technical question regarding condenser fan motors

[eclipsetim]

Hey my name is Tim.
To start with a fellow employee replaced a 3/4hp 220v TEFC condenser fan motor. This condenser is actually for a walk in freezer. It's horizontal mounted by belly band and the condenser has a fan shroud built on. The problem is the motor is over heating. This unit is suppose to **** air thru the condenser over the motor thereby cooling the motor. When I looked at the fan blade I noticed it is even with the outside edge of shroud. The air seems to only blow out the sides and seems to actually be causing a vacuum directly around the motor. The shell temp was 156 degrees Fahrenheit. Way to hot.!. So my question is where should the fan blade sit in the shroud for maximum air flow and proper cooling off the motor. I'm going back to the site monday to fix it.

So far I have read a half and half rules. Half in and half out. Can someone confirm this and explain the workings of said rule if so

 

[Mr. T]

I can't give you any direct knowledge but I can tell you what I would do in this situation. Call the manufacturer and ask to speak with an application engineer.

 

[eclipsetim]

This system is almost older then me. That is why I come here. These systems are custom built to owners needs. There are no nameplates or information

 

[FullRaceMerc]

So far I have read a half and half rules. Half in and half out. Can someone confirm this and explain the workings of said rule if so

This ^ is what I was taught & have always aimed for. I always thought it was the most efficient location for moving the most air thru the condenser/evaporator/radiator.

Does the motor have lube ports? Some of those have holes at the ends to add oil to the bearings & should be lubed periodically. How long has the motor been in service? Does the belly band block any cooling holes?

 

[Rookie2]

I would say half and half also. Is the motor turning the same direction as the old one ? I would think that the motor should push air through the condenser ? not sure though as residential pull hot air over the motor.

 

[Mr. T]

My apologies. I thought that when you said you replaced the motor that it was a new motor.

 

[zmaxmotorsports]

Is it running the right direction?

 

[A_Pmech]

The shell temp was 156 degrees Fahrenheit. Way to hot.!.

What makes you say it's too hot? If the air off the condenser is 38C that's only a 30C temperature rise.

Have you checked how much current it's drawing?

 

[pigsitter]

First thing I would do is make sure the motor is turning the right direction. If a universal replacement was used it's quite possible the rotation is reversed. Also check the blade as I recently ran a similar call where the previous tech had put the blade on upside down.

 

[slice]

If motor is overheating. Did you pull amp draw ?? That will tell u if motor or blade is issue

 

[eclipsetim]

Guy had been using a fan laid in front of condenser for a year. Directly replaced motor. Right direction. Fan still has direction sticker. Motor is rated at 4.7 amp. Pulling 4.2. Even tested with scrap paper to front of condenser. I know motor is hot because you can't touch it and I took temp of shell. And this is the second new motor in the box.blade is balanced. Motors four vent holes are unsealed as motor suggested. I've worked on these types of motors for four years. Only been installing for half a year. It's the first time I come across this. I suspect the original motor we found on it was incorrectly installed via the fan blade and we just went back to what it was. Motor will trip the thermal protector after hour or half hour prob. Belly band did not interfere

 

[eclipsetim]

Shell temp was 156f which I think was 67c