2010 Ford Fusion HVAC Problems

[RomanChariot]

Shippy may be the only one able to help me with this problem but I'll take help from anyone.

My daughter has a 2010 Ford Fusion S with manual HVAC. Earlier this summer her car had a problem with the AC blowing warm because of a bad evaporator temperature sensor. To replace the sensor you have to remove the entire dash. I did not have time to do that so I found a work around online and pulled the two wires from the connector behind the glove box that go to the sensor and hooked them up to a resistor. That worked fine to get the AC working but she lost the ability to get heat and she also lost the ability to change modes from vent to defrost or feet etc.. When she did not need AC anymore, I reconnected the wires but the other functionality did not return.

I have tried replacing the blend door motor because those are known to have problems but that did not help. I finally figured that because both the heat settings and the mode settings were not working it must be the HVAC control module. I took the time to tear the dash apart and replace the defective temp sensor. I have put another used HVAC module in and it is still not working. The fan control on the module works and the mode buttons light up when you push them but nothing changes. The rear defrost button won't light up on either module and the AC is not coming on but the button lights up.

At this point I don't know if I have just had 2 bad HVAC modules or if the smart junction box might be bad. I have checked all of the fuses that have to do with the HVAC. I can't find schematic of the system. Anyone have any other suggestions?

[shp4man]

This system is all electronic control, and in order to get an accurate diagnosis, a scan tool able to test codes and display various HVAC sensors operation and voltages will be needed. Best option may be just bite the bullet, take it to a Ford dealer, make sure the service advisor gets the whole story down accurately for the tech. They may charge $130-$230 just to figure out the problem. Sorry.
Sounds like the workaround may have damaged something, but that's just a guess.

[RomanChariot]

Yeah, I figured I would probably have to take it in. The timing makes it seem that the workaround could have damaged something although I don't see how. The faulty part was just a thermistor which is just a temperature sensitive resistor. It's not like you can hook it up backward.

[shp4man]

There are more than one actuator in that system. If one of them isn't working, it should latch a code in the HVAC module. But the inoperative A/C switch tells me there are other issues besides the mode door not working.

[RomanChariot]

Can you tell me if the mode door motor is the same as the blend door motor? I bought a new blend door motor but it did not fix the problem with not being able to adjust the temperature. Since I had the dash apart I moved the motor to the location that controls the mode door (just above the blend door motor) since it is not accessible with the dash in place. The motor for both locations looks identical but I cannot find any information on the mode door motor anywhere.

[shp4man]

Looks like it has 3 actuators, mode door, temp and recirculation door. Check fuse 15/10amp(red) in the body control module/inside fuse box. That powers the HVAC module.

Need a VIN to look up parts.

[RomanChariot]

I don't have the VIN on me. I have checked fuse 15 and it is fine.

[shp4man]

Check the connectors that were disconnected when the dash came off.

[RomanChariot]

I'll do that although these problems existed before the dash came off. I'll post the VIN number later if you don't mind checking to see if the mode door and blend door actuators are the same since I can't find that information. I think the recirculation actuator is different.

[shp4man]

I'll do that although these problems existed before the dash came off. I'll post the VIN number later if you don't mind checking to see if the mode door and blend door actuators are the same since I can't find that information. I think the recirculation actuator is different.

OK

[RomanChariot]

The VIN number is 3FAHP0GA8AR244421.

Would a ELM327 scan cable and Forscan be able to see where the issue might be?

[shp4man]

The Ford service info server is down. Looks like they could use some better IT people at Ford. 

[shp4man]

According to the parts catalog, the top actuator on the drivers side is an AE5Z-19A817-AA or AB. The lower one, mounted right under it, is an AE5H-19E616-AA or AB. These are the numbers printed on the actual part, called engineering numbers. The actual service part number is different. Confusing? Yep. That's Ford. So the 2 actuators on the drivers side are different.
I don't know for sure if Forscan can do it, but it can pull HVAC codes, I think.  Pull the codes.

[RomanChariot]

Thanks. That is really helpful.

