2003 4.4i HVAC airflow ceases after 1 hour.

[bassoprofundo]

After driving for an hour or 2, air flow from all vents will cease. Manual manipulation of the blower speed results in an audio response from the blower that tracks but no change in air flow. After parking (off) for an hour or so, system will return to normal operation.

While malfunctioning (1) Airflow from rear vents not affected. (2) Selecting MAX causes maximum blower sound but still severely restricted air flow.

Anyone experienced the same ?

[andrewwynn]

Sounds like your evaporator is frozen. The usual cause is slightly to little charge of "freon". When the charge is a little low it increases the pressure differential and then the temperature differential (Boyle's law I think). It will make the evaporator colder than 0c and the condensate will freeze solid and block the airflow. (this will happen on your house AC as well if the compressor contacts weld shut and the compressor never shuts off)

[bassoprofundo]

Thanks Andrew. I'll make that the first problem to rule out. makes total sense.

[bmw540san]

Originally Posted by bassoprofundo

Thanks Andrew. I'll make that the first problem to rule out. makes total sense.

Andrew is right. I had the very same symptoms this summer and no issues now in Winter which proves his theory. I'll recharge mine this next summer.