Hvac issues!!

[Jingram1083]

So first, the front fan, which is dual climate control stopped working. Wiggles the blower motor resistor harness and it worked for a short period. So I then changed the harness. Still wouldn’t work, and if it did, only on high. So I changed the blower motor resistor. Now it works on low, and on high, but on speeds in between it fluctuates intermittently up and down with speed.

second, I have heat and a/c up front, but no heat in the back. Checked the lines that run under the truck to the back. There are 4. 3 big, 1 small. The 2 outside big lines are hot, and the other 2 are cold after running vehicle. Kinda lost at this point. Just want heat in the rear, and my damn fan to work on the setting I choose lol.

 

[jeff kushner]

you might want to post yr and mdl so folks know what you have.

jeff

 

[JExpedition07]

I presume you replaced the plug harness and BCM (Blower Control Module). Dual Zone Climate doesn’t utilize a resistor that is only for manual systems. I had the fan working intermittently/fluctuating and replaced those two parts as well with no relief. Ended up being the blower motor itself that needed replacing then all was well. Next time the fan goes out tap the fan motor itself and see if it turns back on. Blower cage is up under glovebox right front all the way forward. This is how I figured out mine was wonky.....it would die then I could tap the fan housing and it would restart.

Heat will only come out the floor vents on the rear system on these trucks, no heat out of the overhead vents. Heat comes out floor and A/C comes out overhead in rear.

 

[aagitch]

What years does heat only come out of floor for rear? On my 17 I can get heat to come out of the overhead vents if using the rear controls.

 

[Dustin Gebhardt]

What years does heat only come out of floor for rear? On my 17 I can get heat to come out of the overhead vents if using the rear controls.

My '07 is heat only on the bottom and cool only out of the top. I found this out this weekend while doing multiple projects: I replaced the ABS pump, replaced the heater hose (the one for the front heater core from the front/top of the engine), replaced the rear blower fan, and replaced 8 spark plugs. 8 hours later, when everything was mostly buttoned back up, I turned the Expy on and turned the heat all the way up, front and back, and fans set to full blast, to test for leaks from the new heater hose and to test the the rear blower. I could hear the new blower running, but I couldn't feel any air coming from the top vents. It took a few seconds for my weary brain to make the logical connection between the temperature setting and which vents were used. I moved the rear temperature from max-heat to max-cool and the top vents began to push air.

 

[JExpedition07]

My '07 is heat only on the bottom and cool only out of the top. I found this out this weekend while doing multiple projects: I replaced the ABS pump, replaced the heater hose (the one for the front heater core from the front/top of the engine), replaced the rear blower fan, and replaced 8 spark plugs. 8 hours later, when everything was mostly buttoned back up, I turned the Expy on and turned the heat all the way up, front and back, and fans set to full blast, to test for leaks from the new heater hose and to test the the rear blower. I could hear the new blower running, but I couldn't feel any air coming from the top vents. It took a few seconds for my weary brain to make the logical connection between the temperature setting and which vents were used. I moved the rear temperature from max-heat to max-cool and the top vents began to push air.

They set this up because it’s much more efficient to heat from the floor, and cool from the headliner. Heat rises and cool air falls. Same reason when your truck switches to heat in fall it starts coming out the floor and defrost vents instead of the mains like it does during summer months. If heating from the headliner much of it is lost by conduction through the non-insulated roof and the floor goes cold. Ford just set it up so people don’t have to think about it lol.

 

[Mmart]

I too just realized recently that the rear heat zone only comes from the floor (thanks to this forum). But besides that when the truck sits in the cold nine out of ten times I need to tap under the glove box to get the fan running. I just want to be sure is that the fan motor itself? Or is it the wiring harness under there that normally causes this. I haven’t dug into this issue yet. And for the record I have a 2010 EB
Thanks

 

[jcmeyer5]

2015 Expedition here... same, no blower function. Climate control with dual zones. Havent tried tapping the motor yet. Anything else I can check?

 

[Muddy Bean]

2015 EL limited. I can confirm that we can choose to put heat out of ceiling vents and it’s nice.


Second, yes if you blower is turning off and on, give the housing under the dash a good whack. If it comes back on, replace the blower fan.


Sent from my iPhone using Tapatalk Pro

 

[07navi]

I too just realized recently that the rear heat zone only comes from the floor (thanks to this forum). But besides that when the truck sits in the cold nine out of ten times I need to tap under the glove box to get the fan running. I just want to be sure is that the fan motor itself? Or is it the wiring harness under there that normally causes this. I haven’t dug into this issue yet. And for the record I have a 2010 EB
Thanks

dig into it