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Aug 7, 2000 | 06:22 PM

barbercb

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Short???

Here's a good one. 1985 F150 5.0 AOD. My AC fan only works when in full position the low/medium and medium high setting don't work. When I start the truck and run it around with the AC off the temp stays at about the 'O' in Normal. When I turn the AC or fan on it begins to get hotter until it reaches past the 'L' meaning real real hot. When I turn it off it begins to fall immediatly but never gets back to the 'O'. Any reasons why this may happen or how to fix it?

Aug 7, 2000 | 10:21 PM

kioolt

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Joined: Aug 1999

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From: Bel Air USA

Short???

I believe your blower problem could be your blower resistor. It only affects the speeds below high.

Aug 8, 2000 | 07:36 AM

RGAZ

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Short???

kioot is right. The fan control is based on a blower resistor pack.

The truck overheating is a different problem though. It sounds like when the AC is running the truck overheats, right? Well then you could have a bad fan clutch, bad radiator, or maybe you are missing the fan shroud that forces the air to come through the radiator and condensor. I would check the fan clutch first, by listening at idle with the ac on. As the truck warms up, the fan should get louder. If it doesn't, there is a good chance it is not pulling enough air through the radiator. If you are missing the fan shroud, get a junkyard replacement.

Good luck,
Randy

Aug 8, 2000 | 03:38 PM

barbercb

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Short???

The only time the truck overheats is when the fan is turned on. Meaning AC or just vent. When the fan is in the off position it runs fine. That's why I thought it was real odd. It's not a gradual heat up either with in about 1 minute it's past the 'L'. Turn the fan off and with in a minute it's back down to say the 'R' or 'M'. I'd think if it was soemthing putting a big pull on the cooling system it'd take alot longer for the change to take place.
Where is this resistor pack?
and thanks!!!

Aug 9, 2000 | 10:21 AM

deleontow

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From: Banning CA

Short???

The resistor pack is located near the blower motor on one of the air ducts. It has tree wires going into it, unplug and remove the two screws holding it on. You may also have a bad switch, if the blower motor is bad, drawing too much power it may have caused the resistor pack to go bad, and also may cause the gauges to work inproperly.

Dave

http://a2ztowing.homestead.com/a2ztowing.html

Apr 27, 2001 | 10:01 PM

wrenched

Cross-Country

Joined: Dec 2000

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From: Northern MS

Short???

Hopefully you've got the problem solved by now, but the answer is in the blower motor resistor (in my '94 f-150 under the hood mounted on the blower housing). Although the whole assembly can be replaced for about $18, the actual culprit is the 'thermal fuse' or 'thermal cut-off', which is the little cylindrical electronic part with the plastic cone on one end. It can be replaced for about a dollar from Radio Shack or many other electronic supply houses. The original is rated at 121 C (centigrade). I couldn't find the exact replacement, so I used a 128 C, and it seems to work just fine. Make sure you replace it with the cone-shaped end going the same direction as the old one was.

Apr 28, 2001 | 08:52 AM

raycer

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Short???

I have an 85 F-150 w/5.0 and my ac was doing the same thing....not the blower part, but heating up when the ac was on. the ac clutch finally went out, turns out that the compressor was bad, causing the extra load on the engine, and therefore the extra heat. Got to the point where the ac clutch just couldn't take the load, and went south. This is from my ac guy, so maybe the heating problem in yours is the compressor on the way out. My guy said ford compressors are somewhat notorious for this, but mine did fine for 14 years, so go figure.