ByPassing "HAL" the A/C Heat Control Module
Hi Scottie,
Love your videos! I have an automatic 2016 Ford Edge SE with 105,000 miles on it. It has been having the A/C Computer problems that seem to be common in these vehicles. I learned from one of your earlier videos how to reset the computer by disconnecting the battery cables and using a little linking wire to connect the cables to drain all the reserve power from the computers. We have been doing that many times, and it works. However, it seems to work for shorter and shorter periods over time. We are down to 1 or 2 days each time now.
We have also taken the car into dealership repair shops 4 times now in that same time, and out of those 4 appointments, one time they found that the computer module was overheating and tripping the system off, but they couldn't figure out why. But they replaced the Gateway Module, and since then, the A/C control would flicker on and off for a few miles, and then remain on, starting the day after they replaced that part. Previously, when it would go off, it would simply stay off until I would use that resetting trick. The other three repair shop visits came up with no info or help.
But now it went off again and is still off.
My question is, if I do the bypass switch and thermostat you show in this video https://youtu.be/ah4OEeCu1KE does that simply allow me to turn the A/C and Heat on and off, completely bypassing the center console controls, or does it work in tandem? If it only works in tandem, what do I do when the center console doesn't power on at all? But if it completely bypasses all controls, does the bypass method allow me to turn from heater to A/C?
Thank you for your help!
Chris
You can't do what Scotty did in that 2007 video.
Things have changed considerably since then.
Back then, the computer would provide a ground to the AC clutch relay to energize it and turn on the AC compressor.
The controls were mostly directly controlled by the HVAC head unit.
The way the computer controls the AC clutch hasn't changed much but everything else has.
For example:
Blower Motor Speed
When blower speed is selected, the FCIM (Front Controls Interface Module) sends the desired blower speed to the HVAC module. The HVAC module then commands the blower motor speed control to the desired speed. The HVAC module monitors the blower motor speed control feedback circuit to make sure the blower motor is at the desired speed.
But the FCIM & HVAC modules do more than that:
Through the FCIM the HVAC module determines the correct conditions for the following outputs:
- A/C compressor operation
- Blower speed
- Temperature blend door position
- Airflow mode door position
- Air inlet door position
It gets even better. Let's say you have an info screen in your vehicle.
When the FDIM touchscreen or IPC steering wheel controls are used, they send a function request message over the Infotainment Controller Area Network (I-CAN) to the FCIM .
The FCIM reads the climate control selections and sends the requests to the HVAC module in the following message path:
- The FCIM sends the requests over the I-CAN to the IPC module.
- The IPC module then relays the requests to Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN) .
- Lastly, the BCM then sends the requests to the HVAC module over the Medium Speed Controller Area Network (MS-CAN)
Here you have 3 networks involved just because you want to blow some warm air on your feet after walking in the snow.
So any malfunctioning module or a short/open in a network's twisted-pair wires can drag the entire network down.
(probably what happened to that guy you mentioned who had No center console control or power, no front windows power, and no front locks power, and blinker sound even goes silent).
The problem is that even though there's a lot of guys who can check power and grounds and read a scanner, it's harder to find a guy who will connect to those networks with a scope and figure out where the problem is. (and they're expensive because they know what they're doing).
In your case there's 3 likely suspects. The Front Controls Interface Module, the HVAC control module, or a short/open in a twisted-pair network wire.
Nobody can diagnose this from 1000 miles away and I'm not trying to do that.
But in your shoes, and considering the hourly rate of a guy who knows how to diagnose this, I'd be inclined to buy a used Front Controls Interface Module (Dash Climate Control Module). You can find them on ebay for $75 to $100 bucks (probably cheaper if you have a local junkyard) and they aren't too hard to swap out.
That's less than a guy would charge for 20 minutes of diagnostic time who knows what he's doing (more or less depending upon where you live).
Don't get me wrong. I'm not telling you that this is the problem and I'm not saying to do this. All I'm saying is that chasing down network issues is a pain if you can do it yourself, and expensive if you can't. I'd gamble $100 and go for the low hanging fruit
My question is, if I do the bypass switch and thermostat you show in this video does that simply allow me to turn the A/C and Heat on and off, completely bypassing the center console controls, or does it work in tandem?
That modification hotwires the compressor clutch so you can turn on the air conditioning manually with a toggle switch despite a malfunctioning HVAC module. It essentially makes your AC compressor operate the way it would have in pre-computer vehicles.
Plusbig problem is that all this does is operate the compressor. It won't help if your blend door, vent flaps, or cabin fan are not working properly. It also will not operate the heat.
Another possible issue is that some newer cars don't have a compressor clutch. Instead they use a control valve operated by the computer. Obviously this hack won't work on that kind of setup.
Thank you Chuck! That helps! 🙂
Does anyone have any ideas about how to actually fix the issue we are having with our 2016 Ford Edge A/C and Heat? So far, the Ford Dealerships can't seem to find a definitive answer. And in all of the forums I have searched, the closest answer I have found is that someone found an electrical short in their car that was doing the same thing (No center console control or power, no front windows power, and no front locks power, and blinker sound even goes silent). When I suggested the electrical short idea to the dealer repair shop, they found only one wire that might have been an issue after taking the car panels and everything apart. But we were right back to square one the day after driving it away from the shop again.