Fan only blows high

[Sactown]

Last year my vent fan died and a new BCM took care of it. Yesterday the fan got stuck on high, it will switch between def/vent/floor just fine and temp adjust, but always blows high even when I hit 'off'. Did my new BCM crap out or is this something else? Any thoughts appreciated.

[fastblackmerc]

Last year my vent fan died and a new BCM took care of it. Yesterday the fan got stuck on high, it will switch between def/vent/floor just fine and temp adjust, but always blows high even when I hit 'off'. Did my new BCM crap out or is this something else? Any thoughts appreciated.

Was the BCM a Motorcraft one?

[Sactown]

Was the BCM a Motorcraft one?

Yes. I tend to default to OEM when possible.

[fastblackmerc]

Yes. I tend to default to OEM when possible.

Tap the BCM and see if it changes the blower speed.

[Sactown]

Tap the BCM and see if it changes the blower speed.

Unfortunately no effect. I used to tap the old one to turn it on but the tap won't shut it off

[fastblackmerc]

Try running the EATC self test.

[Sactown]

Try running the EATC self test.

Sorry I should have remembered to do that. Code 051 which per another thread is 051 EATC (Intermittent) Run-Time Fault = A/C Solar radiation sensor open circuit.

Could this wig out the fan?

[fastblackmerc]

Sorry I should have remembered to do that. Code 051 which per another thread is 051 EATC (Intermittent) Run-Time Fault = A/C Solar radiation sensor open circuit.

Could this wig out the fan?

It sure could.

[Sactown]

It sure could.

Cool thanks! Guess I'm gonna pull the dash top and examine it. Perhaps I didn't connect the wires well when I replaced the blend door accuator.

For reference, the service manual page 412-00-31 discusses the test procedures for the solar radiation sensor. Fordparts.com carries the part #19E663 Climate Control Sun Sensor

[Sactown]

A related parts question, per another parts website the full # is F5VY19E663A and is no longer available. I'm wondering if this sensor is the same on many Fords, hard to imagine Ford making this unique to MMs. Any other parts resources out there that shows parts that are the same but with different numbers?

[MyBlackBeasts]

Does it blow on high even when ETAC is in Off setting?

If yes, probably BCM again.

Just went through this myself. Something in BCM circuit board pukes.

The new Motorcraft unit I put in a couple years prior did this. Installed another new Motorcraft BCM from Tasca and all cured.

Good luck with the repair!

[1Marauder]

Cool thanks! Guess I'm gonna pull the dash top and examine it. Perhaps I didn't connect the wires well when I replaced the blend door accuator.

For reference, the service manual page 412-00-31 discusses the test procedures for the solar radiation sensor. Fordparts.com carries the part #19E663 Climate Control Sun Sensor

I want to watch/help!

[Sactown]

Does it blow on high even when ETAC is in Off setting?

If yes, probably BCM again.

Just went through this myself. Something in BCM circuit board pukes.

The new Motorcraft unit I put in a couple years prior did this. Installed another new Motorcraft BCM from Tasca and all cured.

Good luck with the repair!

Yes, blows high even when turned off.

[MyBlackBeasts]

Yes, blows high even when turned off.

If ETAC self test shows ok, easy & cheap 1st.

BCM's are cheap, replace it and see what you get for a result.

Tasca had best pricing when I did it a couple months back.

[Sactown]

So an update: I had a break in the weather and a bit of time and popped off the forward dash cap and sure enough the wiring connector on the solar sensor was loose, my fault from putting it together the last time. So now the EATC test doesn't give any codes which is good. But the fan is still always blowing on high so that didn't solve it.

Any other thoughts before changing the BCM a second time in 6 months?

[Sactown]

So I finally got the warranty replacement BCM from Ford and installed it on Tue and that fixed the problem.

[01BADMERC]

Cool..That's the route I'll be going. Mine is doing the exact same thing. Thanks for sharing!

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[tbone]

With the failure rate of OEM units, I'm surprised more people don't try the aftermarket. I can't remember if I replaced mine with OEM or not about 5 years ago.

[01BADMERC]

Apparently.. The previous owner had it replaced twice within 3 years. From the dealer.

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[tbone]

With all the custom parts people make on here, maybe it's time someone came up with a permanent fix.

[01BADMERC]

I Hear ya..Installed new BCM yesterday and burped system. Good to go!

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[Sactown]

I'm no electrical expert but perhaps the real problem isn't the BCM but some other component causing overload to the BCM, like the fan itself perhaps is pulling too much current. I'd have no idea how to test such a theory.

[fastblackmerc]

I'm no electrical expert but perhaps the real problem isn't the BCM but some other component causing overload to the BCM, like the fan itself perhaps is pulling too much current. I'd have no idea how to test such a theory.

The typical problem with the original Ford BCM is bad / cracked solder joints caused by Fords suppliers using non-lead solder as required by law (RoHS). Since the non-lead solder is more brittle than lead solder the joints crack and stop making contact. Tapping the BCM will usually close the cracked joint. As I stated above, it looks like your BCM was an aftermarket piece. They are notorious for being unreliable (as are the aftermarket Blend Door Actuators). All the Ford BCMs I have repaired with lead solder and and an upgrade have performed flawlessly.

[Sactown]

The typical problem with the original Ford BCM is bad / cracked solder joints caused by Fords suppliers using non-lead solder as required by law (RoHS). Since the non-lead solder is more brittle than lead solder the joints crack and stop making contact. Tapping the BCM will usually close the cracked joint. As I stated above, it looks like your BCM was an aftermarket piece. They are notorious for being unreliable (as are the aftermarket Blend Door Actuators). All the Ford BCMs I have repaired with lead solder and and an upgrade have performed flawlessly.

FTR my parts were all FOMOCO purchased through dealerships