Aircon fan always running?

[jose1969]

I have a ford explorer 2000 that blower fan always running. Even I turn off the EATC. Once I turn on the key ignition, the blower will run. What seems to be the problem? As soon as the key ignition turn to on, fan will run. Please help me!

Thank you!

 

[J_C]

I suspect a leaky transistor. Trying to explain how to troubleshoot that, well here goes...

You'll need a multimeter. On the transistor pack on the firewall, there would be a 12V lead and a transistor base drive lead. The transistor base should have little to no voltage when the fan isn't running. If it has little to no voltage then that pack transistor is leaking.

If it does have significant voltage then the head unit in the dash is the problem.
If you arrive at that determination then it's up to you whether to tear it open and probe around to find a component specific fault or replace the whole unit.

That it doesn't run till the key is on "might" indicate the head unit rather than the firewall module but I am not certain of that. I am only generalizing, don't have the auto climate feature. Others may have knowledge of more specific issues unique to these units.

The other option since it doesn't run with the key off is to just ignore the problem. It's not entirely a bad thing because if you turn it to off, making the compressor stop, then with the fan still blowing that will remove more moisture from the ducts so they don't mildew as easily... unless it is always blowing too fast even on low fan speed setting.

 

[jose1969]

Where is that transistor located? I can't leave it that way cause the blower is noisy. Always running once the ignition is on. Specially if the eatc is off.
You said transistor or resistor?
Thank you!

 

[SoNic67]

There is no transistor. Probably the blower relay located inside the engine compartment has the contacts welded shut - replace the relay.
See below:

 

[jose1969]

I will change the relay. I'll be back for the result.

Thank you!

 

[J_C]

Sonic you have the wrong diagram for the manual climate control instead of EATC.

On the EATC circuit, one transistor for the speed control is what some erroneously call the blower motor resistor (module), mounted on the firewall. A second likely transistor is located in the EATC head unit to bias that speed control resistor, with that head unit on a EATC replacing what is on the manual diagram as "Function Selector Switch Assembly".

My thinking is that even if the blower motor relay is stuck on, the EATC module itself should still be in control of if it turns at all. In other words the relay has to be on for the fan to run in the lowest mode possible, so the EATC has to be in control of the fan still (or not in a failure condition).

I state this with the assumption it is running faster than the slowest possible speed since the OP reports it is noisy. The other option for particularly noisy might be a shot motor bearing so it is louder than it would otherwise be, in conjunction with another fault.

 

[J_C]

I am not certain if the following EATC diagnostic procedure is correct for your model year EATC but it is worth a try:
http://www.fordforumsonline.com/threads/electronic-automatic-temperature-control-codes.32/

Others have been told that a code 52 on that test indicates the firewall transistor module is bad (aka blower resistor as I mentioned in my last post):
http://www.justanswer.com/ford/7r8g...code-052-climate-control-eatc-diagnostic.html

 

[jose1969]

Thank you J C! It's a resistor not transistor? I've tried to search the blower transistor no result. Always showing is a blower resistor. There is another resistor on EATC?

 

[J_C]

It is not a resistor.

On the manual, non-EATC version there is a resistor module. Because the manual has a resistor module, many people refer to the transistor module on the EATC version as a resistor module when it isn't, rather it is used instead of a resistor module when you have EATC.

So... if someone says "resistor module" they mean "transistor module" when it is the EATC version. The primary difference to you is that the transistor module costs 3X as much and is a different part #. The part # you would need IF it's the problem is XL2Z19E624AA http://www.rockauto.com/catalog/moreinfo.php?pk=3102411&cc=1372407


Keep in mind I don't want you to fixate on it just yet. If the base drive voltage to that module does not vary with the head unit fan setting then it's not the problem. In other words when the head unit is supposed to have the fan shut off there should be practically no base voltage to the module.

 

[SoNic67]

Test procedure and diagrams for ETAC A/C (scroll down to #7 or so):
http://www.explorerforum.com/forums/showthread.php?t=335006

You still want to check first the blower relay - it makes sense for your symptoms: That relay has to be either commanded "ON" all the time by a defective ETAC module or have the contacts melted together. No matter what the "resistor" (blower speed module) does.

 

[jose1969]

Relay was replaced didn't fixed. I bought a blower resistor. Then when I pulled my resistor is not the same. I went to dealer and it cost $160.00 hopefully this is the problem.

 

[J_C]

Yeah, a dealer charges a premium for it. The Motorcraft part is $72 at Rockauto and other brands down closer to $55. If you bought the dealer part and didn't install yet, I'd take it back for a refund.

If you are handy with a soldering iron, you can DIY replace the transistor on those for about $13 and some misc. minor parts (solder, standard heatsink grease, 2 bolts, lock washers and nuts).

http://www.explorerforum.com/forums/showpost.php?p=3278612&postcount=5
http://www.explorerforum.com/forums/showpost.php?p=3278864&postcount=7

 

[SoNic67]

I have a ford explorer 2000 that blower fan always running. Even I turn off the EATC. Once I turn on the key ignition, the blower will run

That module will not provide the constant 12V that makes you fan running all the time, even if is broken. The most it can do is to keep the speed at the maximum once you turned ON the ETAC (therefore applying power to he relay) , but not before.
Unless ETAC activated the relay all the time, witch will be stupid...

 

[jose1969]

I've already ordered at o'Reilly for $80.00

 

[SoNic67]

Let us know what happens

 

[jose1969]

SUCCESS!!!! Replaced the transistor and it fixed. I want to upload/attach the picture but I don't know how. I tried to upload it, but it asking a url link. The picture is in my phone. Anyway, thank you guys for all the help, ideas and recommendations. You guys are awesome!