Heater not working properly

1997 DODGE INTREPID
160,000 MILES • 3.3L • V6 • 2WD • AUTOMATIC
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INTRIPED1870
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  • 16 POSTS
I have had to deal with this problem for the last 3 years! (Winters) When I'm driving or parked at operating temperature i can turn the heater on and it blows hot around 10 seconds or so then gets cold. Turn it off and back on again i get the same results. I have repeated this procedure more times than I would like to say. I get the same results almost all the time, with one exception, if I stop somewhere and I switch from defrost to vents before I shut the car off. Then get back in and start it, it has blown hot and stayed hot a couple of times. If I go to any other settings, it goes back to luck warm or cold again. I was just lucky those times, I think. (My opinion) Turn on and it's warm 10 seconds then goes cold. Turn off and back on and it's warm again 10 seconds then cold again. Bottom line it barely keeps the windshield defrosted but it won't keep anybody warm. I have changed the thermostat and checked the heater core hoses they seem to be hot. I have got the dash laying in the front seats of my car right now because I initially thought it was my heater core and bought a new one. On this car I still have to remove the whipper unit, A/C lines and more less the HVAC unit completely out. Is it a heater core issue or would it be a Blend door actuator issue?
PS: also changed the climate controller.
Nov 23, 2021 at 5:59 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
Hi,

This could be a few different things. First, if the engine is reaching operating temperature and the engine coolant is full, the first suspect based on your description is the heater core is partially plugged.

On the other hand, the air temperature in the vehicle is controlled by what is called a blend air door. There are actuators that move the doors to allow different amounts of heat or A/C to enter the vehicle.

If you can, try something for me. Drive the vehicle with the heater on. When the heat is working normally, open the hood and feel both heater core hoses. Both should be hot.

Close the hood and keep driving. When it cools off, stop, open the hood, and feel the hoses again. Is one a lot cooler than the other?

Let me know what you find. Also, here is a link you may find of interest:

https://www.2carpros.com/articles/car-heater-not-working

Also, let me know if the vehicle has automatic climate control and dual climate control.

Take care and Happy Thanksgiving.

Joe
Nov 24, 2021 at 2:28 PM
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INTRIPED1870
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It has rear air that runs through the center console with only the front climate control.
Nov 27, 2021 at 1:58 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
Hi,

Okay, did you try testing if the heater core hoses are getting hot? Also, does the vehicle have dual climate control? In other words, can the driver and passenger select different temperatures?

Let me know.

Joe
Nov 27, 2021 at 2:43 PM
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INTRIPED1870
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I couldn't start it at that time because most of or all the wiring in the dash was all unplugged and the steering wheel was in the floor boarded of the car. I probably get it where I can start it today and try it. There shouldn't be a problem with it with me putting a new one in it. I will let you know this afternoon if weather permits.
Nov 27, 2021 at 5:41 PM
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INTRIPED1870
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Well, I'm a little late but I got it done a couple hours ago. The heater problem is no more, problem solved. That thing will run you out. This is my opinion, but I believe it was both blend door actuator and the heater core. All I know is that I've wanted 3 years for this and it's finally done. I want to thank you for all the advice. Had it not been for that I would have put it back together without a new heater core. Thanks Joe
Nov 28, 2021 at 10:12 AM
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JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
Hi,

I'm glad to hear it's fixed. Also, thanks for letting me know because it will likely help others in the future.

Take good care of yourself and please feel free to come back anytime in the future.

Joe
Nov 28, 2021 at 10:49 AM
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