Front vents are not blowing air

CARL75

MEMBER
2000 MERCURY MOUNTAINEER
5.0L
V8
4WD
AUTOMATIC
215,000 MILES

Just recently I noticed that my front vents have stopped blowing any air. I can't use the defrost, A/C or heat. The digital control still works and if I have the A/C turned on I can feel a little bit of air coming from the vents while driving, but that stops when I brake. The odd thing is that my rear vents work just fine, on low, medium or high. They also blow hot or cold air depending on how I have the temperature set on the front control unit. I don't know what the problem could be.

Tuesday, March 12th, 2019 AT 11:23 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

I suspect this is a blower motor issue. I was thinking this could be an air door issue but if you are not getting air out of any vent then that is normally a blower motor.

Here is a guide that talks about this issue:

https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

The fact that your rear is working fits with this because you have a separate blower motor in the rear. So if the front is the only one affected then we need to start with this.

When you are not getting air coming out, let's go to the blower motor and check the voltage on the fan when it is on high. If it is 12 volts then the fan motor is the issue.

If it is not then we need to go back in the system to find out what the voltage is at the relay and then the resistor which is on the ground side and called the speed controller on the wiring diagram below.

https://www.2carpros.com/articles/how-to-check-wiring

Please run through this and let us know what you find and we can go from there.

Thanks

Images (Click to make bigger)