AC Electrical Problem

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wynn4578

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Oct 16, 2015
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Hello All,

Last night we had some pretty good storms roll through. During those storms, lightening struck somewhere near our travel trailer (possibly the powerline for shore power) and the power went out. It was powerful enough that it tripped a 200 amp main breaker on the pole and the 30 amp breaker for the travel trailer. We checked everything out and turned the power back on only to find that the surge had killed pretty much anything plugged in with a circuit board in it (tv etc.) One of the things it took out was the thermostat for the heat/AC units. I replaced the thermostat and everything works now except the condenser fan for the AC. I tested the line and found that I get power all the way past the control board (relays and everything seem to be working like they should) but still nothing at the fan, not even a hum. Is there another board somewhere between the control board and the fan or is it possible that my condenser fan was killed in the surge?

Thanks in advance,
Mark
 
Look for an inline fuse. It could be a "fuse wire". They look like a wire patch that has been added.

Could also be the starting capacitors.
 
Caps are my #1 suspect as well but let me ask

You said the relays appear to be working, do my mean you actually hear them CLICK or have measured voltage on the MOTOR side of the relay?  If so the caps move to the very top of the list.

And.. though it can not protect you in the event of a direct strike... Sometimes the MOV's will clip spikes from a near miss.. Consider a HW 30 or 50 (Depending on the RV) C from Progressive Dynamics.. I can not guarantee it would have saved your day.. but for sure it would not have hurt.  and on 30 amp RV's (or 50's with an adapter) Plugged into the "30 amp outlet" in a buddy's garage.. It can save you way more than it costs.
 
Hello John,

I can hear the relays on the control board clicking and I get readings on the output side of the relays. I had a surge protector (cheap one don't know the brand off hand) it fried that as well.

What are caps and how would I check them? are these replaceable? Thanks for the help everyone I sincerely appreciate it.
 
John From Detroit said:
Caps are my #1 suspect as well but let me ask

You said the relays appear to be working, do my mean you actually hear them CLICK or have measured voltage on the MOTOR side of the relay?  If so the caps move to the very top of the list.

And.. though it can not protect you in the event of a direct strike... Sometimes the MOV's will clip spikes from a near miss.. Consider a HW 30 or 50 (Depending on the RV) C from Progressive Dynamics.. I can not guarantee it would have saved your day.. but for sure it would not have hurt.  and on 30 amp RV's (or 50's with an adapter) Plugged into the "30 amp outlet" in a buddy's garage.. It can save you way more than it costs.
Click to expand...

I can hear the relays clicking and I tested them on the motor side. I get reading through the relays when they energized. By caps - are you refering to capacitors? Can you give me a heads up on where to find and how to check the capacitors. My electrical knowledge is limited and self taught.

I probably should have mentioned in my op that the compressor kicks on just not the fan.
 
One nickname of a Capicator is a "Can" because they are metal cans, with wires attached to one end, they will be "Topside" Up inside the roof unit) may be exposed when you pull the cover or may be in a plastic box.. The Cap will vary in size and shape but if you go to the SUpermarket and look at the Crystal Light powedered drink.. that's about the size of at least one brand Capacitor.. another is more round (think the same container round)
The Link (Wal*mart) shows three parts. 2 wires and a capicitor.. One I may wish to buy cause the Advernt air unit on my RV for sure is not a soft starter.. That puppy is HARD start (dims the lights or rather would if they were not 12 volt)
Advent Air RV Hard Start Kit
 
Capacitors may look something like these, they are from mine that blew out a couple of weeks ago. These replacements were $6 each shipped from Ca. and they replaced ones that were round like a orange juice concentrate can.

One way to determine if it is the cap that is bad, is if possible spin the fan on start-up, if it runs when you do that then the cap is usually bad. Replacements do not have to be the exact rating, but 10% over is allowable and I have gone much more than that without a problem. Look for the volts and MFD rating sometimes a symbol uf is used instead of MFD

Yours may be located on the fan or in a control panel, mine have been relocated here for ease of replacement so dont look for yours when you see mine.
 

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I forgot to mention another thing I did was to disconnect the wiring from the controls and using the wiring diagram wired a cord directly to the fan motor so as to eliminate all the controls from being the problem, and temporarily swapped capacitors from the evaporator fan. Just a process of elimination.
 
Thanks for the replies. I won't be able to check them out until Friday when I get back home but I'll post my findings and let everyone know.
 
OK, I have the fan problem solved. I borrowed a buddies meter that would read farats and checked the caps. They both tested good. Turns out I'm an idiot and tested the relay looking for 12v when the output should have been 120 ac. Don't know why I received a 12v reading (coincidence?) anyway the relay WAS bad. I relpaced it with a SS relay that I had on hand and now the fan works like it should.

I seem to have another problem though. When I disconnect the fan and turn the AC on I can hear the compressor? humming but it doesn't seem to be getting cold. No clue where to even begin on this one.
 
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