Dash A/C wiring diagram…08 Navigator

[Ivylog]

I’m not finding any fuses in the FRBox for the dash AC and I’m not getting a signal to the RRBox from the dash controller for the relay that controls the clutch on the compressor and to the fan on the evaporator…2 fuses on the board check good. System works well when I jumper 12V to the coil in the relay^^^, energizing the clutch and the fan.

All functions on the 3 knob controller seem to work but no signal to the AC relay in the RRBox.. The function knob (Off, Max…….) appears to ground the 10 different wires connected to it… no 12V power to it. Various positions puts a ground to different wires… must be a relay box in the dash somewhere.

Any one know the brand and model of the dash controller or wiring diagram?

[Frank McElroy]

Is your system low on freon?  If pressures are too low the low pressure cut off switch on the line coming out of the evaporator will prevent the compressor from engaging.

[Ivylog]

That’s what I thought and instead of using the small cans to add, I hooked up my 30 lb bottle, but the hose didn’t get cold and the clutch never engaged… should have. Put a gauge on and there was plenty of pressure.

No compressor signal from the front controller to the board in the RRBox.

As I posted above: “System works well when I jumper 12V to the coil in the relay^^^, energizing the clutch and the fan.” …No compressor signal from the front controller to the board in the RRBox.

Unlike older models of the front control, the function switch (Off, max AC, AC, 2 air flow locations, Defrost) doesn’t do the actual switching as it has 10 very small wires to/from it…older one had 4-5 large wires capable of doing the actual switching…7-10 amps. 

 

Edited June 21, 2021 by Ivylog

[Frank McElroy]

I think you have duplicate discussions.  I put a link to the file download on the Dash HVAC wiring diagram that I think you need on your other discussion posting.

[Ivylog]

I spent an hour searching and reading everything I could find on this before posting. I looked at your link/diagram and the vent control only has 5 heavy duty wires. Mine has 10 small wires that must go to a a board with relays.

Edited June 21, 2021 by Ivylog

[Frank McElroy]

OK, in looking closer at your picture, I see what you mean.  The control panel is slightly different.  Darn, I even tried searching on the rambling pushers group and keep coming up this the wiring diagram I already posted.  I'll keep looking.  This is a conventional and not a chassis multiplex coach right?

That control module looks like it's manufactured by Dorman.  By any chance is there a part number on it?

[Ivylog]

Not sure who I ended up with 2 threads.

Anyway, it’s now working because, as best I can figure, where I store it was 72 degrees, When I put it outside in 85 degrees to head to the West, it started working…go figure.

[Frank McElroy]

Well, it will be interesting to see what happens in the next few weeks.  In your earlier post you mentioned that the static pressures were fine and it wasn't a low pressure cutoff issue.  Then you move the coach outside where freon pressures would rise and now the compressor engages.  I'd be curious to know if, when the system is running, the high and low pressures look normal for outside temp and humidity.  If the answer is yes, then you are left with a sticking system pressure sensor or a bad evap temp sensor but in another post you mentioned that you bypassed the temp sensor.  So, if running pressures are normal and the temp sensor is bypassed, the only options left that I can think of are an intermittent electrical connection, or a sticking pressure switch.  If it happens again, your voltmeter and pressure gauges should easily sort it out.