Strange climate control systems function

Ok so this has been like this ever since iv owned the truck with only 58000 miles on the odometer. This iv never seen or heard of before and now starting to wonder if this is normal on more modern day cars.

Ok... So it appears that my climate control (temperature and position) is also controled by my lights. More so whenever I switch my parking lights on I can hear/feel a difference in temperature.

While I'm driving and have the temp setting to all the way cold and air position to head/feet, ill turn my lights on and will feel the air get cooler and the air coming out of the upper middle vent get stronger. I turn the lights off and the air gets slightly warmer and the air out of the upper middle vents becomes weaker?? I also notice that I can hear my temperature control door under the dash continuously changing like its hunting for the right position, I kinda figured this was normal as to keeping consistent temp.

My truck is an 04 and dont really know if my system is equipped with auto climate control, but find this very weird. My dad has an 03 and his does not do this.

Is this normal? If not what could be causing this

 

Ok so I was out messing around with this on my way home. It seems that with my lights off and my temperature setting set at full cold, my temp won't go to full cold but instead bumped to a warmer setting then straight cold. With my temp setting still on full cold and i turn my lights on I can then feel the temperature drop and am now getting straight full cold. Turn lights back off, I feel the temp rise slightly.

Anyone have any idea why my lights are playing a factor with my hvac systems? I'm stumped

 

I have an 04 and this has never happened to me. Im no expert, but my first thought is because you got the truck with 58k i would assume the previous owner(s) played with the wiring, or maybe a short of some kind. I can only isuggest (IM SHITTY WITH ELECTRICAL) is getthe factory service manual (fsm) and trace the wiring down for both lighting and climate. Also look for "non factory" wiring. You know, bubble gum, duct tape, wire nuts. Basically anything that looks hacked. Is the truck stock? Any upgrades? Quick story. I had a 69 datsun roadster 2000 Years back.. Put a grant gt steering wheel on it, but never wired up the horn button. Because of that, i ended up having no brake lights when I hit the pedal. So i bought a new brake light switch and that didnt help. Eventually a friend came over and figured it out. Moral is, car electrics are weird. Just be patient, some one who is smarter than me will chime in. Good luck. Btw the 1st-gen-tacomas dont have climate control like newer cars. Just good ole on/off hot/cold switches..

 

I kinda figured it wasent normal , but figured id get some input first before looking around. I do have a passenger side air bag dash switch bulb out. Its been out since the truck was bought, kinda doubt the two would be connected but anythings possible. Iv been behind the glovebox before and have not noticed anything out of the norm such as extra/nonstock electrical wires. Everything appears to be stock and untouched, wire loom is all in tact. As far as modifications that iv done... everything that iv done is run off its own fuse board and wiring and nothing has been spliced together with different componets or excisting wiring harnesses. I will pull the glovebox out and check the wiring harness to the HVAC system in more detail.

On an update, when leaving to go to work this morning i messed around with it and the symptoms were still there. However, when i got to work i messed with it before shutting the truck down and everything was normal and working like it should. The lights had no affect on temp position!?!? If it was a wire shorting or something hooked up wrong, wouldnt the symptom manifest itself all the time? With this evidence this kinda leads me to believe that possibly the control unit or amplifier behind the climate control knobs my be the culprit and not the wiring? Due to the fact that the climate control illumination is in close proximity to the amplifier and circuit board.

Please keep the inputs coming, any suggestions are welcome.

 

agreed, something electric is wrong there.

try testing the voltages and resistance to the fan and compressor to see if both are effected and to see if the voltage drops before or after the controls, perhaps the fan resistor relay is the problem

 

When you mean compressor, do you mean A/C compressor?

 

Imo if it's a short, that doesn't mean it will always be shorting. Here's the best link anyone will ever give you for this truck.http://web.archive.org/web/20080731033603/http://www.ncttora.com/fsm/
Scroll down to 2003. There super similar, im sure. Very helpful. Id check for continuity, resistance, blah blah blah. Trace your headlight wires and see if they're connected correctly. This is truly a weird symptom.

 

Well i found out what the problem was. Long story "short" (pun intended). Between the A/C amplifier and the curcit board that the illumination bulbs and knobs are attached to. There is a white wire strip that links the two circuit boards together. Well that wire strip was pushed up agains a sharp solder on the circuit board for the illumination/control knob board and i guess over time with vibration that solder tit peirced the insulation and was causing the short when i would turn my lights off and on. So i flipped the wire strip and coated it with liquid tape and the problem is taken care of.

Also it was nice to have my dads truck to help confirm the problem. He let me remove his unit and plug it into my truck and that narrowed it down to the curcuit boards and not a short somewhere else in the truck. I deff lucked out on that.

 

glad you got it sorted, stuff like this can give you gray hair troubleshooting it.

 

Good job figuring it out!