A/C won't work. Need Help.

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Oct 5, 2010 | 02:37 PM

darrell_1000

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A/C won't work. Need Help.

The a/c in my 05 F-150 supercrew will not turn on at all. There is a buzzing sound coming from the fuse box that is over by the passenger door. Well, I traced it and it is the blower motor relay that is buzzing. Does anyone have an idea of what might be going on? Thanks.

Oct 5, 2010 | 04:22 PM

darrell_1000

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Anyone????

Oct 5, 2010 | 06:21 PM

Coskid

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I would start with replacing the relay it sounds like its gone. A buzzing sound coming from that would lead me to believe it is getting the signal but then can't send it back out.

Oct 5, 2010 | 08:41 PM

darrell_1000

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I replaced it today and still nothing. The a/c will not even turn on at all. None of the controls are working. Do you think it could be the blower motor resistor?

Oct 6, 2010 | 07:16 AM

TallEddie1981

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From: Fredericksburg, VA

The blower motor resistor only affects the blower motor, it doesn't have anything to do with the A/C kicking on. Usually when the resistor goes bad the blower will only work on the off and highest speed settings, you lose the in-between variable speeds.

Does the fan blow hot air when the heat is on?

First thing I would check is if the compressor is kicking on when you turn on the A/C. Multiple things could cause the compressor not to kick on; signal not getting to the compressor, bad clutch, low on refrigerant.

Oct 6, 2010 | 09:49 AM

darrell_1000

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Well, the heat will not come on either. Absolutely nothing works. It is strange because this just happened out of the blue. I have never had problems with the a/c or heat.

Oct 6, 2010 | 10:06 AM

TallEddie1981

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So it sounds like the blower is not working at all, correct? No air blows our of the vents on any of the fan speed settings?

Do you have auto or manual controls?

Usually when the resistor fails the fan will still work on 4.

Here is a thread on another forum that shows the location of the blower motor resistor.

http://www.f150online.com/forums/art...emtc-hvac.html

Usually that fail in the open position, that that is why the fan still works on the highest speed, but not the other speeds. Rarely the fail in the closed position and the fan will not work at all, so that could be your problem.

Check and make sure all the fuses are good.

I would open the glove box as shown in the link above and trace the wires to the blower motor and get a voltmeter and test for voltage at the blower motor resistor and the blower motor. And see if power is getting to either one of these.

You can also try hitting the blower motor and see if it kicks on. I just replaced a blower motor in a Chrysler town and country that would stop working but if you hit it, then it would work again.

I am pretty sure there is an electrical problem somewhere, power is not getting to the motor.