weak flow through HVAC vents
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weak flow through HVAC vents
2008 F-250 XL/5.4
Truck has consistently weak air flow out of all interior vents. Mode and blend doors appear to be functioning properly. Defrost vents seem to be more restricted than others flowing almost no air at all. Recirculating improves air flow some but not much. I used a long blow gun and a vacuum attachment to clean out the HVAC inlet in the cowl (which did have some pine needles and such built up on it) and found no noticeable difference in flow. I am assuming the inlet and possibly the heater core and evap. core are simply plugged up with dirt and that I will be removing the dash to deal with this. Just want to make sure I'm not overlooking something before I do.
This vehicle is used for Wildland Firefighting and sees a lot of dust/dirt and a lot of A/C use.
No noticeable difference in flow whether at max heat or max a/c.
Truck has been acting this way since around the 25,000 mile mark.
Thanks in advance.
Truck has consistently weak air flow out of all interior vents. Mode and blend doors appear to be functioning properly. Defrost vents seem to be more restricted than others flowing almost no air at all. Recirculating improves air flow some but not much. I used a long blow gun and a vacuum attachment to clean out the HVAC inlet in the cowl (which did have some pine needles and such built up on it) and found no noticeable difference in flow. I am assuming the inlet and possibly the heater core and evap. core are simply plugged up with dirt and that I will be removing the dash to deal with this. Just want to make sure I'm not overlooking something before I do.
This vehicle is used for Wildland Firefighting and sees a lot of dust/dirt and a lot of A/C use.
No noticeable difference in flow whether at max heat or max a/c.
Truck has been acting this way since around the 25,000 mile mark.
Thanks in advance.
Tuned
Joined: Aug 2007
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From: CO Mnts
Honestly I'm not certain...but do these trucks have a cabin HVAC air filter which seems present on a lot of modern vehicles?
If airflow was reduced at 25k miles, that is the first thing I would check for, a dirty/clogged cabin air filter.
If airflow was reduced at 25k miles, that is the first thing I would check for, a dirty/clogged cabin air filter.
Hotshot
Joined: Jan 2004
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From: St Louis
Cabin air filters were a dealer installable item but they were not factory original. However, a restricted cabin air filter will ONLY affect the flow of air from outside. It won't restrict airflow when in recirculate mode.
You have to find the portion of the system where all airflow must pass through. That would be the evaporator core and the housing where the blower resides.
You have to find the portion of the system where all airflow must pass through. That would be the evaporator core and the housing where the blower resides.
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thank you for the replies.
No cabin filters. I have removed the blower motor and observed it's operation. No signs of blockage visible from the port for the motor. No material in the hamster wheel whatsoever. Swapped in a motor from another rig and no change. Motor makes 4 distinct speeds. Mode switch directs air to selected vents and selected vents only. Just no damn flow.
There's actually two trucks under my care with this same issue.
Any info on these cabin filters available through the dealer?
Are they located in the cowl or in the HVAC housing?
I was considering a custom setup to stave this off in the future but bolt on would be nice. .
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thank you for the replies.
No cabin filters. I have removed the blower motor and observed it's operation. No signs of blockage visible from the port for the motor. No material in the hamster wheel whatsoever. Swapped in a motor from another rig and no change. Motor makes 4 distinct speeds. Mode switch directs air to selected vents and selected vents only. Just no damn flow.
There's actually two trucks under my care with this same issue.
Any info on these cabin filters available through the dealer?
Are they located in the cowl or in the HVAC housing?
I was considering a custom setup to stave this off in the future but bolt on would be nice. .
Senior User
Joined: Jan 2013
Posts: 105
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From: Suffolk, VA
I worked on a 2005 F250, 5.4 from up north (New Jersey) and it had a similar problem. Ended up being a rusted heater core, weak blower motor and rusted/burned up blower motor resistor. Sounds like you have a plugged heater core, especially since you found some pine needles in the intake. I haven't heard of anyone doing a cabin air filter mod but I bet the dealer version isn't the only one out there.
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From what I gather ford did and maybe still does offer a cabin filter kit but it only applied/applies to the F-150, Expedition and Navigator. Seems as though both a company know as "Cab Fresh" and Wix offer conversion kits but I cant find part #'s or any real info on either.
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Hotshot
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From: St Louis
If the heater core was gunked up, he'd get regular airflow when the heater control was set to "cool" as this setting bypasses the heater core.
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From: Suffolk, VA
Right, he stated that the airflow was the same in a/c or heat so maybe both are plugged up? Since there isn't a cabin air filter is it possible that dirt and debris might be in both the heater core and the evaporator?
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Yeah no obstructions anywhere. I'll be ripping into these later on this week. I'll be sure to post up with the results.
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I didn't want to just assume everything was as I thought it would might be and thats a big part of the reason I posted up.
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Tore into this today. Found two AA batteries and a set of keys sitting on top of the door that directs air to the defrost vents, keeping it from opening beyond a slit. Also the evaporator was almost completely clogged with dirt. Looks like we'll be conversing with our drivers about keeping **** off the dash and using recirc all the time when on dusty roads (thought that might have been a given).
Thanks to all who chimed in.
Thanks to all who chimed in.