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Topic: Voltage Swings with Dash Air (Read 638 times) previous topic - next topic

Voltage Swings with Dash Air

On a recent trip I noticed my dash volt meter (and VMSpc) would drop to about 12.2 v and then jump up to 15.2 v for just a second or two and then stabilize at about 13.5 v.  This process would occur about twice a minute.  I turned on the generator to run my roof A/Cs and to see if that changed anything.  It didn't change much but did slow down the frequency of the jumps.  I called the factory, they told me to check voltages at the isolator, they seemed fine.  However, I was checking with the dash air off.  After a short time on the road I turned on the dash A/C and noticed immediately that the voltages were jumping again.  So I turned off the air and all was fine.  Every time I turned on the dash air it would start to jump within a few seconds.  I have been reading the forum and think this might have something to do with the alternator sense wire.  I emailed the factory this morning but I have not received a response yet.  Any ideas? 
2000 U295 40'
Build 5635

Re: Voltage Swings with Dash Air

Reply #1 –
My coach was doing the same thing. It turned out to be my condenser fan. The circuit breaker was self resetting and the voltage would drop when it was on and go back up when  the breaker was off.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Voltage Swings with Dash Air

Reply #2 –
The dash air seems to be working fine, do I change the fan or the breaker?
2000 U295 40'
Build 5635

Re: Voltage Swings with Dash Air

Reply #3 –
Start the engine turn on the air and watch the condenser fan and see if it is starting and stopping. My fan was tripping the circuit breaker even though the air was cold. The fan cycled enough to keep the dash air cold. It took me a year to figure out what was causing the voltage swing. In my case it was the fan drawing to much power. The fan didn't spin freely like the new one did.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Voltage Swings with Dash Air

Reply #4 –
Could also be the same scenario with the AC clutch,check that too,cycling on and off.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Voltage Swings with Dash Air

Reply #5 –
Several of us have moved the sense wire location off the A/C circuit to a better location. Doing this will cure the false reading of the state of batteries when the A/C cycles on/off.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Voltage Swings with Dash Air

Reply #6 –
Where did you move it? 
2000 U295 40'
Build 5635

Re: Voltage Swings with Dash Air

Reply #7 –
I  put ours on the lug of the isolator that has the cable that goes directly to the start battery.  If you use this location make sure that you use a new self resetting breaker in the wire.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Voltage Swings with Dash Air

Reply #8 –
The same thing happened to me and it was the condenser fan and when it fail it shut the engine off. It was on the same breaker as the ecm.  Needless to say that is not so any longer.
2015 Born Free Royal Splendor on Ford 550 nonslide version
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Voltage Swings with Dash Air

Reply #9 –
Quote from: Pamela & Mike –
I  put ours on the lug of the isolator that has the cable that goes directly to the start battery.  If you use this location make sure that you use a new self resetting breaker in the wire.

Mike
You might want to re think that self resetting circuit breaker.  The FAA issued a notice, I can't remember what level, and I certainly can't remember how long ago, to not re-set a tripped circuit breaker in flight, after several inflight fires had occurred.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Voltage Swings with Dash Air

Reply #10 –
OT,

 I can't see not adding one more self resetting breaker to a coach that has over 40 will make a big difference.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Voltage Swings with Dash Air

Reply #11 –
Beavers had self resetting circuit breakers for a lot of coach functions.

And a marine 12 volt breaker panel also.

No problems
"Riding and rejoicing"
Bob & Susan
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Voltage Swings with Dash Air

Reply #12 –
It took me a while to do some digging, but I did the test requested by craneman and realized that the condenser fan was the problem as described.  Thank you so much!  Headed out today to find a replacement.  Also, looked at relocating the sense wire and it appears that project has already been done by the PO.  I tried to upload a picture, but not sure it worked, but anyway I noticed that the compressor breaker (the one on the end for my year model) has nothing on the end terminal, not even the nut.  The compressor does work but not wired through this breaker.  I noticed in the battery compartment that a wire with an inline fuse is connected to the positive terminal and wired to a relay that is strapped to the chassis.  I can't see where the wire goes except into the engine bay.  Any ideas?

Thanks everyone for your help. 
2000 U295 40'
Build 5635

Re: Voltage Swings with Dash Air

Reply #13 –
I see the picture uploaded.  The terminal I'm talking about above is labeled #2.  Can anyone identify ALL the parts on this picture by number for future reference?
2000 U295 40'
Build 5635