2008 Contessa Dash Air Conditioning InOp

[Peter Whiting]

Went for a weekend trip and the dash air conditioning is inoperable.  No heat, no air, no fan.....nothing.  I checked fuses F29 and F83 and both are good.  I used the spare relay to check ISB1-R2 and CFR-R17 and the relays appear to be good.  Does anyone have any suggestions?

[Steve Huber Co-Admin]

Peter,
Pg 10 of the 08 Contessa Wiring diagrams in Coach Assist shows a 20A fuse (VEC-1) providing power to the Dash control switch. I think its located in the rear run box.
Steve

[Peter Whiting]

VEC-1 fuses the dc voltage to the ignition switch.  I checked the fuse and it is good,.  I will now go in with a multimeter and see if I can isolate where the fault is. 

[Peter Whiting]

I have power to F29 (and the fuse is good).  Does anyone know where I can find SCS.  Wiring diagrams are good but not helpful in finding locations.  I think there is a VC PCB.  Does that stand for VC Printed Circuit Board?  If so, where would I find that?

[Steve Huber Co-Admin]

Peter,
SCS is a connector up front but I don't know where. You can check for voltage at the VC  connectors on the front bay PCB. I use  a pin to pierce insulation rather than disconnect connector. Another approach; except for the fan, all the functions are controlled by vacuum routed appropriately by the dash function switch. Verify you have vacuum running to it from the vacuum pump under the front cap. It's on the passenger side high up. The switch also needs 12v from F29 so you should be able to verify there. See pg 116 of the 09 Contessa diagrams.
Steve

[Peter Whiting]

Hi Steve,

I was able to determine the blower motor is functioning by applying 12volts directly to it.  I removed (with great difficulty) the dash control panel (see attachments).  I determined there is 12 volts coming in to the Red/Black and Black wires going to the back of the vent control.  I plan tomorrow to apply 12 volts to the white wire that is on the back of the fan speed switch to make sure there is not break somewhere between the switch and the motor.  If there is continuity, then I suspect the dash control panel has failed.

I have determined it is a Ford part but cannot confirm the part number as it does not appear on the panel anywhere.  Do you know where the control panel can be purchased?

Thanks in advance.

[Steve Huber Co-Admin]

Peter.,
Verify the vacuum activated functions work correctly before replacing the unit. With the ignition on the vacuum pump should run and the doors should activate as your select different functions such as floor hear, defrost, etc.
Steve

[Eric Maclean]

Peter
Are you sure that panel is a Ford piece? The reason I ask is the earlier Beavers like mine used a Chevy Cavalier controller.
I have heard that some of the units used GM truck controllers but I can't confirm that .
Are there any numbers on the back of the controller you have ?

The earlier Beavers used ACME A/C parts for there dash air systems maybe this link will help

http://acmeairparts.com/rvacheaterparts.html#!/Control-Heads-&-Parts/c/16022614


Hope this helps
Eric

[Peter Whiting]

Hi Steve…..yes, you can hear the a/c doors cycling when you rotate the switch. 

[Peter Whiting]

Eric, it appears to be a Ford part.  There are no readable numbers on the mounting plate but the temperature control switch has a Ford emblem on it.  The other two switches have no part numbers. There is a panel on the Acme site that appears to match this one perfectly.

[Eric Maclean]

I've been doing a little looking around for you and also found this same part number as the ACME part

https://www.fesyadekor.com/index.php?main_page=product_info&products_id=719441

This link I couldn't get to open but you may have better luck it appears to be the wiring for that control head in a Beaver coach.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.serenitysys.com/beaver/archives/ACME-doc20110316084645.pdf&ved=2ahUKEwjJvOTRzavyAhVPVs0KHQSSBZsQFnoECC8QAQ&usg=AOvVaw0D4FKaEHZgUEAvwzfXRM8g&cshid=1628776969844

Hope this helps
Eric

[Eric Maclean]

Peter
Remembered when diagnosing your blower motor system most systems have a blower resister and some even have a relay for high speed operation. At this point it would pay to have a wiring diagram to properly test them out.

PS    if y can find the blower resistor will see a diode shaped piece attach to it this is a thermal fuse not a diode it's purpose is to blow shutting down the blower motor in the even of an over heat at the blower resistor ( usually indicative of a blower motor drawing too much current)
This may be your problem for once the thermal fuse blows you will have no power through the resistor block and of course no blower motor operation.

Hope this helps
Eric

[Peter Whiting]

I am stumped....and that doesn't happen too often.

I am repeating some of the things previously reported as checked.

I removed the control panel and ran continuity checks on the mode control switch and it checks out.

I ran the blower motor by applying 12 volts directly to it.

I checked the resister and it checks good. The thermal fuse is good.

I have 12 volts at the Vent Control pins (top and bottom as shown on 2009 Schematic HVAC, link below) when unplugged. 0 volts when plugged into the switch.

I have 0 volts at the plug going into the resistor on any pin.

I have 0 volts coming from any pin from the fan speed switch.

My questions are:
1) how does voltage get to the speed control switch? 
2) Why is voltage dropping to 0 when the vent control plug is plugged in?
3) Could the control panel be bad (I don't think so)
4) Anyone have any other ideas?


Links to schematics: http://www.serenitysys.com/beaver/archives/ACME-doc20110316084645.pdf  (page 1)

https://www.beaveramb.org/resources/Documents/Technical%20Forum/Coach%20Assist/Wiring%20Diagrams/2009%20Contessa%20_%20Monterey%20Wiring%20Diagrams_Optimized.pdf  (page 116)


Thank you in advance for anyone who can offer suggestions.

[Steve Huber Co-Admin]

Peter,
Seems that the fan is central to the 12v issue. I'm wondering if the fan motor is pulling down the voltage. It's possible that the 12v you applied had enough current capability to run it but the HVAC system doesn't. Try unplugging the fan and see if you have 12v at the wire going into the fan. Also, note that the fan has an independent ground so if you reverse the power & gnd connections it will run, but in the opposite direction. Another possibility is that the fan resistor has changed value and is not allowing the needed voltage. You could try bypassing the resistor to verify.
Steve

[Peter Whiting]

Steve…..thanks but there is not 12v present at either the plug going into the motor or at the resistor.  With the 4 pin plug that goes into the vent control switch unplugged, I get 12v at the red and black wired pins.  Once plugged back in the voltage is 0. 

I jumpered the resistor this afternoon and that didn’t work either.

Where does the power to the speed control switch come from?