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.

2 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 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.

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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