select Member Services on website to join

Author Topic: Fantastic Vent Fans  (Read 1691 times)

Don White

  • BAC Member
  • *
  • Posts: 11
Fantastic Vent Fans
« on: August 18, 2019, 05:08:41 PM »
Hi,

I am having a problem with 2 of the 3 vent fans in my coach.  They all have multiplex on/off wall switches in addition to the controls on the fan unit itself.  The fan in the kitchen area works as it should, the multiplex switch controls power to the unit.  When I turn the switch on the vent opens and the fan starts.  The other 2, shower area and toilet area, the multiplex switch doesn't do anything as far as I can tell.  I have to use the controls on the fan unit itself in order to operate it.  Both fans operate as they should using the controls on the units.

When I turn the multiplex switches on the green LEDs on the Intellitech PMC module comes on and they go off when I turn the multiplex switches off.

Please let me know if you have any ideas on what the problem is or have any trouble shooting suggestions.

Thanks,
Don and Anna White
06 Marquis Jade IV C 13

Don White
2006 Marquis Jade IV C13
1999 Jeep Wrangler
Hydralift
2006 HD Fat Boy
1997 Safari Serengetti

Fred Brooks

  • BAC Member
  • *
  • Posts: 673
  • Thanked: 346 times
  • RVIA Certified Luxury Technician 49 years, Retired
Re: Fantastic Vent Fans
« Reply #1 on: August 18, 2019, 07:39:44 PM »
    Don,

How are you operating the two fans manually? Fred
Fred & Cindy Brooks
2000 Marquis, Jasper
C-12 Wild Cat (U of A)
2014 Honda CRV
Proverbs 3: 5 & 6

Scott Shearer

  • BAC Member
  • *
  • Posts: 40
  • Thanked: 17 times
Re: Fantastic Vent Fans
« Reply #2 on: August 18, 2019, 08:18:06 PM »
If your Marquis is like our Thunder,  the Multiplex switch doesn't supply the power to the fan, it's a one amp switch circuit that triggers the fan controller to raise and lower the lid. Since the green light on your Intellitec module lights, the switch and Intellitec module are probably ok. You might have a bad lift motor or a bad connection at the fan (orange wire I believe). You could also have a bad controller in the fan.
Scott

2006 Patriot Thunder
Lexington IV 40'
Cat C13
2015 JKU Hard Rock

Fred Brooks

  • BAC Member
  • *
  • Posts: 673
  • Thanked: 346 times
  • RVIA Certified Luxury Technician 49 years, Retired
Re: Fantastic Vent Fans
« Reply #3 on: August 18, 2019, 09:18:03 PM »
    Scott, you are correct. The orange and white wires are just for the lift motor to raise the lid. The red and white wires are the main 12volt power to the fan for the fan motor, thermostat and the pc board.
   What is strange is why 2 fans would quit being triggered from the multiplex output source. They are both general vicinity so I am wondering if there is an open circuit somewhere between the fans and the multiplex output signal. Fred
Fred & Cindy Brooks
2000 Marquis, Jasper
C-12 Wild Cat (U of A)
2014 Honda CRV
Proverbs 3: 5 & 6

Joel Ashley

  • BAC Member
  • *
  • Posts: 1664
  • Thanked: 539 times
  • OSU Class of '73, Oregon Native. RVing 34 years
Re: Fantastic Vent Fans
« Reply #4 on: August 19, 2019, 03:58:08 AM »
Don, I assume you’ve checked the 10amp mini-fuses on the multiplex module.  On ours, there is a fan on each of fuse positions 8 and 9 of module #2 (“B” in my photo).  The Master still shows a green lamp even with a missing or bad fuse.

