[font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 05:46 PM (EST)[/font][p]My ac/heater fan doesnt work. The fuse is still good. How do I tell if I need a new switch or new motor? Or could there be something else wrong? It is a 79 f150 4x4 xlt.

 

This is not 100% but every time that I have had a switch go bad, normally one of the positions on the switch still worked. When it was the motor, nothing worked. This pertained more on older vehicles. Just a thought. Good luck.

Jakegypsum // Ford fleet, soup to nuts.

 

I would have to agree, usually one position will work if it is just the switch. However it could be a bad ground or broken power wire.
So remove the power wire from the motor and check for 12 volts with the switch on, and truck running. No voltage = bad wire or blown fuse, of course you said you already checked the fuse. The power wire could be broken off at the fan switch.
Next check the ground with an ohmmeter, should be close to 0 ohms between wire and battery negative post. If you have a good ground and 12 volts to the motor and it doesn't run the motor is dead.
Good luck.

Sparky

 

You guys won't believe this! Big Time smoke. I could really use some help. This is a April 86 F250 460 supercab, xlt, lariat. I say April because it has a lot of 85 parts on it, that has wasted my time, plenty of times.
I'm driving along, truck warm, have the AC on. I don't really recall if I had just switch it to recirculate on not, but all of a sudden smoke is pouring in the cab through the vents. I mean so fast that in the time it took me to hit the switch,(to off) and roll down my window, I was totally socked in, no visiblity and coughing and about to stop right in the lane.

Fortuneately it poured out the window just as fast, plus I had my head out the window for a second and was able to pull over. Now I look through the crack in the hood, don't see any fire, so I pop the hood, no smoke. By the way the smoke smelled natural,(like leaves, not plastic) I sniff around for a minute or two, let the truck air out.
By the way I'm heading to work.
I go back inside make sure everything is off, look under the dash, nothing. So I decide to fire it up, idle for a while, nothing. I put the vent on, fan starts because there is no "off" only "low", nothing, no smoke, go through the speeds, nothing. Move it to AC, gets cold, fan works, no smoke. The last thing to do is move it to recirculate, but I don't dare because everything is fine at this point, (except for the left-over smell) and I have to get to work.
So I get out of work, everything starts fine, I'm only using the fan and I'm keeping my window open. No need for AC because it's midnight and I don't want anything to happen now anyway. I want to try to duplicate it in the morning when I have time. Anyway, i'm a couple hundred feet from my house so I figure what the heck I'll turn the fan to HIGH to see what happens and the fan stops. I said "cool" finally something.
I have this pretty good electrical shop, they fixed my cruise control and stuff so I decided to go there. I drive over there in the morning, still no fan. Tell Henry the whole story and leave. He calls me back, you guessed it. Fan works, can't find a thing wrong with it. I've been driving it ever since, about 2weeks now, using AC and all the fan speeds.
Henry thinks there was a leaf on the blower motor resistor, that completely burned up, that it just so happened by the time I hit the switch the leaf was finished burning. He says the resistor is in the ducting path by design to help keep it cool. I don't know what to make of it. All I know is when you pour a botlle of Pinesol down your fresh air intake vents, the ones on the outside, under the windshield, it all seems to pour out on the drivers side right where your firewall meets your fenderwell. I guess that's where your rainwater goes that gets in there. Still can't get all the smell out though. Is it easy to get to the blower motor. I need to find some "char marks" or I'm going to go bananas.
Any ideas about the smoke or the smell. Sorry for the long post. This has to be the longest one ever for myself and with the most sentence fragments.
Vince