A/C not working

[kevn]

Car was blowing ice cold air, after turning the car off and then turned it on, the A/C was not working anymore and the button showed as on but no air flow. Tried different fan speed and even tried the heater but nothing blows.
With a scanner it was giving me a short circuit on the blower motor relay, swapped it out and clear the code but came back immediately and nothing changed. Blower motor is not getting 12v, checked at the fuse box, slot 4 for the blower motor and the relay is no getting 12 v either when the a/c is on. Checking all the fuses under de relays and under the steering wheel all look good.
To note: the compressor doesn't engage either.
Fault code: b10af:15:0a

Sponsored

 

[Stevedbvik1]

Car was blowing ice cold air, after turning the car off and then turned it on, the A/C was not working anymore and the button showed as on but no air flow. Tried different fan speed and even tried the heater but nothing blows.
With a scanner it was giving me a short circuit on the blower motor relay, swapped it out and clear the code but came back immediately and nothing changed. Blower motor is not getting 12v, checked at the fuse box, slot 4 for the blower motor and the relay is no getting 12 v either when the a/c is on. Checking all the fuses under de relays and under the steering wheel all look good.
To note: the compressor doesn't engage either.
Fault code: b10af:15:0a

https://www.ranger5g.com/forum/threads/blower-motor-quit-working.26174/

 

[RangerBill]

Car was blowing ice cold air, after turning the car off and then turned it on, the A/C was not working anymore and the button showed as on but no air flow. Tried different fan speed and even tried the heater but nothing blows.
With a scanner it was giving me a short circuit on the blower motor relay, swapped it out and clear the code but came back immediately and nothing changed. Blower motor is not getting 12v, checked at the fuse box, slot 4 for the blower motor and the relay is no getting 12 v either when the a/c is on. Checking all the fuses under de relays and under the steering wheel all look good.
To note: the compressor doesn't engage either.
Fault code: b10af:15:0a

It could be that there is a problem in the battery junction box (BJB). The blower motor relay is located in the BJB and is non-serviceable. The fault code is referencing the coil side of the blower relay. It could be wiring between the FCIM and the BJB.

From the shop manual:

FCIM B10AF:15
Blower Fan Relay: Circuit Short To Battery Or Open Module senses greater than expected voltage on the blower relay coil voltage circuit, indicating an open circuit or a short to voltage. The blower motor relay is inactive when circuit is open; the blower motor relay is on all the time when shorted to battery.



Possible Sources

• Fuse
• Wiring, terminals or connectors
• Blower motor relay (non-serviceable, part of the BJB )
• Blower motor
• Blower motor control module
• FCIM

Visual Inspection and Pre-checks

• Make sure BJB fuse 79 (40A) is OK.

 

[airline tech]

For Ref - Fuse 79 is on the bottom side of the BJB - you must remove the BJB to get access to the bottom side of it
and this is one of the manuals not matching actual layouts
The - Blower Motor Relay - is a - Serviceable Relay

Also note that the Blower Motor Control Module is incorporated into the blower motor itself - its all in one unit and not separate as the wiring g diagram depicts

The FCIM controls the (relay coil power) and it also is a controlled motor (varying ground) for the motor speed - so the FCIM is the primary control for it.

FCIM - feeds relay coil power
BJB - Fuse 79 - feeds the blower motor power but the FCIM controls the ground for it - this is how it varies the motor speed.

Circled = Blower Motor Relay

Fuse 79 - Location

 

[RangerBill]

Another mistake in the shop manual.

 

[kevn]

For Ref - Fuse 79 is on the bottom side of the BJB - you must remove the BJB to get access to the bottom side of it
and this is one of the manuals not matching actual layouts
The - Blower Motor Relay - is a - Serviceable Relay

Also note that the Blower Motor Control Module is incorporated into the blower motor itself - its all in one unit and not separate as the wiring g diagram depicts

The FCIM controls the (relay coil power) and it also is a controlled motor (varying ground) for the motor speed - so the FCIM is the primary control for it.

FCIM - feeds relay coil power
BJB - Fuse 79 - feeds the blower motor power but the FCIM controls the ground for it - this is how it varies the motor speed.

Circled = Blower Motor Relay

Fuse 79 - Location

 

[kevn]

The fuse on the back of the BJB, 40A fuse looked okay, I swapped it around with another one that also is 40A and nothing changed.

Relay slot 4, blower motor was replaced as well and same issue.

Since I'm not getting power on the blower motor relay pin 1 and 2 when I have the A/C "on", have any of you tried feeding the blower motor 12V to check if it's working? And if that works that would indicate a problem on the BJB?

 

[RangerBill]

The fuse on the back of the BJB, 40A fuse looked okay, I swapped it around with another one that also is 40A and nothing changed.

Relay slot 4, blower motor was replaced as well and same issue.

Since I'm not getting power on the blower motor relay pin 1 and 2 when I have the A/C "on", have any of you tried feeding the blower motor 12V to check if it's working? And if that works that would indicate a problem on the BJB?

