blower motor wont turn on

[Jmizioch]

Was leaving the park yesterday and tried to put on the defrost and nothing..... This has happened in the past once or twice but always came back on a minute on so later , this time nothing.... checked fuses and relay both are fine
2018 Jayco Precept 35S.........need some ideas before i bring it to Ford I have the Triton V10. Thanks, John M

[JFlightRisk]

If you're sure all the fuses and relays are good, it's down to either a bad wire connection, bad ground, bad switch, or motor.

[JimD]

Not sure if this test is beneficial or not. If you switch to air conditioning mode, does the ac compressor clutch engage? If it does that should indicate the switch is at least receiving power and switching.

I would guess that the output from the switch feeds separate relays for the blower motor and ac compressor.

How did you determine that the relay is good? Did you swap it with another one?

[craigav]

I would research this "Ford Blower Motor Resistor" as these go out more often than you may know, and commonly available at most all Auto Parts stores. The same resistor pack is used on many ford models. When these fail, most commonly one speed such as high will still work, but in other cases no blower action at all. This obviously isn't the only reason you could have the problem, however when you stated this happened once before and started working again, generally speaking that indicates the issue is not the fuse as once a fuse blows, it stays blown. Other causes certainly could be a loose connection, my suspicion though would be the "blower motor resistor" pack. ~CA (also, you could take it out and inspect it, if it appears burned then you would know, I would have to lookup exactly where it is, but commonly located near the blower motor itself and half is in the blower housing, and the wire plug in half is outside of the blower housing, likely under the hood).

[RPR]

Do you have heat blowing through the dash or floor vents?

[Jagiven]

Welcome Aboard!

Was the fan on? and it just did not switch to Defrost mode, or was the whole assembly dead?

If it did not want to switch modes, check for a vacuum leak, probably at the heater box outlet. Someone posted a few years back, that their vacuum line was not hooked up right. Unfortunately I do not recall the details. My guess it was about 3 years ago, so it was probably 4 . I am assuming your Precept is still using vacuum to control the heating distribution.

If the whole assembly was dead, based on what was noted above, I would check the relay 1st (easy item to access), and then the switch, which might require the dash to be pulled apart.

Please post your findings

[RPR]

With all the electronics now a days the doors that direct the air flow may be electric operated. Son in law just replace vent motor on his car. Had one electric motor that directed air flow to drivers side and another that directed air flow to passenger side. Darn computers. Lol