Blower motor will not turn off

SATIAR2001

MEMBER
2000 FORD F-150
5.4L
V8
4WD
AUTOMATIC
210,000 MILES

Hi, I came back to school and realized my battery was dead. I got a jump and drove it to AutoZone and got it charged and got both my battery and alternator tested which were both good. I checked all relays and fuses and all were good. I got home and turned my truck off and realized when I pull my key out my outside are temperature and compass is still on and my A/C is still blowing making me manually turning it off. I’m pretty sure that is what caused my battery to drain. Any thoughts on what it can be? Thanks in advance.

Tuesday, January 29th, 2019 AT 7:29 PM

2 Replies

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

Hello,

It sounds like the blower motor control relay is stuck on causing the blower motor to keep running. but to be sure here is a guide to help test it and the location of the relay with the blower motor wiring diagrams so you can see how the system works:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Images (Click to make bigger)

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Monday, April 19th, 2021 AT 11:19 AM

BMDOUBLE

MECHANIC
1,139 POSTS

With multiple accessories remaining on, it sounds like a classic case of water in the central junction box and GEM module, caused by a leaking windshield. Remove the two large square connectors on the back side of the interior fuse box under the driver side of the dash, with a ratchet and a 10mm shallow socket. Inspect for water and green corrosion. Extremely common and any major short to power issue that I ever get on a heritage F-150 always seems to be water here.

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Monday, April 19th, 2021 AT 11:19 AM