I have a 2003 Motorhome built on a 2002 F53 Chassis with AC/Heat blower issues. Trouble shooting I've done; Tested all fuses and relays, check to see if all of them have power, I've checked Blower motor resistor for continuity, checked the blower motor with 12V. What I have found is that I have no voltage at the resistor, or at the control unit. Nothing at either location. I have power at all the fuses all the relays and all the fuses and relays have been check and I've also replaced all of them just to make sure. I put in a new resistor just in case nothing. Can any one tell me why I don't have 12V at either the control unit or the blower resistor. What wires should be hot and how can I trace them back to see if there is a break or something disconnected in the harness?


Thank you
Deric

 

Using a toner should enable you to trace the leads.

 

Am I thinking correctly that I should have 12V somewhere at the control when ignition is on and control unit is on?

 

RV_Tech shouldn't I see power at the controls and at the resistor 12v?

 

Tracing wires all morning... Found the lead from the Ford Chassis Harness that was labeled Blower and followed it to an undocumented Bosch Relay. I have 12V power going into the relay but nothing coming out of the relay. Swapped relays still nothing...

 

Back of control unit there is no 12v found.


Undocumented relay pink wire goes to back of control unit.


original Ford chassis blower lead goes to undocumented relay.

I traced wires from the control to a relay that's not documented.


I also found the blower wire from the Ford Chassis harness label Blower traced it to the same relay. Replaced the relay still nothing. Power is going into the relay but nothing coming out.

 

Do you have power to and through the switch?. The switch has to close the relay in order for power to flow.

Steve

 

No Steve I don't have any power to the switch or thru it. I'm stumped...


I think the Pink wire in to the control in the center should be the one with 12v power but I can't for the life of me figure out why there is not 12V there when the key is on and the switch is in a position other then off.

 

Can you verify when you have the switch on, there is continuity through the switch.

 

should there be 12V at white arrow middle pink wire?

I've checked both switches the is no voltage going to either switch. The green arrow is the blower speed control, and the white arrow is the MAX/AC-FLOOR-DEF control switch. Shouldn't one of them have 12V coming in to it to go to the relay to energize it or am I backwards? I'm checking continuity right now thru both switches. Will let you know.

 

I'm not sure which switch to check continuity on and not sure how to check it. Which two leads/wires should show continuity with the switch on?

 

I can't find a schematic for this control panel is it not an Evans?

 

Steve when in the diagram attached when I supply 12V to this lead everything works. Any suggestions?


Thanks

 

And you located the 25 amp fuse and you tested it with a meter to verify continuity?

 

It's not quite that simple as usual. I wish it was. Traced that wire hoping to find a 25 amp fuse and ended up all they way back at the battery control solenoids. Yippy!


Checked all the fuses all are good... found that I have no 12v power to about 4 of the 6 wires in the connector that's terminated their. I put a 12 volt jumper on the wire that runs the AC/Heater control and the blower works. Sure looks like I have an issue at the two solenoids/printed circuit board/fuse holder for the house batteries and the chassis battery. Just started researching that setup. UGH nothings easy...


Do you know where I can get some information on that setup?


Motorhome is a 2003 Forrest River Georgetown 303


Thanks