Cabin Fan Problem
08-08-2011, 10:35 AM
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Cabin Fan Problem
Hi
I did several searches using the keywords that make sense to me, and found nothing about the problem with my '07 F150 super Crew.
I thought I had an after market service manual, but I guess not and I'll have to get one.
The other day, I noticed that the cabin blower works fine on speeds 1, 2 & 4 but while on speed 3, it blows the same as speed 2.
Based on some of what I read, it seems the different speeds simply switch between different series resistors. That being said, unless the speed-3 resistor increased to a similar value as speed-2 (which seems a bit unlikely) I'm a bit confused about this malfunction.
Also, where might I find this speed control board?
Any help would be appreciated..
Thanx
I did several searches using the keywords that make sense to me, and found nothing about the problem with my '07 F150 super Crew.
I thought I had an after market service manual, but I guess not and I'll have to get one.
The other day, I noticed that the cabin blower works fine on speeds 1, 2 & 4 but while on speed 3, it blows the same as speed 2.
Based on some of what I read, it seems the different speeds simply switch between different series resistors. That being said, unless the speed-3 resistor increased to a similar value as speed-2 (which seems a bit unlikely) I'm a bit confused about this malfunction.
Also, where might I find this speed control board?
Any help would be appreciated..
Thanx
08-08-2011, 01:46 PM
#2
Moderator (Ret.)
Kudos for searching!
It could be the fan switch itself (assuming you have the fan speed switch control and not the "auto climate" feature).
There is a fan resistor located behind the glove box door. Open the glove box, then press in the sides toward the upper left/right of the inner glove box door, this allows it to drop down. You should then see the fan resistor. Assuming this is the problem, it's a cheap part and easy (under 20 bucks) to buy and replace.
This resistor though usually fails and does not allow the higher speeds to work. Your failure has to do with speed 2 and 3 being the same, which does not seem to be this resistors fail symptoms.
If it's the fan switch itself, it's part of a circuit board that also contains the temp control switch, and the vent control switch (again, assuming you have the non "auto climate" feature), the AC on/off switch, and some other on/off switches like rear window/outside mirror defrost. I do not think these switches are replaced individually. I have one of these assemblies that had the vent control switch go bad; I went to a junkyard and bought one. I examined this assembly, and it does not look like the individual switches are made to come off easily. Perhaps they can be soldered off and on. If you want to attempt that, I can send you my assembly (the vent switch circuit does not switch between floor/dash vent/defrost) and you can try to remove the fan switch (it worked). PM me if you want to go that route.
No charge of course for the assembly.
It could be the fan switch itself (assuming you have the fan speed switch control and not the "auto climate" feature).
There is a fan resistor located behind the glove box door. Open the glove box, then press in the sides toward the upper left/right of the inner glove box door, this allows it to drop down. You should then see the fan resistor. Assuming this is the problem, it's a cheap part and easy (under 20 bucks) to buy and replace.
This resistor though usually fails and does not allow the higher speeds to work. Your failure has to do with speed 2 and 3 being the same, which does not seem to be this resistors fail symptoms.
If it's the fan switch itself, it's part of a circuit board that also contains the temp control switch, and the vent control switch (again, assuming you have the non "auto climate" feature), the AC on/off switch, and some other on/off switches like rear window/outside mirror defrost. I do not think these switches are replaced individually. I have one of these assemblies that had the vent control switch go bad; I went to a junkyard and bought one. I examined this assembly, and it does not look like the individual switches are made to come off easily. Perhaps they can be soldered off and on. If you want to attempt that, I can send you my assembly (the vent switch circuit does not switch between floor/dash vent/defrost) and you can try to remove the fan switch (it worked). PM me if you want to go that route.
No charge of course for the assembly.
Last edited by Mod (Ret.); 08-08-2011 at 01:56 PM.
08-08-2011, 03:40 PM
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Kudos for searching!
It could be the fan switch itself (assuming you have the fan speed switch control and not the "auto climate" feature).
There is a fan resistor located behind the glove box door. Open the glove box, then press in the sides toward the upper left/right of the inner glove box door, this allows it to drop down. You should then see the fan resistor. Assuming this is the problem, it's a cheap part and easy (under 20 bucks) to buy and replace.
This resistor though usually fails and does not allow the higher speeds to work. Your failure has to do with speed 2 and 3 being the same, which does not seem to be this resistors fail symptoms.
