I just installed a new pollen filter in my '04 JTD and the air flow from the vents seems to be half of what it was. But if I'm using the fan and switch to recirculating the interior air (rather than drawing in exterior air) the flow is fine. Any ideas?

Recirculating is bypassing the pollen filter, hence full air flow from vents. Reduced flow on normal ventilation suggests the pollen filter is obstructed. I suggest possibilities are filter installed wrong way round, dodgy pattern filter, filter crumpled or distorted when being installed, foreign object has got in at installation or pollen filter cover not properly fitted.

Thanks, doctorchris. I'll pull the filter and check it again. What is a "pattern filter"? If it's a non-OEM filter, I bought the new one from the Fiat dealer, so I hope it's correct.

PandaEs said:

Thanks, doctorchris. I'll pull the filter and check it again. What is a "pattern filter"? If it's a non-OEM filter, I bought the new one from the Fiat dealer, so I hope it's correct.

Click to expand...

as I understand it, 'pattern' parts are non-OEM and not always a good fit, e.g. pattern panels such as wings have to be trimmed down to fit correctly...