A.C. Fan runs slowly

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rider1520

rider1520

Well-known member
Joined
Mar 15, 2010
Posts
258
Location
Nazareth, Pa
I have a 30 amp class A. I installed a second A.C> Domedic Brisk Air 2. It is separate from the 30 amp coacc. I installed a separate 20 amp circuit break box and inlet plug. Electrically everything checks out but when I turn on the A.C> the compressor turns on and draws 17amps but the fan only runs on the high speed and then only slowly ( like low speed). ANy ideas
 
What gauge wiring did you use? What gauge extension cord are you using to feed the inlet plug?
 
12/2 wire for the A.C. 12/3 for the extension cord. The wire run is about 26' the extension cord is 25'. The ground wire is also 12 gauge braided.
 
Well, that blew my theory. Can you safely take voltage readings when it tries to start and is running? It sounds like a low voltage situation to me. Maybe the feed to the extension cord is weak?
 
Is the fan mechanically bound up?  You'll have to remove the top shroud (outside) and spin the fan by hand to make sure it turns freely.  That's also where the run capacitor is located in case that's the problem.
 
The fan does not appear to be bound up but I have not taken off the shroud to physically move it. One thing we are going to double check today is the grounding. While we did get a reading (continuity test) when we tested for it, is there such a thing as an inadequate ground? We are currently grounded to the sheet metal wall of one of the outside compartments. Since a bad ground can produce the symptoms we have, we are going to move the ground wire to a frame member and then not only check the continuity again but also the voltage all along the connections up to and including the wiring to the A.C.
 
The only thing the ground does is provide safety against shock if an electrical defect energizes the case.  The air conditioner will run perfectly fine with or without a ground.

Since the compressor starts and runs, it's safe to assume the air conditioner is getting enough voltage to run the fan motor.

This sounds more like a defective fan motor or a wiring problem between the fan speed switch and the motor.  Does the air conditioner have the controls on the interior shroud or does it have a wall mounted thermostat?

If it uses the wall mounted thermostat, are the RJ45 connectors on the control cable installed in opposite directions as shown in Figure 4 of the installation manual?

Brisk Air Installation Manual.pdf
 
We finally figured out the problem, after double checking the wiring again we went to the roof and removed the shroud and found that the hamster wheel was binding against the styrofoam shroud! Lou you hit the nail on the head! We had to remove almost 1/4" of foam to finally get the wheel to spin completely free. After that everything worked as it should....thanks to all for providing your thoughts on a cause!
 
Congratulations!  Are you sure the hamster wheel is in the right place on the shaft, that it didn't come loose and move towards the styrofoam?

Usually there's an allen head set screw on the wheel's hub holding it in place ... you reach it through the opening in the middle of the wheel.
 
The wheel was just about at the end of the shaft (1/16th" from the end maybe) the shaft has about that same amount of back/forth movement but even moving the wheel & shaft as far forward as possible it still rubbed. Now that I removed some of the styrofoam it moves freely and works GREAT!
 
Lou...one question, should the shaft have some back & forth movement? It isn't much like I said maybe 1/16" but it does move.
 
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