Condenser fan acting weird

[mjpogue]

I have a 1 year old condenser (w/ heat pump) that just started acting funny. Sometimes the fan will run sporadically and make an arching sound (i believe this to be the fan motor engaging). However, this only occurs half of the time when it otherwise works just fine. I recently replaced the contactor, and I confirmed that it is engaging properly and the capacitor does not show any signs of swelling. What gives????

 

[glennjanie]

Welcome MJPouge:
The heat pump condenser is not required full time in the heating mode. It is discharging cold to the condenser coil (which has really become the evaporator coil) and collecting heat to bring in the house.
Quite often the condenser unit may ice up, which brings its efficiency to almost zero. Some units have resistance electric defrosters that kick on while others use a blast of hot gasses to defrost it. This hot gas defrost will sound like the unit is discharging, it gives off a big spewing sound very quickly.
If neither of my diagnosees appear to be working and the problem persists, come back and we will try again.
Glenn

 

[mjpogue]

Thanks for the reply. I have been watching over the past day. I do not get the excessive gas discharge sound or have any icing up. Do you think it could be either an electric or some type of valve issue. What would cause the fan to rapidly turn on and off?

 

[user 4883]

Current to the contactor coil is what's turning the fan on. I guess you could work backwards from there?

 

[glennjanie]

Hello MJPouge:
The condenser unit will have an access cover with the wiring diagram and often a 'ladder' diagram also. These two drawings will show you where the power has to go to get to the seperate actions and studying them will give you an indication of where the problem is. If you follow the ladder and test each item in order, you can usually find the problem.
Glenn