Stuck On Hi Heater Fan Motor!

[BATMANN]

I just got my Marauder 3 weeks ago and now today My heater fan motor is stuck on high and neither the steering wheel control nor the control on the dash work, now the only way to turn it off is to pull the fuse this really sucks can anyone help shed a little light on this for me? Has this happened to any other marauders?:help:
Thanks
Shawn
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[Wires]

There are two possibilities.

One. Your A/C controller (headunit, the thing mounted in your dash) is bad. This is the "master controller" so to speak for your AC system. it could be bad, and thus sending the "full on" or "high" signal to your fan speed module, regardless of the setting.

Two. Your fan speed module (which I have recently had the joy of replacing) is bad. The fan is connected to 12V, and the module varies the resistance in the ground circuit according to the command from the module. (using a FET, if anyone cares) I did an autopsy on mine, and discovered that there is a relay inside for high operation. It could be stuck, or some other part (like that FET, which stands for "field effect transistor") of the module could be defective. My money's on the module - especially if you can turn your headunit off and the fan still runs. The headunit sends only a control signal to the module.

The problem is diagnosis. The module is difficult to replace, and the head unit is expensive.

My recomendation is to either take it to the dealer to get it diagnosed or, if you want to do it yourself:

1. buy a module - I recommend sending a PM to "The Dealer," otherwise known as Ray - he's a great guy and very helpful with Marauder parts. Or, contact your dealer's parts dept. I happen to have my receipt handy:
part number: 8W7Z-19E624-A.

Don't bother to remove your module, just disconnect it from it's harness. It's directly behind the passenger side cylinder bank, with a %%$##!!!! heater hose in the way. Plug in the new module. The aluminum heatsink (finned piece of metal, you can's miss it) will get warm, and even hot if you leave your fan on low for a while. Don't set it on anything plastic. Try your AC fan, but don't run it too long. if it's ok, you can either pay your favorite mechanic to change it, or, drain your cooling system, remove said heater hose, and replace the module.

I had to remove the spark plug cover, and move the rubber strain relief for the coil wires out of my way to get my wrench on the screws to remove the module. You may have a different wrench and not have to do that. The strain relief is a hard rubber plug, and is quite large, and, in my case, was in just the wrong place.

If the module does not fix it, you're only out about 40 bucks, and you'll have a spare for when your module DOES go out. (chances are it will) Then, find a headunit and change it.

If you have access to a spare headunit, by all means, try that first, because it is much easier to change. Don't worry about the vacuum lines during diagnosis, just plug in the new one electrically and test the fan.

Good Luck!

[BATMANN]

Thank you Very much wires! that was super helpfull.. I am sure it must be a stuck relay, i will go thru the replacement process of the module, sounds like major fun! i will let you how it goes.
tcb
Shawn

[Seneca]

There are two possibilities.

One. Your A/C controller (headunit, the thing mounted in your dash) is bad. This is the "master controller" so to speak for your AC system. it could be bad, and thus sending the "full on" or "high" signal to your fan speed module, regardless of the setting.

Two. Your fan speed module (which I have recently had the joy of replacing) is bad. The fan is connected to 12V, and the module varies the resistance in the ground circuit according to the command from the module. (using a FET, if anyone cares) I did an autopsy on mine, and discovered that there is a relay inside for high operation. It could be stuck, or some other part (like that FET, which stands for "field effect transistor") of the module could be defective. My money's on the module - especially if you can turn your headunit off and the fan still runs. The headunit sends only a control signal to the module.

The problem is diagnosis. The module is difficult to replace, and the head unit is expensive.

My recomendation is to either take it to the dealer to get it diagnosed or, if you want to do it yourself:

1. buy a module - I recommend sending a PM to "The Dealer," otherwise known as Ray - he's a great guy and very helpful with Marauder parts. Or, contact your dealer's parts dept. I happen to have my receipt handy:
part number: 8W7Z-19E624-A.

Don't bother to remove your module, just disconnect it from it's harness. It's directly behind the passenger side cylinder bank, with a %%$##!!!! heater hose in the way. Plug in the new module. The aluminum heatsink (finned piece of metal, you can's miss it) will get warm, and even hot if you leave your fan on low for a while. Don't set it on anything plastic. Try your AC fan, but don't run it too long. if it's ok, you can either pay your favorite mechanic to change it, or, drain your cooling system, remove said heater hose, and replace the module.

I had to remove the spark plug cover, and move the rubber strain relief for the coil wires out of my way to get my wrench on the screws to remove the module. You may have a different wrench and not have to do that. The strain relief is a hard rubber plug, and is quite large, and, in my case, was in just the wrong place.

If the module does not fix it, you're only out about 40 bucks, and you'll have a spare for when your module DOES go out. (chances are it will) Then, find a headunit and change it.

If you have access to a spare headunit, by all means, try that first, because it is much easier to change. Don't worry about the vacuum lines during diagnosis, just plug in the new one electrically and test the fan.

Good Luck!
You can replace the resistor without draining the coolant had that problem with my car. I think it's held in with 8MM head screws It's tight but can be done. If thats the problem cost is about 40 some bucks from FORD. Good luck. Try Checking your head unit for codes. there are directions on how to do that if you do a search. Seneca

[Motorhead350]

I had to replace my A/C head unit and it was like $560 new, but I found one at a junkyard for $260 with a six month warranty. Mine was out of a Grand Marq and I believe we can only use parts dating back to 2002. Changing the unit is super easy.

1. Pull the silver grain off the passenger side and it's easiest to start with the door open and just poping it off until you go past the clock.

2. Disconnect the clock by un-clicking it. (is that a word?)

3. Unscrew the four bolts for the A/C head unit.

4. Snap out the wires that are clicked into the rear and reverse the process for the install.

P.S. Be sure to disconnect your battery before you do any of this because I blew two fuses the first time I did this.

Hope this helps you.

[Wires]

You can replace the resistor without draining the coolant had that problem with my car. I think it's held in with 8MM head screws It's tight but can be done. If thats the problem cost is about 40 some bucks from FORD. Good luck. Try Checking your head unit for codes. there are directions on how to do that if you do a search. Seneca

I'd love to see it done without removing that heater hose. (and the hose that's in the way of that hose) I tried and tried, then I tried some more. At one point, it hit me that I could have had the hoses out by then. So I removed them.

I think that the hose and plenum have more give to them then I was using - I was too gentle with them. Anyway, it's back there.

No one answered my heater hose question - can anyone tell me which hose goes where?

[fastblackmerc]

No one answered my heater hose question - can anyone tell me which hose goes where?

Your supposed to mark them or remember where they go.

[Wires]

Your supposed to mark them or remember where they go.

Yes, I realize that. However, now that I've made the mistake, I need a little help.

I know everyone is busy, but if someone could take a quick look at their heater hoses and let me know I'd greatly appreciate it.

[Seneca]

Isnt there a short one and a long one.? I cant remember for sure.. It's been a while. Sorry I'm at work. i dont have my car. are they both the same size?

[Wires]

One is shorter. It has a single, 90 degree bend.

The longer one goes to the pipe on the passenger side of the engine, which runs to the top "crossover" pipe.

From the other post, I think the consensus is that they do cross - the short 90 degree hose goes from the passenger side core pipe to the pipe behind the engine.

The longer hose goes to the driver's side core pipe.

I know a lot of folks have the cooling mod, which changes the plumbing around there, somewhat.