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Need ideas on this problem. After about an hour of driving with air conditioning on, airflow in cab drops to nearly zero. I can still hear the cabin fan still working, but little to no airflow. If I turn off the AC for a few minutes, it works okay again, but only for a few more minutes. Changing from recycle to external air feed and back doesn't change things. On shorter trips the problem doesn't manifest itself, only after about an hour of constant running.

Any ideas?

Thanks.
 

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Sounds like evaporator icing: ensure drain is clear; run fan fastest/faster speed and select warmer temp if too cold.
 

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Need ideas on this problem. After about an hour of driving with air conditioning on, airflow in cab drops to nearly zero. I can still hear the cabin fan still working, but little to no airflow. If I turn off the AC for a few minutes, it works okay again, but only for a few more minutes. Changing from recycle to external air feed and back doesn't change things. On shorter trips the problem doesn't manifest itself, only after about an hour of constant running.

Any ideas?

Thanks.
Flealami,

I'm sorry to hear about your concern. Did this begin intermittently? Do you park outside and is there an opportunity for any debris (Leaves/needles) to fall into the vent system?
 

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No, the problem is not intermittent, in that it happens every time I drive over an hour. Never happens on shorter trips.

The car does stay outside and there could be debris accumulated, but why would any blockage only show up after a long drive and not short ones?

Somebody mentioned the possibility of ice forming after a long drive and blocking path of the air.


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Ice is slowly forming on outside of evaporator core/fins, strangling air flow thru it; when AC is then turned off, evap temp rises toward ambient and melts the ice and it will work again; till AC is turned on again and it refreezes.
... High humidity and restricted air flow are definitely factors; as are low/slow fan speeds when temp selector is set to cold.

Set fan to high/fastest speed, set temp selector warmer if you need to; see if issue goes away. ... Ensure drain is clear.
 

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Thanks, I will try that.
After you "prove" to yourself that's the issue, try turning fan speed down a notch at a time, and try again; to see how much the system tolerates (note ambients/humidity and both settings). Good luck, and post results for others.
... If/when it starts icing, quickly turn off AC to allow evap to warm and allow ice to melt.
 

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Mine will do the same thing. Started last year and only does it on long trips. I originally thought it was icing, but I don't believe that's the case. Seems like some sensor issue but not sure. When it slows down I turn the AC switch of and change airflow to defrost or some selection other than the AC ones. Takes about a minute or so and the air speed picks up again, then can switch AC back on.
 

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I'm having this problem on an 08 ram 2500 diesel. I'm suspicious of a mouse nest went through the system and clogged the evaporator. I removed the fan and squirl cage, and reached up in. The evaporator felt fuzzy. I've tried a shop vac. Didn't really seem to help. I'm thinking compressesd air to the other side and shop vac on the fan side. I'll have to cut a hole for the air gun. Any suggestions/ideas. KB
 

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I'm having this problem on an 08 ram 2500 diesel. I'm suspicious of a mouse nest went through the system and clogged the evaporator. I removed the fan and squirl cage, and reached up in. The evaporator felt fuzzy. I've tried a shop vac. Didn't really seem to help. I'm thinking compressesd air to the other side and shop vac on the fan side. I'll have to cut a hole for the air gun. Any suggestions/ideas. KB
Could study FSM and/or junkyard HVAC, so you know door locations and their mode positions, and drain location/angle would help.
... From the little I've seen, heavy ish and hard or impossible to move debri/leaves accumulate at bottom of evap, upper evap likely just fuzz andddddd

DK 3G; "IF" drain is between blend door and evaporator, could try comp air in the drain with shop vac on fan side of evap (close? blend and some other doors, may have to disconnect certain actuator/s to close, and/or plug outlets).
... Consider using a 2nd or 3rd comp air hose to increase air volume as evap is big; another shop vac "blowing" could supply this positive pressure volume thru an outlet.

Beware: on some vehicles, messing with panel outlets/louvers can activate airbags unless they're disabled. IIRC 2G ram has this warning.
 
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