it begins to blow warm again!
Please help me out as I've asked about everybody an no one knows that the heck is wrong!
Thanks!
Pawel
I have a 97 dodge neon 4 door sport, and for whatever reason, as I go faster then about 90 the heater inside the car stops blowing warm air and begins blowing frigged cold air... I've already replaced the thermostat thinking that that was the problem, but its still doing the same thing... When ever I slowdown when gettin off the highway of something it begins to blow warm again!
Please help me out as I've asked about everybody an no one knows that the heck is wrong!
Thanks!
Pawel
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Joined: Aug 2004
Posts: 319
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From: The birthplace of liberty
RE: Dodge Neon Heating Problem
Sounds to me like maby the radiator is clogged.
I say this because for some reason, the cooliant is staying in the radiator to long. This being the case, when you hit the highway, it's being cooled way down. When it reaches your heater core, it's cold.
I originally thought maby the thermaostat was staying open, but you said that you just did that.
Where does the temp guage in the car read?
I say this because for some reason, the cooliant is staying in the radiator to long. This being the case, when you hit the highway, it's being cooled way down. When it reaches your heater core, it's cold.
I originally thought maby the thermaostat was staying open, but you said that you just did that.
Where does the temp guage in the car read?
Joined: Mar 2005
Posts: 18
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RE: Dodge Neon Heating Problem
It 's not a radiator or cooling system related event.
Before you go to the trouble of checking the radiator/cooling system try this.
Turn your heater to full blast (both heat and fan speed), select air re-circulation, get on the highway where you can put it in 5th gear or get it into overdrive. Run it up to speed and listen to the sound of the fan. When the selector door is in "re-circulation" mode it generally makes a loud noise because the air is being pulled in to the HVAC system from inside the cab and is more audible. When the selector door is in the "outside air" position the noise is much less audible in the cab.
NOW... when you are cruising at highway speeds of 90 + MPH your foot is a good way into the throttle and thus engine intake manifold vacuum is low, this is key. Since the selector door is controlled by vacuum it may drift to the default position of "outside air" (which is the default) if your HVAC vacuum system has even a small leak.
If you are getting outside air into the HVAC system it will cool the output air temp a bit. I'm willing to bet your HEAT selector (i.e. temperature selector) is vacuum controlled as well, further I'll bet it defaults to COOL air when there is low or no vacuum available at cruising speeds or full throttle. It may be a combination of the temperature selector door and the air path selector door which is bringing in frigid air to the cab.
My 01 does this with regards to the air path selector. It only does it when I'm in 5th gear under mid to heavy throttle for a period of time (say 30 seconds or more) before i can hear the air path noise changing while the selector door moves from inside air to outside air. When I'm at highway speeds in 5th gear the engine vacuum is low and there must be a small leak so the door defaults to outside air.
Try the test and let me know if you can detect a change in the fan noise when you go from 0 to full throttle at highway speeds. Just make sure to maintain the speed for 30 seconds or more so the slow responding selector door has time to move and make the change in noise.
Eric
Before you go to the trouble of checking the radiator/cooling system try this.
Turn your heater to full blast (both heat and fan speed), select air re-circulation, get on the highway where you can put it in 5th gear or get it into overdrive. Run it up to speed and listen to the sound of the fan. When the selector door is in "re-circulation" mode it generally makes a loud noise because the air is being pulled in to the HVAC system from inside the cab and is more audible. When the selector door is in the "outside air" position the noise is much less audible in the cab.
NOW... when you are cruising at highway speeds of 90 + MPH your foot is a good way into the throttle and thus engine intake manifold vacuum is low, this is key. Since the selector door is controlled by vacuum it may drift to the default position of "outside air" (which is the default) if your HVAC vacuum system has even a small leak.
If you are getting outside air into the HVAC system it will cool the output air temp a bit. I'm willing to bet your HEAT selector (i.e. temperature selector) is vacuum controlled as well, further I'll bet it defaults to COOL air when there is low or no vacuum available at cruising speeds or full throttle. It may be a combination of the temperature selector door and the air path selector door which is bringing in frigid air to the cab.
My 01 does this with regards to the air path selector. It only does it when I'm in 5th gear under mid to heavy throttle for a period of time (say 30 seconds or more) before i can hear the air path noise changing while the selector door moves from inside air to outside air. When I'm at highway speeds in 5th gear the engine vacuum is low and there must be a small leak so the door defaults to outside air.
Try the test and let me know if you can detect a change in the fan noise when you go from 0 to full throttle at highway speeds. Just make sure to maintain the speed for 30 seconds or more so the slow responding selector door has time to move and make the change in noise.
Eric