Joel
Joel and Lee Rae Ashley
Clackamas, Oregon
36.9 ft. 2006 Monterey Ventura IV, aka"Monty Rae"
C9 400HP Cat
towing a 1997 Ford Explorer Limited, aka "Pearl"
The following users thanked this post: Fred Brooks, Frank Bergamo

Scott Shearer

  • BAC Member
  • *
  • Posts: 40
  • Thanked: 17 times
Re: Fantastic Vent Fans
« Reply #5 on: August 20, 2019, 01:47:08 AM »
Don,

This is based on how our Thunder works, your Marquis maybe different. Here are a couple things that you can check. In the multiplex closet, on the righthand side, there are three purple Bosch relays mounted on a board that are controlled by the fan (multiplex) switches. These relays do not provide any power to the fan but rather, when closed, complete the circuit to trigger the fan controller to open the fan cover. You should hear the relays click when the multiplex switches are turned on, the relays will be fairly warm when energized. Check the relays and connections on the PCB. You can test the fan circuit and controller by pulling one of the relays and jumpering the normally open terminals. If the circuit and fan controller are good the fan cover should raise.
« Last Edit: August 20, 2019, 04:13:03 AM by Scott Shearer »
Scott

2006 Patriot Thunder
Lexington IV 40'
Cat C13
2015 JKU Hard Rock
The following users thanked this post: Fred Brooks

Don White

  • BAC Member
  • *
  • Posts: 11
Re: Fantastic Vent Fans
« Reply #6 on: October 06, 2019, 06:04:01 PM »
Hi Scott,

Thanks for your response...I'm just getting back to this so apologies for the tardy response.  Any idea where I would find the relays?  In my coach I have found the Intellitech boxes located in a cabinet underneath the dinning room table, cabinet behind the toilet, in a cabinet on the left wall above the drivers seat. and in a compartment underneath the bed.  None of them have the 3 Bosch relays you speak of.  BTW the fan in the kitchen has now decided to disregard the multiplex switch like the other 2.  Power in numbers I guess.

Thanks again.

Don
Don White
2006 Marquis Jade IV C13
1999 Jeep Wrangler
Hydralift
2006 HD Fat Boy
1997 Safari Serengetti

Will Hansen

  • BAC Member
  • *
  • Posts: 47
  • Thanked: 15 times
Re: Fantastic Vent Fans
« Reply #7 on: October 06, 2019, 11:19:48 PM »
Just did some experiments with mine... not mentioned in this thread is the fact that the knob/crank that lets you manually raise and lower the hood has two vertical positions: pull it down to manually control the hood and push it up until it snaps into the up position to engage the auto (multiplex) feature. If you inadvertently pull on the knob to raise or lower the hood, the multiplex capability will be disabled. My multiplex doesn’t do anything unless the knob is ‘up’, the fan speed control is set to a number greater than 0 and my thermostat knob is set to a reasonable level. Multiplex even works when the on/off switch on the fan is set to ‘off’.

Good luck!

-Will
Will and Carla Hansen
Zoe the Yorkie-Pom (ol' Eagle Bait)
2007 Contessa Laguna
C9 400hp Cat
2015 RAM 1500

Scott Shearer

  • BAC Member
  • *
  • Posts: 40
  • Thanked: 17 times
Re: Fantastic Vent Fans
« Reply #8 on: October 07, 2019, 08:56:40 AM »
Don,

In our PT, the vent fan relays are on the right hand side in the multiplex cabinet. The multiplex cabinet is in the bedroom closet, driver's side.  Your multiplex system is more complex than ours so the relays might be in a different location.

Edit: I tried to rotate the image but it didn't work. It should be rotated cw.

Scott
« Last Edit: October 07, 2019, 09:05:16 AM by Scott Shearer »
Scott

2006 Patriot Thunder
Lexington IV 40'
Cat C13
2015 JKU Hard Rock

Fred Brooks

  • BAC Member
  • *
  • Posts: 673
  • Thanked: 346 times
  • RVIA Certified Luxury Technician 49 years, Retired
Re: Fantastic Vent Fans
« Reply #9 on: October 07, 2019, 02:23:10 PM »
    Don, As Will suggests it is easy enough to check the "disengage" clutch by pushing and pulling on the knob. As a matter of fact, if the the knob is disengaged, you will hear the lift motor running non-stop until the issue is addressed. Unless the motor has quit working. On my coach, the transmission the lift motor drives finally wore out and I had to replace it.
  If you own a 12 volt test light, I would remove the vent trim on the ceiling and locate the orange and white wires. The orange wire is 12 volts with the wall switch on. You can use the white wire as the "ground". If you have power there, the issue is the lift motor. If the is no 12 volt, the problem is at the multiplex panel or relays. Fred
Fred & Cindy Brooks
2000 Marquis, Jasper
C-12 Wild Cat (U of A)
2014 Honda CRV
Proverbs 3: 5 & 6