Electricians: How can i test compressor fan on ac unit?

Aww man you sound like me. Loosen up the wallet and pay a guy that knows just what the hell he's doing. I've spun my wheels too many times.

Lol... I can't, I can't.

The outdoor central air unit only has a few functioning parts. I've narrowed it down. If I test the fan and its fine then I'll call the repairman.

Wonder where that myth about men never stopping for directions comes from, eh?

I have no idea what I'm talking about but... wouldn't you just apply power directly to the fan and see if the spiny part moves?

Yup, bobo. I'm just wondering the best way to apply said power. The compressor fan doesn't have a plug, but I'd think I could strip the wires and hook it to a normal plug... maybe? This is what I'm wondering.

If I can rewire a 600w HPS light for growing "tomatoes", then surely I can do the work to test this fan.

If you'll set me up with some "tomatoes" I'll fix that damn fan.

I would think the fan is connected to the controller with either a blade connector or a closed end connector.

Regardless, cut the power to the unit before do anything.

You could also call Fry's. They do good work for me.

If I don't figure it out, then I'll certainly offer a couple ounces of "tomatoes" in return for fixing.

Luckily, I'm deathly afraid of electrocution, so I always but the power first.

1. I am not an electrician, but I have worked on my own air conditioning units many times in the past.

2. There are many parts that can go bad that cause the fan not to run. For example, you might have a bad switch, or a sensor, or a component with cicuitry, or (if a newer unit) a compterized control panel.

3. The quickest way to test is to use an multimeter. These can be purchased at any hardware store, and they range from the cheap (%15-$20) to the expensive ($100 or more) depending on the features and the quality of the device. An A/C will come with an instruction manual, but the device is fairly simple.

4. Now the tough question: if you do not know what you are doing, why are you wasting time? You might injure or kill yourself, and you might make the problem worse. If this was a $15 box fan from Target that you wanted to screw around with, I can see where this might be tempting, but A/C units are expensive. I learned how to perform basic A/C maintenance and fairly simple repairs out of necessity (I owned businesses with creaky old A/C units and got tired of spending $1000 or more a month in the summer) but a homeowner with little to no A/C experience is wasting time and money - and increasing risk of harm - by trying to be a Johnny-Fix-Everything-Myself. Hell, these days I don't even change my own oil any more, since I can get a trained mechanic to do it quickly and cheaply. Oh, and I do not waste my time screwing around with A/C units, either: I figure my time is worth at least $30 an hour, and if I wasted 6-8 hours on a repair I may or may not be able to fix, that is waaaaay more than a service call.

5. Take a deep breath and get a reputable A/C technician to take care of this: it will be done in one-tenth the time, it will be done properly, and you will be cool in a matter of hours. Hell, with the 105 heat index today, the last thing I would want to be doing is messing around a shiny metal box in the hot sun.

this happened to me before. when i called my guy he had me take out the battery unit (or whatever that is called) in the box (with everything off of course) and put it back in after awhile. fired right up after that.

first minute and half of this video is OK at troubleshooting a 240 volt single speed motor
http://www.youtube.com/watch?v=1bDThRugxX0&feature=related

this video deals with a multi speed fan motor and gives you a bit of Electricity 101
http://www.youtube.com/watch?v=yqiHh_Rufi0

Disclaimer: If you dont feel comfortable having live power on (240 Volts) while troubleshooting call in a professional, and please disregard the first video link

Please stay away from the "tomatoes" when working with electricity.
The one time my a/c went out was when the capacitor was bad. It did not look any different than when it did while working. That may be your problem and testing everything else will only be time wasted.

There re 2 motors in there, the compressor and the fan, both I believe are 240 volt. IT could be a bad relay, I've seen bugs crawl in there and stop it from making contact. Or the capacitor is bad. Chances are there isn't too much in the way of complex circuitry in there, your furnace might have a circuit board but doubt the ac condenser unit outside has one. It's not a complex operation, it either runs or it doesn't. If you check it with a multimeter set to ohms you should get high resistance but not off the scale and a low resistance is bad too. I'm not sure how you would check the capacitor but that alone will knock you on your butt if your not careful.

OK, I am getting the urge to play along now:

1. Does the motor hum for a moment and then go "click"? If so, it might need oil (if an older model) or it might need to be replaced/repaired.

2. Is the exterior of the motor assembly hot (if not in direct sun)? This might indicate that the motor overheats trying to kick in.

3. Agreed with Linecrosser that capacitors can look perfectly fine and still be fried.

4. I really urge you not to try to hook the motor up to an external A/C source to test it, even if it is 120 volts. This is a lot of extra work (removing it, rewiring it to add a power cord, etc.) and this can be deceptive: if another component in the circuit prior to the fan is bad, all you will have learned is that your fan still works. The multimeter will tell you that in 10 seconds (as will an experienced A/C tech).

5. And I assuming that you are talking about the condenser fan (the one outside with the compressor) and not the fan inside the house that blows the delicious cold air across your face as you enjoy an icy Heineken in your Barca-lounger?

Most outside units use the same contactor for both the compressor and cooling fan.If your compressor is running then I doubt that you have a bad contactor.If you can get access to the fan blade you should try and see how easy the blade turns.You should be able to spin it by hand and it should continue to spin for a few revolutions.If it turns hard or seems stiff then you can try and lubricate the(sleeve) bearings with a light oil.(3 in 1 oil)If it turns freely but yet you can hear it hummimg when it trys to start then I suspect a bad start capcitor.Some units also have thermo-discs in line with the motor leads.Sometimes they can go bad.It would be nice if you had a capcitor checker and a meggameter to check the windings of the motor.An ohmeter would also be nice to have if you can't get any of the other test meters.Do not try and hook this motor up to 120vac power because most of these motors are rated for 230vac single phase operation.Good luck.Be careful not to touch any live parts.

Thanks all.

After reading that I would need to have the electricity on to test the fan, I decided not to attempt. I don't fuck around with electricity. I put a 12v battery to my tongue as a kid, and that was enough. (perhaps it also explains more?)

Anyhow, I found out the neighbor's kid is an apprentice in the electrical trade. He showed me how to test the fan. Sure enough, the fan motor was toast. I bought the neighbor's kid a 24 pack of beer for his help, and he will be equally toasted -- hmmm... I hope he's 21...

I installed a new fan this evening and am enjoying.

Cheers and thanks.

"Electricity doesn't scare me JJ but do get a voltage meter to check for voltage going to the motor,"
you can also go to "youtube" or www.wonderhowto.com and it will show you video on the subject,just type in what yr looking for buddy, like on wonderhowto type in WEAPONS and it will tell ya how to make a hand held cross bow"!!

I have a test meter JJ if yr interested,can't drive to cuz my truck was totaled Friday am..

I'll watch the news for you. I'm putting together a poll on whether the underage drinking or electricution story gets top billing.