Fan Motor Running In Reverse | HVAC Service Call

At this service call the condenser fan motor is running backwards. There are a few possibilities as to why this is happening. Watch until the end to find out the solution! Thanks for watching!

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[dougfisher]

I found mine was running in reverse. Did some investigating. There's 8 wires coming out of the fan motor. 2 are the power leads, 2 are for a running capacitor, and 4 thinner gauge color coded wires connected with spade connectors to each other. Label on the fan motor has a color to color connection diagram for these 4 wires to select the rotational direction. So glad it was an easy fix. Thanks for the vid.

[tracysellman]

Good job as a 30+ year retired Master HVACR tech, your thought process was spot on. I am also glad you also called the motor and let the customer know it needs replacing those baring and windings in that motor are shot and sound like poo. I have seen tech's not tell the customer about this kind of problem, (maybe from lack of knowledge or just don't care but that dose not serve your profession or is in the best interest of the customer.) and have a call back, which kills you creditabilty in the customers eyes. On a condenser fan motor running backward for a long time kills the magnetic fields and destroys the windings and bearings from the added heat and harmonics. If you bench test that motor with an oisiliscope it will prove that fact. I know this is beond what would be expected of a technition. But beleive me it is true I have a friend that was a electrical engineer and we did just that test. Just an FYI, also all new techs should watch using reversible universal condenser fan motors for horse power, amp draw, and RPMs not to mention making sure the fan is running the right way. Nice job HVAC Tech Tips. PS: I have seen a run cap test good at say rated at 5.0 MFD and test at 5.9 MFD and the fan motor be good also but the fan would still run backwards from high winds. When the unit shuts down and the wind starts spinning the fan the wrong way it will continue to spin that way even when the unit comes on, as a younger tech this problem drove me nuts for about 2 days on a commercial roof top unit, until I cought it in the act. I had to install a high wind shroud on the top of the condensing unit to stop it.

[frankyb]

I’m a new tech and I have been following you for some time now. You have help me with a lot. Thank you for explaining the whys.

[PederRovelstad]

Thanks for the assist getting my 30 year old AC running again. Found the cap swollen on both ends. Replacement from Amazon the next day, cold air 20 minutes later. Thanks again!

[Heavy_metal_rulez]

nice video. another way the fan would run backwards is if you accidently put the motor lead on the herm side of the capacitor. learned that from doing a maintenance on a unit one time

[pollydor]

Good job and nice work . I’m retired graduated from LINCOLN TECH Columbia MD 1996 .

[popples]

Subbed❕
Excellent presentation, very informative. You're quite knowledgeable & your explanation is easy to comprehend.
I give you many thanks.

[nate]

When our company is ready to hire, we hope we find a tech as good as you. Good job!

[gregorynolan]

Good Job! Nice to listen to someone that knows what he is talking about

[robevans]

Wouldn't have expected that cap being the cause, as it tested out pretty near its rating. Just goes to show, though, that it's always worth substituting a known good capacitor before assuming the motor needs replacement (provided that the motor sounds and runs properly with the good capacitor).

[EverythingHVACR]

Nice job! interesting the cap reads good but still runs backwards. keep up the good work 💪

[desertweasel]

My fan is running backwards and I am waiting on the repairman now. I pray he is as competent as this guy in the video and not some landlord jackleg. This guy knows his stuff and actually has all the technical knowledge you need. I am an electrical foreman and i forgot my tester at work so I hope I see him doing this the right way with real equipment.

[charlesmartin]

As part of a Home Depot deal, an HVAC guy checked my system. The fan was running backwards. He said he tried switching the wires, and then the compressor would not turn on. He suggested a new AC unit. I saw this video and decided to try a new capacitor. I looked at the wiring diagram inside the cover, and it turns out the herm and common wires were switched! Now I have extra capacitors (dirt cheap), which I will keep for an emergency, and a motor which I have to return (at cost to me). He estimated $1800 to change the motor!

[MariosACandRefrigeration]

the red wire goes on the 4 spade terminal C, 7:22 somebody switched yellow and red that is why it ran backwards, but that is a great way to verify,
.thanks for sharing.

[juliomendez]

Just had this situation happen yesterday! I'm the only one working on the system therefore I went straight for the capacitor and found the capacitance was still good. Replaced the motor, problem solved!

[Eddy]

That's why I keep you around cause you can figure things out ... Good vid ... Thx man ...

[condor]

Excellent video - 4.5 microfarads on a 5 microfarads capacitor is off 10% which I have to believe is out of spec right? Great job diagnosing. Never seen or would have thought a bad capacitor could cause the motor to reverse!

[Retaile]

An ac motor will run in either direction depending on how the capacitor is wired, but a bad capacitor reversing its start direction is crazy. Electricity doesn't follow any logic when it comes to failure. Have you encountered any instances where compressor tried to reverse when a capacitor failure occurred? Great video!

[a.b.]

I have had capacitors check out good with a meter and yet when I changed out the capacitor, then the device worked correct. My best guess is the low voltage of the meter does not reflect the higher operating voltage when the capacitor is in the circuit.

[Trump]

Had this happen on a boat once! We were on shore power left for the weekend and an electrician came down and replaced a transformer on the pier. The electrician didn’t connect the phases back the same way. The air compressors air conditioners and everything with a three phase motor ran backwards. Most stuff was ok but the air compressors all locked up as the oil pumps don’t work when it’s turning backwards. The AC unit somehow survived running backwards for the weekend it sounded horrible when we arrived on Monday morning but after swapping a couple phases the thing quieted down eventually. The air compressors were junk. Fortunately we didn’t have most of the stuff on the boat running. We had to replace the AC compressors a few months later as they were severely damaged from running backwards for more then 48 hours!