If it's the fan switch itself, it's part of a circuit board that also contains the temp control switch, and the vent control switch (again, assuming you have the non "auto climate" feature), the AC on/off switch, and some other on/off switches like rear window/outside mirror defrost. I do not think these switches are replaced individually. I have one of these assemblies that had the vent control switch go bad; I went to a junkyard and bought one. I examined this assembly, and it does not look like the individual switches are made to come off easily. Perhaps they can be soldered off and on. If you want to attempt that, I can send you my assembly (the vent switch circuit does not switch between floor/dash vent/defrost) and you can try to remove the fan switch (it worked). PM me if you want to go that route.
No charge of course for the assembly.
It could be the fan switch itself (assuming you have the fan speed switch control and not the "auto climate" feature).
There is a fan resistor located behind the glove box door. Open the glove box, then press in the sides toward the upper left/right of the inner glove box door, this allows it to drop down. You should then see the fan resistor. Assuming this is the problem, it's a cheap part and easy (under 20 bucks) to buy and replace.
This resistor though usually fails and does not allow the higher speeds to work. Your failure has to do with speed 2 and 3 being the same, which does not seem to be this resistors fail symptoms.
If it's the fan switch itself, it's part of a circuit board that also contains the temp control switch, and the vent control switch (again, assuming you have the non "auto climate" feature), the AC on/off switch, and some other on/off switches like rear window/outside mirror defrost. I do not think these switches are replaced individually. I have one of these assemblies that had the vent control switch go bad; I went to a junkyard and bought one. I examined this assembly, and it does not look like the individual switches are made to come off easily. Perhaps they can be soldered off and on. If you want to attempt that, I can send you my assembly (the vent switch circuit does not switch between floor/dash vent/defrost) and you can try to remove the fan switch (it worked). PM me if you want to go that route.
No charge of course for the assembly.
On a side note, the only two ways that I can explain the failure is if the speed-3 resistor opened and the speed-2 and speed-3 wires were shorted (seems unlikely) or if the switch skips 3 and maintains contact with #2 which I also don't understand. I obviously need to do some digging, just wanted to check and see if anyone else had heard of such a thing and prevent me from re-inventing the wheel.
Let me get that manual, figure out how to open that control panel and perform some measurements. Is the control panel difficult to remove? I'm an old car kinda gay and haven't done a bunch of work on these new ones. I'll report back about my finding..
08-08-2011, 04:01 PM
#6
Moderator (Ret.)
To get at the panel, remove the radio/AC control surround trim panel. This is easily done by pulling at the top or bottom corners to release the snaps, then slide your left and right fingers along the sides of this trim panel up and pull out. Then remove the "passenger seat warning" wire harness, the right lower side panel harness (has a tab that needs to be slid up; it has a center lock tab that needs to be pushed, then slide the grey tab up), then remove the cigarette wire harness.
4 screws are then removed to remove this AC assembly circuit (with the switches) from the trim panel. As to removing the switches themselves, I've not done that. I just replaced this assembly with one a bought for 20 bucks at a junk yard.
4 screws are then removed to remove this AC assembly circuit (with the switches) from the trim panel. As to removing the switches themselves, I've not done that. I just replaced this assembly with one a bought for 20 bucks at a junk yard.
Last edited by Mod (Ret.); 08-08-2011 at 04:04 PM.
08-08-2011, 04:46 PM
#7
Senior Member
Dangit...I have this problem and I just noticed it within the last month or so! I do notice that if I gently turn it one way or the other while still in the "3" indent, it will change back to the proper speed.
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08-09-2011, 01:35 AM
#8
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I hit three different auto parts stores and their computers suggest a haynes manual. That particular haynes manual only covers pickups to 2003 and expeditions to 2009.
Am I missing something?
Thanx dude, much appreciated.
Am I missing something?
To get at the panel, remove the radio/AC control surround trim panel. This is easily done by pulling at the top or bottom corners to release the snaps, then slide your left and right fingers along the sides of this trim panel up and pull out. Then remove the "passenger seat warning" wire harness, the right lower side panel harness (has a tab that needs to be slid up; it has a center lock tab that needs to be pushed, then slide the grey tab up), then remove the cigarette wire harness.
4 screws are then removed to remove this AC assembly circuit (with the switches) from the trim panel. As to removing the switches themselves, I've not done that. I just replaced this assembly with one a bought for 20 bucks at a junk yard.
4 screws are then removed to remove this AC assembly circuit (with the switches) from the trim panel. As to removing the switches themselves, I've not done that. I just replaced this assembly with one a bought for 20 bucks at a junk yard.
08-29-2011, 12:56 AM
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Couple other things:
1) Seems the resistor board is dealer only, Napa didn't stock it.
2) Picking up trim removal tools from a harbor freight REALLY makes the job much easier and does not damage the interior. Only $6.50 for a 4-piece tool set.