Delcaring an Emergency! Smoke in the Cabin!

[chefduane]

So yesterday here in Texas it was around 90 degrees. A normal October day.
As I am driving to work, I turn on the AC. Within seconds I smell something distinctly like an electrical fire or short of some kind. Within a few more seconds I recognize that the cabin in filling up with smoke!! Now, one of my pastimes other than cooking is flying, so I am PARTICULARLY ATTUNED to smoke in the cabin!!! ANY CABIN!! Training kicks in and I immediately ventilate the cabin and turn off all electricals (in that order.) Radio off, HVAC off, and I have a dashcam and UltraGuage that I powered down/disconnect. The smoke clears and other than that, the vehicle is performing fine. I get to my destination with no other issues. Car runs fine, but I do not power up any electricals. I continue to my destination and do a complete systems check. Radio/Stereo/Speakers/Antenna all functioning fine. UltraGuage and dashcam function fine. Auxiliary lights (KC 130W HiLites on Westin Safari Bar) functioning fine. Door locks/windows up&down fine, horn fine, etc. No smoke or smell on those items.
All is well, BUT I note that I now no longer have any heat or AC. The blower blowers fine and I can cycle through the fan settings, but I get no heat when the heater is selected, nor cold in AC mode. I get no more smoke or electrical smell either. Also, vent mode settings work fine. The mode selector switch still switches between Dash Vents, Leg Vents, Combo, Defrost, etc. But the natural assumption is a HVAC electrical malfunction.

Could this be the infamous blend door issue? Is smoke in the cabin how this problem manifests itself? (YIKES!!) Certainly some type of electrical issue connected to HVAC. Is the door electrically actuated?
I have not yet had the time to go through all cabin fuses in depth. I did pull the fuse door and gave it a quick sight check and didn't see anything unusual but a closer inspection is clearly needed.

Anybody got any other suggestions?

Chef Duane
(who is glad he was on the ground when this happened, and thank you all for letting me vent. heh-heh)

 

[cwol97401]

As I look at an aircraft making its approach to EUG, I read your post.
The blend door is mechanical on explorers without the electronic climate control panel, its vacuum operated, and in either case (if I understand it correctly) it is usually the door itself mechanically failing. I think you're safe there. The selector switch that turns everything on is a hybrid switch meaning it controls vacuum and electrical current. It sounds like to me that you might have had a meltdown on that switch's electrical harness. shouldn't be difficult to check, remove the two screws directly above the panel and pop the whole radio bezel off and take a peek in behind it with a mirror or a camera. The electrical side of the switch is on the top so you might feel it as well.

 

[chefduane]

EUG - Mahlon Sweet Field. Never been over the mountain but my mom lives in Bend. Bend Muni - BDN.

Aha! Now that you mention it, I did have the radio bezel and HVAC switch panel off a few weeks ago. The bulb behind the fan speed selector switch went out and I swapped it out. I might have futzed something up while I was in there. It was a while ago, tho. Are you specifically referring the to blue/red - hot/cold rotary knob? Regardless, I'll pull the panel and check everything out.

I hope I didn't overload the flux capacitor and blow a dilithium crystal. Might have to swap out the overthruster framisters.

 

[Bobmbx]

EUG - Mahlon Sweet Field. Never been over the mountain but my mom lives in Bend. Bend Muni - BDN.

Aha! Now that you mention it, I did have the radio bezel and HVAC switch panel off a few weeks ago. The bulb behind the fan speed selector switch went out and I swapped it out. I might have futzed something up while I was in there. It was a while ago, tho. Are you specifically referring the to blue/red - hot/cold rotary knob? Regardless, I'll pull the panel and check everything out.

I hope I didn't overload the flux capacitor and blow a dilithium crystal. Might have to swap out the overthruster framisters.

Luckily, your truck comes with Heisenberg Compensators. Probably saved the planet from being disrupted.

 

[lobo411]

As I look at an aircraft making its approach to EUG, I read your post.
The blend door is mechanical on explorers without the electronic climate control panel, its vacuum operated, and in either case (if I understand it correctly) it is usually the door itself mechanically failing.

Even on the non-electronic climate control, the blend door is operated by an electrical actuator motor. At least it is on my 1996 non-ECC XLT.

OP, completely lower the glovebox by depressing the two plastic ears that hold it up. Turn the engine to key on engine off (all electrical devices powered, engine off) and turn on the vent. Then turn the temperature control from hot to cold and vice versa. You should hear a medium-pitched growling sound as the actuator moves the blend door. If not, your motor is fried.

 

[cwol97401]

Even on the non-electronic climate control, the blend door is operated by an electrical actuator motor. At least it is on my 1996 non-ECC XLT.

OP, completely lower the glovebox by depressing the two plastic ears that hold it up. Turn the engine to key on engine off (all electrical devices powered, engine off) and turn on the vent. Then turn the temperature control from hot to cold and vice versa. You should hear a medium-pitched growling sound as the actuator moves the blend door. If not, your motor is fried.

I learn more every day. I like. Being wrong. It humbles me

 

[cwol97401]

EUG - Mahlon Sweet Field. Never been over the mountain but my mom lives in Bend. Bend Muni - BDN.

