Recirculate Door 'Fix' No Good

[Ifixyawata]

When I bought the '04 Mountaineer in my sig I noticed right away that the air flow from any and all vents was very weak. Reading on another forum I found that the most common problem is a fallen recirculate door. Sure enough, after tearing into the dash (via removing the glove box) I found that the recirculate door, which selects either inside or outside air as the source for the blower fan, had fallen down and landed flat on top of the blower inlet, this, restricting most all air from the vents.

The proposed fix, much heralded and praised, was to simply remove the door altogether. Some went even further and sealed up the outside air inlet under the cowl; thus putting the vehicle in recirculate mode ALL THE TIME. Something didn't sit right with me regarding that approach. Mainly the fact that most vehicles FORCE the box out of recirculate mode when Defrost mode is selected. Sure enough, once the wet and rainy season came, the inside windows were never quite defrosted well enough. As if I needed more proof, riding shotgun in the cold winter time proved that once the inside and outside air intakes were opened up (and connected to one other, also) the passenger's seat got drafty.

Am I right in thinking that the lack of a recirculate/fresh air door is causing the sub-par performance of the defroster?

The 'right' way to fix this 'fix' would be to pull the dash out away from the firewall and partially dis-assemble the box, etc. Weather being what it is right now, I think I'd rather try to cover up the inside air inlet, forcing the car to only pull in fresh air at all times. Is this a reasonable fix? I have some gaff tape (think duct tape but doesn't leave residue) that would fit the bill, assuming I can get in there and cover the recirculate inlet. I need to find a solution as we had a very wet weekend and all the condensation that was inside the windshield turned to ICE and tonight I had to scrape both sides of the windshield.

 

[Johnny2Bad]

Sounds good to me. I could never figure out what the point of the recirculate mode was in the first place. Every vehicle I own is permanently set to outside air.

 

[Ifixyawata]

I think the idea behind it is to get the A/C (remember MAX A/C on older cars?) as cold as possible during the hot summer. I find that it has minimal effect besides making the fan louder by opening up the inside inlet.

I guess it could also be used to prevent unpleasant smells from coming in the car but once you can smell it, it's already in the car and thus too late.

 

[THafeez]

exactly what you mentioned. I have no idea why but if I have it set to outside air, I can smell fumes from diesel trucks etc... I have changed the cabin air filter about 5000 miles ago, but even when it was new those smells made their way in. Is outside air filtered? Maybe not in toyotas. Someone correct me if I am wrong please.

 

[Ifixyawata]

My focus is set up for cabin air filter and it filters the outside air only, it seems. I don't currently have a filter in there because I guess no one ever added one, just am empty 'mesh' box.

 

[B320i]

I always defog with outside air, using the heater controls. Owner's manuals frequently warn of using "recirculate," as the additional moisture from interior occupants could cause more fog, or the cabin air to become unfavourably stale. Some newer vehicles with rotary controls indicate "Use *FRESH AIR ONLY.*

Recirculate with A/C is nice for an extra boost - assuming the indoor temperature is already cooler than the fresh intake. Recirculating straight from a parked, hot car doesn't work well. Its also good in humid or rainy conditions where the A/C might be quite have enough 'oomph' to cool + dry adequately at a stand-still.

Despite its age, the analogue climate-control in my old Bimmer recirculates automatically when hotter than set temperature. I hear the movement of flaps in the HVAC unit and changes in air temperature and humidity of the air output as a result - particularly when recirc mode ceases.
This "feature" is inconvenient when cooling a very hot car. You're using roasting hot air from inside, trying to cool it, then circulating through roasting hot duct-work...

My suggestion would be to check for proper operation of the defrost, and trying cleaning the window. It could simply be "outgas fog" from the trim. Cycling of the A/C in defrost mode (if active) may also cause intermittent fogging of the windows, as can the glass being too cold relative to outdoors.

 

[KGMtech]

In Canada, and anywhere that you drive for 5 months with the windows sealed shut, the recirculate mode will - after a long drive make you feel drowsy.

I only ever use it when the car needs faster cooling or heating. I question the 'faster'

 

[asand1]

Defrost should circulate so that all the humidity can be removed via the AC condenser. If outside air was coming in it would always be damp.

 

[Ifixyawata]

Originally Posted By: asand1
Defrost should circulate so that all the humidity can be removed via the AC condenser. If outside air was coming in it would always be damp.


But, that's my point, defrost CANNOT recirculate due to the electronics/mechanics of the box. Doesn't the incoming air, whether it's inside or outside, pass through the condenser to get dried out either way? I see what you're saying but I think the moisture has more of a tendency to build up inside with wet shoes and therefor carpets, etc.

 

[B320i]

Originally Posted By: asand1
Defrost should circulate so that all the humidity can be removed via the AC condenser. If outside air was coming in it would always be damp.

All the 2000's Toyotas, Hyundais (and otherwise) I've seen explicitly note on the HVAC controls to ONLY use fresh-air when defogging/defrosting.

On some vehicles, selecting the Defog/Defrost function will start the A/C compressor. Air will always pass through the evaporator before the heater core (if it is blended in by the temperature control). The cycling of the A/C momentarily so as to avoid freezing up may cause small amounts of fog. But it will absolutely not inhibit normal operation.

I've not used re-circulation for defogging the main windscreen. Fresh air and heat has always worked perfectly.

 

[01rangerxl]

I'd cover the recirc inlet.

I am pretty sure both of my Rangers only recirculate when in the MAX A/C setting, which I almost never use if temps are below about 100*F. Except for a couple of times a year for maybe 15 minutes at a time, the HVAC is drawing mostly outside air, so I would leave that inlet open.