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12 volt compressor question

When the 12 volt compressor failed to build pressure a few days ago, I found the normally open unloader solenoid was not getting 12 volts. The 12 volts comes from a small circuit board mounted on the 12 compressor relay (see photo).
On this board there are three black wires, one supplies the unloader, one goes nowhere and is apparently a spare and the third supplies something else. The "spare" had the same weather proof connector I needed so I am using it and everything is working again.
What is the function of this board? Where can I find a replacement?
The large silver stud goes positive when the compressor is running, closing the normally open unloader solenoid. When adequate pressure is attained 12 volts is removed, the compressor stops and the solenoid opens with a whoosh. It does look like there is a diode on the board, maybe for noise suppression???
Note, when that solenoid fails to close, not enough pressure is built up to complete the evacuation process for the slide seals and the slides cannot be moved. In our case we couldn't get them IN. I was able the hold my finger against the exhaust port enough to get just enough pressure.
Right now I don't know if I should try to repair this little board, replace it, or just do nothing. I think it would be possible to bypass the board and supply 12 volts to the solenoid manually in the future if necessary. I just don't like knowing that it isn't quite right.
Thanks for any help on this.
Dick
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: 12 volt compressor question

Reply #1 –
Quote from: Dick S –
The "spare" had the same weather proof connector I needed so I am using it and everything is working again.
 
Right now I don't know if I should:
1.  try to repair this little board
2.  replace it
3.  do nothing.
Sounds like you've solved your problem.  Since "everything is working again", I would vote for number 3.  But then I'm a lazy slacker...  :sleepy:
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 12 volt compressor question

Reply #2 –
Agree with Chuck. Just checked mine, thinking little box is a time delay to allow compressor to start before solenoid valve closed, but it isn't. Compressor starts and valve closes at the same time. When my bowl cracks or solenoid valve goes out, will probably replace with a regular water separator that I will drain manually.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: 12 volt compressor question

Reply #3 –
Chuck is a very wise lazy slacker!
I will go with him.
Dick
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: 12 volt compressor question

Reply #4 –
On pp 25 of the attached HWH 2000 Series manual, the small circuit board is identified as containing a diode.

The aux. compressor turns on in 2 circumstances: first when the air pressure switch closes because air pressure in the slide out seal air tank (or aux air tank) has fallen to the cut-in pressure set in the pressure switch.  Second, regardless of the pressure present in the slide out seal air tank, whenever the leveling system is inflating an airbag to raise the coach, the HWH computer sends a signal to turn on the compressor.  I believe the diode on the small circuit board is to isolate these 2 separate power sources (12v from the pressure switch and 12v from the HWH computer).
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: 12 volt compressor question

Reply #5 –
Quote from: Mark Duckworth –
On pp 25 of the attached HWH 2000 Series manual, the small circuit board is identified as containing a diode.

The aux. compressor turns on in 2 circumstances: first when the air pressure switch closes because air pressure in the slide out seal air tank (or aux air tank) has fallen to the cut-in pressure set in the pressure switch.  Second, regardless of the pressure present in the slide out seal air tank, whenever the leveling system is inflating an airbag to raise the coach, the HWH computer sends a signal to turn on the compressor.  I believe the diode on the small circuit board is separate these 2 separate power sources (12v from the pressure switch and 12v from the HWH computer).
Makes a lot of sense, Mr HWH was a smart cookie. If you waited for the pressure switch to turn comp. on, might not inflate bag enough to level coach and would just equalize and not turn compressor on.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.
 

Re: 12 volt compressor question

Reply #6 –
Quote from: Mark Duckworth –
On pp 25 of the attached HWH 2000 Series manual, the small circuit board is identified as containing a diode.

  Second, regardless of the pressure present in the slide out seal air tank, whenever the leveling system is inflating an airbag to raise the coach, the HWH computer sends a signal to turn on the compressor.  I believe the diode on the small circuit board is to isolate these 2 separate power sources (12v from the pressure switch and 12v from the HWH computer).
AH HA!.........My leveling system doesn't seem to "wake up" and add pressure to level when in sleep mode...But it will if you "interrupt" the sleep mode by turning on the ignition key..................I Wonder.....
'02 40' U320t  4010WTFS Build 6036 1 slide
Motorcade # 17841
SKP 151920
Retired truck driver
 5 million miler
Still have itchy feet for travel