My A/C wont turn off!

[Big country]

Well I can switch between hot and cold on the climate control panel and it says the fan is going up and down when really it's still blowing full blast. Oh and when you turn the unit off the defroster stays on full blast. I don't get? The control panel seems to be working fine and changing things when it's supposed to, but it seems like something in the dash wont go off.

 

[Englishman]

I would start with with a power cycle (Disconnect either the heater control unit or the main battery) first. If that dont work, then individual controls or a sensor could be the problem. Depending on the newness of the car would dictate if you could do this (older model) or a need to go to a dealer if its a late model with a computer controlled everything !

Good luck !

 

[Big country]

It's an 03 Nissan Pathfinder it's got computer everything.

 

[MadMo44Mag]

BCM
Body Control Unit
I have seen this before and the BCM is the usual culprit

 

[Big country]

Okay were would I find that on my vehicle and how expensive is the part and how much of a PITA is it to put in?

 

[fuelfather]

under the dash, or hood.

 

[Freedom1911]

Pull the fuse.

 

[M. Sage]

I'm not sure a Pathfinder's AC controls go through the BCM. Usually if the fan goes full bore all the time, it's a bad blower resistor. Are all the "on" positions giving you full blast? Does it turn off?

 

[Sigman44]

Sage is correct. Now if you want diagrams and test proceedures let me know.

 

[Big country]

I'm not sure a Pathfinder's AC controls go through the BCM. Usually if the fan goes full bore all the time, it's a bad blower resistor. Are all the "on" positions giving you full blast? Does it turn off?

Well the when the control panel is in the on position it's going full blast whether the little fan symbol has one fan blade lit up or all four. And when you turn the unit off it sounds like it's blowing full blast threw the defrost vents but after the ride home yesterday it might be the floor. But it sounds like it's not turning off like it did before.

 

[Freedom1911]

Well... it was a thought any way.

 

[Big country]

Hey thanks for the thought. It's a hell of a lot more than I had before.

 

[M. Sage]

Yeah, I'm really thinking blower resistor.

 

[Big country]

Alright Is that a plug-in part so to speak or is it a little more complicated than that? And is that something that the guys at O' Reilly's can plug their tester in and test for the problem?

 

[Major Woody]

I'm thinking speed resistors too. Could be part of the switch, or on a circuit board.

 

[TexMex247]

It's just as likely a stuck(on) relay. Most resistors can only reduce the blower speed and full speed usually bypasses the resistor and applies full voltage and therefore full speed to the blower motor. Knowing that is not a mechanical type control face makes it just as likely a canidate as a stuck relay. If I had a wiring diagram,I could probably look at it and tell you which one it is.

 

[Big country]

It seems like it's a relay and it's under/behind my glove box. (OH FUN!) I'll get around to it soon I hope it's annoying.

 

[M. Sage]

I just looked on a repair info source here at work. It's got a tech line section where you can find common issues. I'm going to give this a 90% odds that it's the "blower motor amplifier", which is what takes the place of a blower motor resistor on these. It's behind your glove box (take the glove box out) just to the left of the blower motor itself, and screwed to the HVAC assembly with two screws.

 

[Big country]

That's what an illustration on line said but the only problem I have know is 1) I have not figured out how to get the glove box off, and 2) is the rain stopping long enough to work on it. LOL Thanks for the help Senior Sage and every one one else.

 

[M. Sage]

It's not that hard, most of the time they're attached on the bottom. Sometimes you can just pop the box open past the stops.