HVAC fan switch keeps burning out

ANDREW2005

MEMBER
2005 SATURN ION
2.0L
4 CYL
2WD
MANUAL
153,000 MILES

In my car listed above Redline. I have consulted my mechanic who has advised me to replace the harness behind the switch itself. I will be doing that soon as I have ordered the part. But either way I need to replace the fan speed selector (switch). Is the speed selector (switch) the same on a car with Air Conditioning as it is in one without? My car has A/C but I am having trouble finding a whole panel that has A/C at my local salvage yards. Are the switches interchangeable or does having A/C affect this?

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1 Reply

CARADIODOC

MECHANIC
33,871 POSTS

I can't find anything to indicate the two systems use different switches.

Your mechanic is right about the connector, but you don't have to replace the entire harness. This is real common with all high-current switches, including ignition switches, head light and dimmer switches, and heater fan switches. This happens to ignition and heater fan switches much more often when the fan is used on the higher speeds often, and when switching the ignition switch on and off while the fan switch is in a high-speed position. The arcing across the contacts leads to the failure.

This can also be caused by a less-than-perfect connection between a mating pair of terminals. When just a little resistance develops between them, that causes heat to be generated when current flows through it. That heat leads to more resistance which leads to more heat. That heat migrates from the bad connection to the switch's contacts, or the other way around. When you only replaced the switch, the bad connections between the terminals was still there. That is what causes the repeat switch failures.

Your connector is a little small to work on, but you can still do the same procedure. Cut out the two burned terminals from the connector body, and cut away the melted part of the connector. Replace the two terminals with universal crimp-type terminals of the same size. You can also snip that connector from a car in the salvage yard and remove two clean and shiny terminals from it. Be sure to get at least four inches of wire with those terminals.

Cut off four inches of the wire with the burned terminals. That wire will be hardened from overheating and solder won't adhere to it. With the universal terminals, crimp them to four inches of new wire of the same diameter, but solder them too to insure a good connection. Plug in the connector with the melted areas cur away, then plug in the two new terminals individually. Splice the wires to the car's wires. Solder those connections, then seal them with heat-shrink tubing. Never use electrical tape in a car as it will unravel into a gooey mess on a hot day.