[RomanChariot]

I finally go some time to scan the car using Forscan. Here are the DTCs for the HVAC module.

Code: B11E7 - Air Distribution Damper Position Sensor

Additional Fault Symptom:
- Circuit Short To Battery Or Open
Code: B11E5 - Left HVAC Damper Position Sensor

Additional Fault Symptom:
- Circuit Short To Battery Or Open

Code: B1086 - Air Distribution Damper Motor

Additional Fault Symptom:
- Circuit Open

Code: B1081 - Left Temperature Damper Motor

Additional Fault Symptom:
- Circuit Open

Forscan also shows the evap temperature sensor reading a temperature of -38 degrees Celsius. However when I measure the resistance on the evap temperature sensor with on ohm meter it shows 40kohms which should equate to around 15-20 degrees Celsius which would match the local weather. This tells me that the new sensor I put in is working but something is wrong with the way the car is interpreting the signal.

With Forscan I can see when each of the buttons on the HVAC controller are pushed so it seems that the controller is working but there is no communication between the controller and the actuators. Do you know if this signal goes through the smart junction box or does it go straight from the HVAC controller to the actuators?

[RomanChariot]

There was one other HVAC DTC as follows.

Code: U0423 - Invalid Data Received From IPC

Additional Fault Symptom:
- Event Information

I did not think it significant as it was listed as being previously set but not present at the time of testing. However, there was another DTC for the IPC that was present as follows.

Code: U0011 - Medium Speed CAN Communication Bus Performance

Additional Fault Symptom:
- Bus Off

I don't know if that is significant but it could be.

[shp4man]

It sounds like you have a connector that's not connected or not "clicked" in. I'm not at work right now, so I'll check it out Monday.

[RomanChariot]

I really seems like there is a missing electrical connection. I have checked all of the connections that I can think of at the actuators and the HVAC control module as well as behind the glove box. I can't find a good diagram of the HVAC system to know where else the wiring goes.

[shp4man]

OK, open or remove the glove box, there are 2 connectors behind it on the lower rail. Check both of those.

[RomanChariot]

I have checked to see that both of those are tight. I pulled the 2 wires that go to the thermistor from one of those connectors to jump them with a resistor in order to get the AC working. I believe that I got them back correctly but I will check that tonight to make sure that they are making a proper connection.

[shp4man]

Look for pushed out pins by inspecting both male and female connectors.

[RomanChariot]

I'll do that. If that turns out to be the problem I'll have to kick myself really hard.

[RomanChariot]

Car is finally working properly again. After scanning the car and running a series of continuity testing on the wires it turns out that there was an open in the Vref Return wire. As near as I can tell it was in a wire that runs along the firewall and communicates the position of both the blend door actuator and the mode actuator. I really did not want to pull the entire dash out to try and find the open so with a little testing I was able to determine that I could cut the wire near the 2 actuators and splice in a new wire from there to the HVAC control module.

[shp4man]

Car is finally working properly again. After scanning the car and running a series of continuity testing on the wires it turns out that there was an open in the Vref Return wire. As near as I can tell it was in a wire that runs along the firewall and communicates the position of both the blend door actuator and the mode actuator. I really did not want to pull the entire dash out to try and find the open so with a little testing I was able to determine that I could cut the wire near the 2 actuators and splice in a new wire from there to the HVAC control module.

Nice, well done! 

[RomanChariot]

Nice, well done! 

Thank you for your help. The Forscan software worked really well. I have not gone through all of its capabilities but it allowed me to see every button push on the HVAC module as well as all of the sensor readings. It was easy to pull up all of the DTCs. Pretty nice for a free software combined with a $30 adapter.

[shp4man]

Thank you for your help. The Forscan software worked really well. I have not gone through all of its capabilities but it allowed me to see every button push on the HVAC module as well as all of the sensor readings. It was easy to pull up all of the DTCs. Pretty nice for a free software combined with a $30 adapter.

Which adapter are you using?

[RomanChariot]

Which adapter are you using?

I got this adapter from Amazon.

http://amzn.to/2mum6z5