AC quits blowing - Ford Forums

jim56 · 06-29-2009, 09:29

Lately (it is really hot out), the A/C on my '03 Navigator will occasionally stop blowing from the vents, even though I can still hear the fan running. It does this every couple of minutes or so for about 30-60 seconds, then resumes normal operation. The rear vents arent affected.

**360ci** · 07-01-2009, 20:27

Sounds like a bad blower motor resistor. There's one for the front system and one for the rear.

**jwko** · 07-01-2009, 21:43

Quote:

Originally Posted by 360ci

Sounds like a bad blower motor resistor. There's one for the front system and one for the rear.

They say the can still hear the fan running. Sounds like something is blocking the airflow. Could possibly be the vent selector (floor, defrost & vent) mechanism under the dash.

**360ci** · 07-02-2009, 12:38

The blower motor resistor can burn out on any fan setting, and will generally not allow to change to another setting. I believe it's mostly caused by leaving the fan on, or having the A/C and fan on when you start the vehicle. I'm not certain of course, but my Dodge Durango is prone to having bad BMR, mostly in the front. I haven't had to change mine out, but one owner mentioned his fan was stuck on high, and none of the lower settings worked unless he turned it 'off'. Strange stuff. But yeah, the selector could also be the culprit :)

jim56 · 07-03-2009, 18:11

I can hear the fan still running. It acts like whatever controls where the air goes ( vents/ defrost/floor) is cycling for a minute

**360ci** · 07-04-2009, 06:35

Quote:

Originally Posted by jim56

I can hear the fan still running. It acts like whatever controls where the air goes ( vents/ defrost/floor) is cycling for a minute

That would be the blend door.

jim56 · 07-15-2009, 18:53

I have now determined that it happens when there is a load on the engine, as it going up a hill. As soon as I let off the gas, the air starts coming out of the vents again.

fixitnowlt · 07-15-2009, 19:18

You are loosing vacuum to the a/c head. Check the black vacuum hose going to the a/c head. It runs through the firewall to the engine. I think the line tees into another one in the engine bay. I'm not sure if these have a reservoir(been awhile) if it does, it may be cracked. The a/c head itself is a possibility as well.

FYI- (simply put) vacuum is lowered when the throttle is opened and comes back when it is closed.