Very little heat up front

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tripp82

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I have followed a number of threads on heat issues with the Montana.
Mine is a 2000 and I have full heat on the auxillary heater.The vehicle runs normal temperature.The controls of the heater have been checked and are working.We can't see inside the box but have verifed the blend door motor and shaft are working and moving and the heater core is flowing and has been flushed.Heat from the rear heater is 121 F and the defrost or floor is 71 F.The one item I haven't figured out is when the dash vents are selected in the cold temperature position there is extremely good air volume however when the selector is turned to full heat the volume goes to almost nothing.
Any ideas and how to I source a drawing of the inner workings of the heat box?
Help-Bruce::confused:
 
I had bad air flow on my van but still had heat it was the cabin air filter , it was really really dirty, once cleaned/replaced the flow was almost double. How ever you are describing no or little heat up front. If you are getting hot water into your heater core but little out perhaps the heater core is semi clogged ? First you have to verify the water into the core is hot . then proceed.
 
Not up front.We checked the airflow temp when set to floor or drfrost at 71 degrees F running at normal engine temp.The rear was 121 f at the same time.The heater core has not been removed but was flushed for 45 minutes and has water pushed through both directions.Its possible that the core is mostly plugged but will still flow water I guess but I don't know anyway to verify that without removing the core.The other thing that still puzzles us is that when set to dash vents the airflow is very good on the cold setting but reduces to almost nothing when the dial is moved to full heat.Short of tearing the entire dash out I'm not sure where to go next.
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Was this resolved?

New member...1st post. I have read about a dozen posts with these same symptoms of losing air flow when selecting heat but have not found anyone that resolved the problem.

I have 97 Montana Transport. With the temperature selector in cold position I get good air flow however I lose almost all air flow when I select full heat. If the heat selector is placed in the mid position I get some air but it is reduced. I also do not get defrost air hot or cold. I can find 1 electric and 2 vacuum actuators and they appear to be moving correctly. The inside/outside selector (Behind cabin filters) door opens and closes. Heater core gets hot and air blows through the core when I select heat. I have as many of the covers off that I can find, glove compartment removed.

Any ideas appreciated.
 
Regarding air flow, I remember in my 03 under the dash looking at the actuators and linkage and all the dampers , it was easy to follow the air flow and see which damper doors had to open and which ones had to close . I would think if you are loosing aior flow at certain settings that it would be a linkage problem, it would be easy to disconnect the linkage and work them by hand to experiment on which way they are supposed to be at but just remember where they go. I had to lube mine up where the linkage met the door bracket.
 
Hi!
-Perhaps clogged your heater and the core of the radiator. Need to rinse the entire system.
- Perhaps failure of the actuators . The actuators can also strip the little plastic gears inside the actuator. You can sometimes even hear a faint tick when this happens .
-Perhaps jammed thermostat . Check pipes that go to the heater. They should be hot.
-You get a blast of hot air if if you turn up a sharp left corner?And there is hot air for a second or two?. Then you have the air in the system.
 
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