1979 fuse problems
Thread Starter
|
New User
Joined: Apr 2011
Posts: 4
Likes: 0
1979 fuse problems
recently bought a 1979 ford f250, 4wd, and when we turn on the heater/AC the fuse burns out. likewise, replace the lighter and as soon as we use any load on it, it burns that fuse out too. any suggestions on where to start? thanks!
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
First verify that you are using the correct size fuses, which should be written on the fuse panel. If the fuses are the correct size, then the heater is likely shorting out because of a short to ground downstream of the fuse (which must be found by inspection) or a bad blower motor. The lighter issue may be that the lighter you're using draws too much current for the factory wiring (assuming the fuse size is correct).
Thread Starter
|
New User
Joined: Apr 2011
Posts: 4
Likes: 0
the fuses are the correct size, it just seems like a bigger electrical problem now that 2 different circuits are burning out. the lighter was replaced with an new socket and before I connected it, checked the power source with my volt-ohm meter and was getting 12V DC out.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
I've had issues with replacement cigarette lighters burning out the factory size fuse (assuming this is what you're doing). I think the newer ones draw more current than what these trucks were designed for. I wouldn't attribute that specific issue to a problem with the truck. Just don't use the lighter you're using. The heater would have to be a separate issue; the two circuits don't have anything to do with each other (from the factory, at least).
More Turbo
Joined: Nov 2006
Posts: 538
Likes: 11
From: Great N/W
Since you have 2 issues with the same results, your idea of a bigger electrical problem may be accurate. 95% of ALL electrical problems are poor or missing grounds. I would start by verifying all the grounds, make sure they are making a good connection. Battery to block, block to frame, and block to body. The block to body one on the firewall is commonly missing, but an important piece.
Senior User
Joined: Jan 2008
Posts: 427
Likes: 1
From: Irondale, Al.
Does the fuse blow at any fan speed? Mine would blow the fuse on high, later found a loose connection at the fan switch.
Trending Topics
Thread Starter
|
New User
Joined: Apr 2011
Posts: 4
Likes: 0
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Highly doubtful, but you can easily check that by measuring the voltage across the battery terminals with the engine running.
