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Sharrin

Sharrin 3/29/2021

2005 Ford Explorer Sport Trac XLT 6 Cyl 4.00L

Body & Interior

HVAC control panel gets VERY hot-to-touch only when headlights are on??

Approx. 3 mo. ago, I noticed the panel behind the far left HVAC knob got so hot, it burned the front of my index finger when turning the knob. There was no smell, the heat/ac work fine, & it gets hotter the more I drive. I could not afford a mechanic. I researched & read somewhere that if one of the HVAC switches is bad, it could cause this to happen. So, I ordered all 3 switches & put them in myself. No solution. But, since I could drive a few blocks (to a store) & it didn't heat up, I did so - and noticed that when the headlights were turned off, it didn't seem to change, & when they were on, the area behind the knob got warmer. To make sure I wasn't imagining things, I drove it about 6 or 7 mi. where I'd previously been unable to go, didn't turn on my lights, and there was no heat at all! Now, I'm in CA, & I was supposed to get smogged this year so I could renew my reg., & because of this, I couldn't. I still have to do that. Please help me. I'm obviously not a mechanic. Help. :)

1 Answer


Jimm

Jimm 3/31/2021

You are on the right track, diagnose the issue further -without throwing money (parts and labor) at the problem.

First search and perform an HVAC self-test procedure: 'How To Perform A Ford Diagnostic Test (Self-Test) Procedure for EATC Modules' = reference either YouTube or repair manual.

https://circuitboardmedics.com/
15-C Pelham Ridge Drive, Greenville, SC 29615

https://troubleshootmyvehicle.com/.../...e-blower-switch-1
Use a volt-ohm meter; either digital or analog, and the wiring diagram or schematic from a service manual.

To obtain an electrical scheamatic / wiring diagram - try the local libraries in your area, or a used service manual for the '05 Explorer from these sources:

www.ebay.com;
www.halfpricebooks.com;
www.rockauto.com;
www.thriftbooks.com;
www.autozone.com;
www.chiltonDIY.com - to list only a few.

search for the HAYNES manual #36024 - or it's equivalent.

Test the HVAC control panel wiring (supply) for current, voltage (ignition key 'on' with 12 VDC supplied) and then the ohms resistance (key 'off'), and compare with the electrical schematic and amperage draw (demand) for the circuit and to the switch control panel.
If there is an electrical short in the switches or related wiring, determined by the meter measurements, this could cause the elevated or heated temperature condition.

One clue is the headlamps 'on' which causes the HVAC panel area to heat up as you have observed.

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