AC Compressor fan - air flow direction?

[ajbell]

Hi All

Sorry if I get the technical terms wrong but I have an Air Conditioning problem - and this is a long read

I have 2 AC systems - one for downstairs and an identical unit for the upstairs.
Both compressor units are identical and sit at the side of my house.

a few days ago the compressor fan for the downstairs stopped running, the other unit
for the upstairs circuit is working OK.

I watched various online videos and I managed to get the fan to start spinning again if
I spin it manually - so I believe this means I have a capacitor problem?

For some reason I could not get the fan to spin while it was sitting horizontally in its normal
position within the cooling fin housing. I had to lift the fan out and tilt it back by 90degs to get it going and then
slowly (and carefully) lower it back into position whilst avoiding hitting the cooling fins.

I thought I was a real AC hero till I noticed 2 things:

1. The fan now seems to be running much slower than the fan in the identical unit I have for the upstairs circuit.

2. The air flow in the downstairs unit is sucking the air in from the top and pushing it out through the cooling fins whilst the other unit (for upstairs) is sucking air in through the fins and blowing the air out the top of the unit - I believe this is the correct air flow - in the sides and out the top?

The fan motors are both spinning the same direction - clockwise and the fans look to be identical.

The only difference I could see between the two units was that the upstairs unit (the one working OK) had a newer fan motor and the fan was mounted further up the motor shaft (i.e. closer to the motor).

So I adjusted the position of the fan blade of the downstairs unit to make it identical to the upstairs unit - no difference in the air flow direction - it still sucks through the top of the unit.

As a last resort I took the fan off and flipped it over to mount it "upside down".
I am sure it is now on wrong as the collar with the locking screw is now on the motor side and all the images I have seen on the internet show the locking screw collar below the fan.

BUT the air flow is now in the same direction as my other unit!

Am I going mad or can someone help me understand this?

Ultimately I know I need a new unit - I just want to limp along for a few months if possible.

I have to confess that everything was working OK till I decided to clean both units

 

[Stuff]

So did you or did you not replace the capacitor? Some motors will run backwards if you start them that way - look for an arrow on the label pointing or a CW/CCW designation.

 

[Sponsor]

 

[ajbell]

So did you or did you not replace the capacitor? Some motors will run backwards if you start them that way - look for an arrow on the label pointing or a CW/CCW designation.

I did not replace the capacitor.

But you may be correct in the direction.

The fan was definitely sucking in the top.
THEN after I flipped the blade over it starting blowing out the top.
BUT then it stopped again and when I started it it returned to sucking in the top .
But the motor appears to be spinning the correct direction - but it can't be?

Could the motor change direction somehow?

 

[ajbell]

UPDATE:
I replaced the capacitor - ALL is working again and air flowing in the correct direction

 

[Stuff]

Great news. Simple fix and the world is not upside down.

 

[Fitter30]

If the fan motor goes bad and if you go with a generic motor have to go by motor name plate amps not hp. If old motor is 1/4 hp and draws 3.1 amps and a new motor same hp draws 3.0 step up to a 1/3 hp motor. Unit manufacturers play with hp ratings on fan motors.

 

[ajbell]

my fan motor did go bad several weeks after the capacitor "fix"
I got a new motor today and got the fan running today but I don't think my system is cooling the house like it usually does.
I will post a new thread to ask questions about the blower motor.

 

[Fitter30]

With the hub set screw facing towards the end of the shaft. If you were to set the blade on a flat surface hub up the blade touching the flat surface is the leading edge thats the rotation.