-
OTRCondensor fan relay got hot and tripped breaker
Pulling at straws here! What would cause the OTR condenser fan relay to get hot and trip the breaker? Bad fan motor? How do I check the motor to see if it needs replacing other than direct connect to 24 volts? It’s either a bad motor or a bad connection. I have a questionable wire coming from my batteries hooked to 12 volt (+ positive) that goes to the breaker buss bar but in the Prevost battery break down it shows it connected to 12 volt – (negative). Any thoughts? Thanks!
-
11 Replies
-
Usually when a relay gets hot it is resistance across the contacts. But while than may contribute don’t rule out the breaker being weak and also in need of replacement. An old breaker may just trip due to increased current as a result of resistance across the relay contacts.
The only thing I would check on the motor, other than insuring all connections and bearings are good is the condition and length of the brushes. I am guessing but I think the Prevost limit for the brishes is 3/4″.
-
Thanks Jon! I will have the motor checked.
If the relay has a resistance could it be voltage related? I know that the relay has 27.5 volts at the fan power lugs. More than enough to power the fan motor. However, when it shut down yesterday the relay was so hot you could not touch it. I let it cool down overnight and found the tripped breaker the next morning. After resetting the breaker, evap fan and compressor clutch engages or comes on but not the condenser fan. Changed relay out still no condenser fan. I’ve had this questionable thought that the mechanic installed my batteries wrong a couple years ago. I went back and connected them as per the drawing and they have started the bus without problem. There were 2 wires I had a question about that were not connected like the drawing. One goes to the breaker buss bar in the battery compartment. I had always had it connected to 12 volt positive on battery A1 but in the drawing it shows it connected to Battery B1 12 volt negative. (I filled it in with red below) Apparently the mechanic could not remember either! Always cranked good but never tried running the OTR ac until this year. The other wire goes somewhere in the bus, I have no idea where. But it is connected to Battery A1 12 volt negative. Any thoughts? Thanks! MT
-
What you might consder “hot” might actually not be hot.
I suggest before you consider something an issue or part of the problem shoot some temps with your IR gun. To your fingers 115 appears hot, but I would consider that a reasonable temp
I wouldn’t want to speculate on you battery cable connections without comparing them to the wiring diagram, but 27.5 at the solenoid (relay) is what I would want to see as long as that is the voltage under load.
-
When you replaced it did you get 24 volt? Also which breaker (amp wise ) is tripped? Might have parts for you> Free you pay shipping. Might have complete condenser fan assembly. Heavy sucker but same deal. Will ck tomorrow to see if it is still on shelf. Like Jon said check brushes. Simple fix and considered maintance item. Bob
-
Be sure the brushes move freely on their channel(track) and actually touch the armature.
JIM
-
What Jim said. My brushes were stuck in the holder resulting in a similar problem.
Ken
-
Bob, Ken and Jim, Thanks I will check the brushes! And Bob I will get the info on the breaker and get with you on the other stuff you have! Thanks a bunch for helping out! This thing is driving me flipping crazy! MT
-
As you use the AC the carbon brushes wear down and the resulting very fine carbon particles accumulate around the slide channel, add to that high humidity and or moisture from driving in rain, the particles pack/cake in to hold the brush. When this happens the brush does not move down the channel to remain in contact with the armature. When the brush looses contact with the armature, no current flows and the motor stops.
The brushes are fragile. Do not be too agressive when freeing them up. It is difficult to reach all, try a thin shaft and a light tap.
Changing the brushes your first time, if you elect to do so, will take at least 1/2 day and is not to be taken lightly.
When you don’t have anything else to do and if you like to do maintenance like that it can be fun. Prevost’s charge is hefty for the procedure and is worth it for one that can’t be bothered.
I don’t imagine anyone having to change them more than once in the RV application.
JIM
-
I doubt they need changing. Unless the coach has a lot of miles on it they might just need to be freed up if that is the problem. Two of my coaches had about 250,000 miles on them and the brushes were original when I sold the coaches.
-
I have the complete assembly used prevost fan I took out running/did not use over road air=heat. Let me know if you need it ;Mike will be in Nashville 27-29th at vanderbuilt so could bring it that far. Bob
-
Thanks Bob, I will know tomorrow. Got a friend stopping by to look at it! Thanks for letting me know! MT
Log in to reply.