Aha! Now that you mention it, I did have the radio bezel and HVAC switch panel off a few weeks ago. The bulb behind the fan speed selector switch went out and I swapped it out. I might have futzed something up while I was in there. It was a while ago, tho. Are you specifically referring the to blue/red - hot/cold rotary knob? Regardless, I'll pull the panel and check everything out.

I hope I didn't overload the flux capacitor and blow a dilithium crystal. Might have to swap out the overthruster framisters.

I was referring to the vent/AC knob but probably good to check them all.

 

[lobo411]

I learn more every day. I like. Being wrong. It humbles me

No worries...been there plenty of times myself!

 

[Gadget X]

My $0.02 is on the blower motor resistor on the box the heater core is in, under the hood. Did it smell like leaves were on fire? If so, I'll bet that's it. There is an electrical plug to unplug, the I think 2 screws hold the resistor assembly in the heater box. It's an easy replacement! Good luck!

 

[chefduane]

I changed out the blower motor and resistor a few weeks ago. Both seem to be functioning fine. Doesn't the resistor control blower motor/fan speed? The fan speed switch still functions as it should. Low blows low, high blows high.
Its the temperature control that is non-functioning.

 

[chefduane]

...and as I mentioned above, the smell was electrical in nature. No burning leaves smell.

 

[lobo411]

I changed out the blower motor and resistor a few weeks ago. Both seem to be functioning fine. Doesn't the resistor control blower motor/fan speed? The fan speed switch still functions as it should. Low blows low, high blows high.
Its the temperature control that is non-functioning.

Check the actuator. What happens is that the blend door has a D shaped shaft and the actuator a D shaped hole. Eventually, part of the D shaft breaks off, and either the actuator spins ineffectively, or it gets jammed and that might burn out the motor.

 

[cwol97401]

I changed out the blower motor and resistor a few weeks ago. Both seem to be functioning fine. Doesn't the resistor control blower motor/fan speed? The fan speed switch still functions as it should. Low blows low, high blows high.
Its the temperature control that is non-functioning.

Chefduane, have you had an opportunity to do any investigating?:shifty_ey

 

[chefduane]

Chefduane, have you had an opportunity to do any investigating?:shifty_ey

... not as yet. I plan to get into it on Monday aft.

 

[koda2000]

yes, the blower ballast resistor controls the fan speed by varying the voltage delivered to the fan. they get quite hot (that's why they're housed in the heater plenum air flow) but if they go bad they just stop working. As the only thing not working is the blend door function, I'm thinking the blend door actuator got fried. you might want to go to the salvage yard to practice on removing one. From what I recall, it's a bit of a bugger to change, due to it's location, but it can be done. it's just the TEMP that's not working, right? do the other (vent/defrost) air directional functions work? have you ruled out the switch?

 

[chefduane]

yes, the blower ballast resistor controls the fan speed by varying the voltage delivered to the fan. they get quite hot (that's why they're housed in the heater plenum air flow) but if they go bad they just stop working. As the only thing not working is the blend door function, I'm thinking the blend door actuator got fried. you might want to go to the salvage yard to practice on removing one. From what I recall, it's a bit of a bugger to change, due to it's location, but it can be done. it's just the TEMP that's not working, right? do the other (vent/defrost) air directional functions work? have you ruled out the switch?

Correct, it is just the temp function that it not working. All other hvac functions work properly. I have not ruled out the switch as yet. As I write this I am preparing to run a few errands and then start pulling the bezel.. etc.

 

[chefduane]

OK, I pulled the radio bezel, hvac switch panel, and the lower console off and can see no frayed or burned wires nor any indication of a short or wire fritz, etc. And nothing behind the panel smells like it has been burned. And switch panel wiring looks fine also.
SOoooo, I'm off to AutoZone to pick up a blower motor resistor. If that is the problem, it has me baffled as I thought the fan speed was controlled by this resistor, however the fan speed (as controlled by the selector) is functioning just fine. I'll probably pull resistor on Wed as I am booked up till then.
Any other suggestions?

 

[chefduane]

OKAY, so my previous posting was at 5:25pm. It is now 5:50. I must have GHOSTS IN THE MACHINE as now everything is working properly! As I was driving to AutoZone I decided to check operations again and all now seems to be working just fine! Go figure. AC comes on and blows cold, heat comes on and is hot. Nothing seems to be amiss. BUT I know I had (have) some sort of issue as the problem as first described it persisted for 2 days. And I DID have smoke in the cabin. (My wife thinks I was hallucinating.) So I will continue to monitor things and see what happens.

Chef Duane

 

[cwol97401]

OKAY, so my previous posting was at 5:25pm. It is now 5:50. I must have GHOSTS IN THE MACHINE as now everything is working properly! As I was driving to AutoZone I decided to check operations again and all now seems to be working just fine! Go figure. AC comes on and blows cold, heat comes on and is hot. Nothing seems to be amiss. BUT I know I had (have) some sort of issue as the problem as first described it persisted for 2 days. And I DID have smoke in the cabin. (My wife thinks I was hallucinating.) So I will continue to monitor things and see what happens.

Chef Duane

When I had smoke coming from my steering column, I couldnt find the damage until I pulled the connectors off of my MFC and seen the base of the connector had gotten hot
just another thought

 

[chefduane]

when i had smoke coming from my steering column, i couldnt find the damage until i pulled the connectors off of my mfc and seen the base of the connector had gotten hot
just another thought

mfc?