2005 e250 blower motor-what else can I try?

[JWA]

A bit late to the party here but this is my thought.....

When the blower is working using a test light probe the power wire checking for 12 VDC, when/if the blower stops working without any action on your part probe that same wire once again. Naturally we'll assume you do have power at that point while its working.

IF it stops check once again as quickly possible to determine if the entire circuit up to that point is working as designed. If no power the problem lies in the circuit, further diagnosis will be necessary, by going all the way through the circuit determining where a loss of occurs. Cycle the electrical controls to see if/when power returns.

When the blower stops you could also temporarily run a 12 VDC jumper wire to the blower motor contact to determine that blower is not intermittent.

To me this sounds like a wire is loose along its length and is interrupted as your van hits bumps or is otherwise jostled. When the blower circuit has failed with the key in "run" manually jostle wires under the hood and behind the dash board checking if that "restores" the lost power.

These problems can be frustrating to diagnose and I hope you're successful without too much more aggravation.

[arctictraveller]

The blower motor quit on my 2001, just when temps have dropped into the 30's. We were at the beach for Thanksgiving for a few days and the windshield was pretty fogged up when it quit. Fortunately, a couple raps with a screw driver handle brought it back to life for the trip home but the next time I tried it it was dead again. I'm assuming it's the motor and will be replacing it soon. Scroll to the bottom of the attached page for a trouble shooting guide https://www.rockauto.com/en/moreinfo...YZHrUQxQ%3D%3D

[B1200]

Hi JWA,
Thanks for the info. I just have some questions to understand your instructions as I am not that great on electrical things. You said to probe the power wire while it was working then check the entire circuit again once it quits. Isn't the power wire part of the circuit and if it quits working there will be no power anywhere in the circuit, assuming it is a short of some kind?
There are 2 power wires, one to the blower control switch, one to the master control switch, which both link together somewhere in the mess. The mechanic connected lights into both of those at the same time but they continued to show power even when the blower died.
Next he replaced all the connectors at the switches, blower motor and resistor and connected them with new wires and ran new wires to power. Essentially a whole new circuit (?) yes? Blower still did the same thing.
So doesn't that cover the same thing you were describing?
My next move will be to check out the relay as suggested by hogasm, though I am still unclear as to what that relay is for or how it effects the blower.
Thanks for your help. This really has been a mystery and a PIA!

[arctictraveller]

Here’s the wiring diagram to help explain how it works.

Power flows from the battery junction box through the blower motor relay closed contacts to the blower motor. Speed is controlled by the resistor bank and the function switch in the negative side of the circuit .