charging issue or bad switch? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

68c10owner · 12-04-2015, 12:06 AM

With the weather being much colder than it has been lately I`m using the heater daily now. I bought the truck in September and havent needed the heater until the last couple weeks. Anyway, I noticed that with each speed of the fan blower switch the voltage gauge drops a bit. Not sure if its a charging problem or if the blower switch is going bad. With the fan off it shows just below 13 volts but with the switch on high, which seems to be the only speed that works, it drops to just above 10 volts. lights are still bright and battery seems to still be charging fine but I cant afford any electrical issues right now. Spent $120 on a battery and didnt really have the money to do it.mine was dead from sitting while my tranny was being rebuilt and I couldnt get my charger from storage so it was easier to just buy a battery.

Liberty · 12-04-2015, 01:08 AM

My voltage drops when the fan is on as well, I always assumed this was normal. However my lights do dim on idle, wipers slow down, fan slows, ect. As long as I'm moving the voltage stays up.

**MikeB** · 12-04-2015, 11:41 AM

Try measuring voltage at the battery with the engine running.

What is the voltage with the fan off?

What does it drop to with the fan on high speed?

12-04-2015, 12:06 AM	#1
68c10owner Registered User Join Date: Oct 2003 Location: Carmichael, California Posts: 3,006	charging issue or bad switch? With the weather being much colder than it has been lately I`m using the heater daily now. I bought the truck in September and havent needed the heater until the last couple weeks. Anyway, I noticed that with each speed of the fan blower switch the voltage gauge drops a bit. Not sure if its a charging problem or if the blower switch is going bad. With the fan off it shows just below 13 volts but with the switch on high, which seems to be the only speed that works, it drops to just above 10 volts. lights are still bright and battery seems to still be charging fine but I cant afford any electrical issues right now. Spent $120 on a battery and didnt really have the money to do it.mine was dead from sitting while my tranny was being rebuilt and I couldnt get my charger from storage so it was easier to just buy a battery. __________________ Anthony

12-04-2015, 01:08 AM	#2
Liberty Registered User Join Date: Feb 2015 Location: Bonham, Texas Posts: 241	Re: charging issue or bad switch? My voltage drops when the fan is on as well, I always assumed this was normal. However my lights do dim on idle, wipers slow down, fan slows, ect. As long as I'm moving the voltage stays up.

12-04-2015, 11:41 AM	#3
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,544	Re: charging issue or bad switch? Try measuring voltage at the battery with the engine running. What is the voltage with the fan off? What does it drop to with the fan on high speed? __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!



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