Hello,
Ive been reading the posts trying to see if i can do this myself but i am stumped. about two weeks ago my ac outside unit stopped coming on, checked the circuits and the AC circuit breaker was off. so I flicked it on and it quickly kicked back off. Never worked on an circuit breaker before and figured something else was wrong with ac, I called a service tech. they came out, replaced the circuit and the system kicked on. they left. About an hour later , the house was not cooling much and checked the breaker, it was fine, went out back and the fan was not on. called the techs and they said that freon looked good etc, would be another service call etc. I decided to start reading. we had some nice weather for a few days so i had some breathing room, but as it warmed up, I turned on the ac and it worked perfectly for ~1.5 weeks. One of the suggestions i had read about was to change the capacitor, so i did change it with an exact one and problem still continues.
The problem is when I turn the Unit on via the thermostat, the outside fan kicks on and works correctly, once it reaches temp, it shuts off, but when the house warms up and it restarts, only the inside unit kicks on , the outside fan wont...i can hear the compressor humming, but the fan wont turn. the compressor hums for about ~7-10 seconds and shuts off. I then go to the thermostat and shut it off, wait a while ~ 5mins and then on and it works ok. i've been doing this now for a some days and i am no closer to figuring out what is happening and why.
could it be the fan? it does work ok, but when it runs for say 8-10 mins, it will shut off, way before the house has reached the set temperature, and then only the internal one is running. i go and shut off thermostat, wait a while and turn it on and back in business.
sometimes i turn on the thermostat, house will read 80, i have it at 78 and nothing happens for ~2-3 minutes, then it kicks on and fan starts and works ok. on those instances when it doesn't , i have gone outside and started the fan with a stick and runs ok once i do that. this doesnt happen all the time, but seems to do so about 1 out of 10 times.
any help is appreciated, i am willing to try anything to do it myself, but just not sure what the next step is etc.. thanks for any help provided.

 

These intermittents are always difficult to troubleshoot. I would suggest trying to replace the contactor. The contactor is a relay which controls the power to the outside unit. When the thermostat calls for cooling, it sends 24VAC to the contactor coil which pulls down the contacts, closing the circuit and sending 240VAC to the compressor and condenser fan.

My thinking is that the contactor may have some burned contacts that have high resistance causing a voltage drop across the contacts. This would result in low voltage to the compressor and condenser fan, causing hard or no starting. Contactors are very inexpensive, so it's worthwhile trying it.

 

BoB14525- thank you sir, i've been reading about the contactor as well and thought that may be my next best bet. when i replaced the capacitor, i looked at it, but honestly i didnt see anything wrong, at least to the naked eye or untrained eye. anyway, thanks for the input, that does seem like a inexpensive next step. One thing to mention, as i type this reply, I sit in the room/window right next to the unit, so i can hear it running and when goes off, i go and turn off thermostat etc. today its really warm and i have noticed more than a few times that the house is not reaching the temp its set at, but what I am hearing is the fan cutting out say 5 or so minutes into the cycle and then nothing, the internal fan keeps blowing etc. i go and turn off and repeat. but what I am hearing is like the fan is making a different sound after a while, not bad(i guess) just a not normal sound, almost like a out of sync humming and then its when it shuts off...would that still be the contactor issue or points to something else possibly...fan? that only seems to happen when its really warm and the fan cant seem to stay on long enough on cycle to cool off....

btw thanks for your input/reply, its much appreciated.

 

One other thought. Have you checked the electrical contacts on the compressor? With the power turned off at the electrical disconnect near the outside unit, check the condition of the wires (normally 3 wires) where they attach to the compressor. If one or more have developed some resistance due to corrosion, the wire will overheat and can actually burn up. If the contacts/wires look questionable, clean or replace the terminals and possibly the wires if they look burned.

I'm thinking back to your original comment that the compressor hums for 7-8 seconds and then shuts down. This leads me to think it's an electrical problem (low voltage).

 

Bob14525- no i haven't done that , at least not with any intent, i really only looked at things the day i changed the capacitor, but i will check again. right now the sun has gone down and it seems to be running longer and without shutting off and or it runs until the set temperature is reached and then shuts off.
I guess my question, and forgive me for the repetitiveness, is why would it kick on when i first set the thermostat on etc, but once it initially shuts off(reaches temp) it wont function the second go round unless i turn off thermostat (wait a while) etc. i guess my brain thinks this is the connect with my issue, but since i know next to nothing, I appreciate your advice greatly whether it fixes or not...I am learning a lot more than i thought, so thanks again.

 

Welcome to the forums.

Time to change the fan motor.

 

PJmax- thanks- I think along those lines as well, but i read somewhere that if i can start the fan when it engages with a stick(fan spins freely) then most likely not fan and possibly capacitor. so i changed capacitor and stil problem remains, but I am not disagreeing with you as every so often, the longer it runs, the fan begins to make a pitch type sound off and on...so maybe something is going on in there...well i guess that could be another or the whole issue...thanks, will have to keep that in mind and see what if anything gets done with contactor replacement , appreciate the input

 

As the fan runs it gets hot. The bearings got very hot. The motor stops. When it's needed to restart the bearings are still hot and the motor cannot overcome the friction. After the motor cools down the bearings are cool and the motor will run again.

Usually if the fan is running any length of time it will start to growl and possibly start to slow down.

 

PJmax- thanks- that does fit in with my scenario and like i mentioned , i do hear some odd type pitch coming from the fan when running a while etc...and yes, the longer i leave it off the more certain it is to fire up again as opposed to turning it on in x amount of minutes and just hearing the compressor. Well, thanks, I didnt read up about fan changes, so guess thats my next to-do as its getting warmer here by the day etc. - any good tips on changing out the fan?

 

If you post the model number off the condensor I can point you in the right direction.

 

PJmax-
is this the information that you are referring too? pic attached

 

Carrier 38EZG048300

There are several numbers that will work there. This is the most popular...HC39GE237

amazon/Emerson-HC39GE237/dp/B00401CLJI
repair clinicl/Carrier-AC-Condenser-Fan-Motor/HC39GE237

It appears that HC39GE226A may also be a replacement. You'd need to check with selling dealer to verify.

HC39GE226A - Carrier GE / Genteq Replacement Fan Motor 1/4 HP 208-230 Volt: Amazon

Be sure to order with a new capacitor. The cap. must match the spec on the motor.

 

PJmax- thank you, thank you...and from everything I've been reading, it doesn't seem too terrible difficult to do the install, so a lot of savings there and learning on my part.
I had replaced the capacitor last week as that seemed to be a common issue that was highly recommended as a first step etc, so it has a new one with the same 50/5 fu and voltage. I will get this going and see how things turn out but either way thank you for all your help and following up on my problem, surely there are many out there, but its great to get help during this time.Ggod bless you and take care.