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Rear AC Blower Not Working

40K views 39 replies 14 participants last post by  Paulo 
#1 ·
So a few weeks ago I lost the rear AC in my 2016 Transit 15 passenger 350 XLT.

The heat in this van only blows out of the top vents, and the AC blows from the bottom vents. It was this way since we purchased it, and I believe is the intended design. If I turn the heat on, the blower cuts on and air comes out of the vents in the roof. If I turn the rear AC on, nothing happens and you feel nothing from the floor or roof vents.

I have checked the rear blower fuse and relay and both are GOOD to go. What should I check next?
 
#2 ·
Should be the opposite of what you are saying

Randall,

Owners manual, page 93, indicates the opposite. Mine operates the same as the owners manual - AC from roof vents and heat from floor.
Do you have dash and overhead rear controls both set the same ?
If you are getting heat from the roof, maybe you need to have freon checked.

Good Luck

Semper Fi
 
#5 ·
Did it all of a sudden stop blowing? Also, is the front AC on when you try to turn on the rear?

You mentioned checking fuses/relays:
F23/7.5a Air conditioning control module
F38/5a blower motor relay
F41/40a rear blower motor
R10 rear blower relay
 
#8 ·
Randall,

You should hear the rear heat motor noise from around the front passenger seat (it's under there ) If you turn on the rear AC and hear nothing at all, you have a problem with your motor. Even if your freon was low or out you should hear the motor from the right rear drivers side blowing warm air through the overhead vents.

Semper Fi
 
#11 ·
So, I have checked the connections, relays and fuses. I swapped the rear relay with the front relay and the front works fine...

I have checked the return for debris and it could be cleaned but it wasn't bad.

The fan motor has no power going to it. I checked at the harness. With the relays being good and the fuses all fine, should I check the actual overhead dash switch? That's the only thing I can think of at this point unless there is a fuse or SOMETHING somewhere else I should check?
 
#12 ·
With the relays being good and the fuses all fine, should I check the actual overhead dash switch
That wouldn't hurt, does the rear fan speed switch change the heater blower speed?
Does the rear temp blend switch seem to move properly?

Sounds like you've gone through good troubleshooting procedures.
 
#13 ·
I do have power to the rear fan motor but I don't know how much. Test light shows power though, on both sides of the terminal (wire harness on fan motor). One side is significantly brighter than the other, meaning more power I assume. I have tried a brand new fan and that didn't do anything. Maybe the PWM? I don't know how to test any of that. I'm stuck at this point. The only thing I can think of now is either the interior switch or the PWM.

The interior switch does indeed work and adjust fan speed for HEAT, and it does seem to blend or at least adjust the flow when setting the temp in the "white" zone which is a blend of hot and cool.
 
#14 ·
To be able to check certain PWM/Canbus signals, you can use a logic probe which is more helpful than a voltmeter in many circuits.
 

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#15 ·
Tried a new fan motor, nothing.

Tried a new rear blower motor fan resistor, nothing.

I have no idea what is left to check besides the controls in the roof/dashboard.

Anybody have any ideas or thought? Remember I checked the relay for the rear by switching it with the front systems relay... front worked fine either way.

Yes, the dash controls control the heat and fan speed perfectly. Is there something else I should be trying?

Do the wires for that part of the system run under the seats? Maybe it's wet or something?
 
#17 ·
@Randall Steele Smith


Where you able to find resolution for this issue?


My 2 month old Transit is having issues with the rear blower also. When I turn on the switch the blower will run for a little bit and then it turns off. Doesn't matter what fan speed is selected. If I rotate the switch to zero and then back to any speed it will blow again for a little while and then completely stop. The timing of the shut-off is not consistent and it will exhibit the same behavior on a hot day or a cool morning.

Anyone experience something similar?

My searches have mostly brought up A/C not working efficiently or at all. Front AC for me is still functional.
 
#18 ·
Was the blower fan you swapped in a OEM ???
Bench test the fan before you swap it in by applying 12 volts from a power supply or battery ,
I bought 2 cheap fans from online , neither one of them worked , I then swapped in a $110 OEM fan from the Ford dealership and it has been working ever since.
My original fan that came with my van burned up , it was my fault for turning it on and off real fast multiple times , long story ,, I was doing some testing with temp sensors all over the place while building a custom heater system.
I now have a really trick front and rear heater system.
 
#21 ·
get a shop manual and follow the troubleshooting steps, step-by-step and you will find the core root issue without replacing parts. You will run out of money replacing parts before finding the culprit.

here is 72 hour access to the factory electronic service manual for 21.95 https://www.motorcraftservice.com/Purchase/ViewProduct
 
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