Pin 1 should go to ground. Check with an ohmmeter from pin 1 to a ground on the truck body. When you are checking for voltage to pin 2, are you using a body ground connection for the meter negative connection?

When you swapped relays for the blower motor relay, did you make sure that they both had the same part number? I believe that there are 2 different relays in the BJB that will fit in the sockets, but don't have the same contacts and won't interchange, even though they look the same.

 

[RangerBill]

The blower motor module has a fixed ground, the FCIM sends a pulse width modulated (PWM) speed command reference to control the fan speed. It is not a varying ground to the motor.

 

[airline tech]

Yes and No - The diagram does not show (The Motor) it only shows the (Module) the module itself has a constant ground - but to vary the motor speed, the PWM signal opens and closes the (applied ground)

Estimated duty cycle (ref only)

LOW - Duty Cycle = 25% - Fan Operation is - On-Off-Off-Off - means the ground is applied 25% of the time

MEDIUM - Duty Cycle = 50% - Fan Operation is - On-Off-On-Off - means the ground is applied 50% of the time.

So yes the module is constant ground but for motor speed its (varying) the time it receives ground via the (Ground Side Controlled) PWM Signal by doing this it varies the voltage the motor is receiving
an example would be
25% - Duty Cycle - would read about 3 volts
50% - Duty Cycle -would read about 6 volts

Note: In the diagram - the dashed line between (PWM and Ground)

 

[airline tech]

The fuse on the back of the BJB, 40A fuse looked okay, I swapped it around with another one that also is 40A and nothing changed.

Relay slot 4, blower motor was replaced as well and same issue.

Since I'm not getting power on the blower motor relay pin 1 and 2 when I have the A/C "on", have any of you tried feeding the blower motor 12V to check if it's working? And if that works that would indicate a problem on the BJB?

i do not have a (pic) pinout for the 4 pin relays (yet) but here is one for the 5-pin as an example
are you getting 12-volt power on any pin - one should be constant power from fuse 79
when the FCIM applies power on the coil - if the relay is installed it will allow that fused power down to the motor via the coil (closing) the relay
The coil side -power may be 5-volts or so, not a full 12 as it is FCIM module output.
for ref - the larger blades are the motor power feeds and pin 3 should have a constant 12 volts

 

[kevn]

Looking at the diagram on the relay:

Pin 1 goes to ground
Pin 2 gets the signal form the FCIM

Pin 3 is hot all the time
Pin 5 connects to the blower motor.

When I checked for voltage on the relay, I checked on pin 1 and 2, I haven't tried chassis ground to pin 3.

Since the indicator lights are turning on the dashboard I thought the circuit for pin 1&2 was closed when I had the power button on.

Thanks for all the help so far.

 

[RangerBill]

Looking at the diagram on the relay:

Pin 1 goes to ground
Pin 2 gets the signal form the FCIM

Pin 3 is hot all the time
Pin 5 connects to the blower motor.

When I checked for voltage on the relay, I checked on pin 1 and 2, I haven't tried chassis ground to pin 3.

Since the indicator lights are turning on the dashboard I thought the circuit for pin 1&2 was closed when I had the power button on.

Thanks for all the help so far.

Have you verified that pin 1 of the relay actually goes to ground with an ohmmeter? I would check that out. Then check to see if you have a DC voltage applied to pin 2 when the fan motor should be running. When you substituted the relay, did you verify that it was the correct part number? There are more than one part number relays in that box that will fit, but will not work.

 

[RangerBill]

The coil voltage of the relay is rated 12 volts DC. So, there should be 12 volts DC on the relay coil coming from the FCIM to close the blower relay.
https://www.amazon.com/dp/B0DJZ7R6XZ?lv=shuf&channelId=500&plpRedirect=mhFallback

 

[ControlNode]

For Ref - Fuse 79 is on the bottom side of the BJB - you must remove the BJB to get access to the bottom side of it
and this is one of the manuals not matching actual layouts
The - Blower Motor Relay - is a - Serviceable Relay

Also note that the Blower Motor Control Module is incorporated into the blower motor itself - its all in one unit and not separate as the wiring g diagram depicts

The FCIM controls the (relay coil power) and it also is a controlled motor (varying ground) for the motor speed - so the FCIM is the primary control for it.

FCIM - feeds relay coil power
BJB - Fuse 79 - feeds the blower motor power but the FCIM controls the ground for it - this is how it varies the motor speed.

Circled = Blower Motor Relay

Fuse 79 - Location

Another mistake in the shop manual.

Is it possible that Ford found a problem with the box design for how the pin for the blower relay is secured in the box and the "cheap and CYA fix" was to install the relay before the box is fully assembled, where they can place it on a jig that holds the pins in place while installing that relay and the then ship with that relay preinstalled while updating the manuals to indicate it as non-serviceable, because that whole effort was cheaper than fixing the box design and replacing existing boxes? It could be that if they listed that as serviceable relay and the pin still happens to make enough contact to work, but too little for a good current flow that it becomes a heat/fire concern that would result in mandatory recalls. But if someone services a part they state was non-serviceable it was owner/tech caused safety issue rather than their own.

Sponsored