73-87chevytrucks.com

73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: DirtyLittleSecret on January 03, 2009, 10:25:36 pm

Title: Heater Blower Failure...resistor?
Post by: DirtyLittleSecret on January 03, 2009, 10:25:36 pm: Hey gang, just had my heater blower fail. Did a search, and did not find anything.
Replaced the fuse (looked iffy it was so old), and replaced the fan motor to no avail...is there a resistor or something somewhere? I note what looks like one in line from the fan, but am uncertain. What else should I check? Oh, its getting cold again, and I've got a 78 K20 w/ 350.
Much appreciated!
Title: Re: Heater Blower Failure...resistor?
Post by: VileZambonie on January 04, 2009, 08:00:19 am: 78 K20 with or without AC?

Get a test light and go directly to the connection at the fan and see if your test light (alligator clip to a good ground) lights up in any speed with the key on.
Title: Re: Heater Blower Failure...resistor?
Post by: DirtyLittleSecret on January 04, 2009, 05:43:45 pm: Sorry about that! W/O AC. Tested, and found nothing. Also tested the fan, and it works. Any other ideas?
Title: Re: Heater Blower Failure...resistor?
Post by: VileZambonie on January 04, 2009, 07:15:46 pm: key on engine off do you have B+ at any of the terminals on the resistor at any speeds?
Title: Re: Heater Blower Failure...resistor?
Post by: DirtyLittleSecret on January 18, 2009, 11:55:58 pm: Sorry it took so long, but been gone for work. Replaced the resistor, and still found nothing. No power to the resistor. Any other ideas? Switch?
Title: Re: Heater Blower Failure...resistor?
Post by: Irish_Alley on January 19, 2009, 12:29:04 am: i guess my truck had the same problem due to its always on once you turn the key and always stays on low took the dash off to see what the problem was and saw the resistor switch wasn't even connected was to busy with the keyless entry to even look at how its rigged up
Title: Re: Heater Blower Failure...resistor?
Post by: ccz145a on January 19, 2009, 08:17:40 am: Quote
always stays on low
They are supposed to always stay on low, that is not a problem.
Title: Re: Heater Blower Failure...resistor?
Post by: DnStClr on January 19, 2009, 11:13:17 am: With the key on you should be getting B+ power at one of the switch terminals and at one of the resistor terminals like Vile said. If not, recheck the fuse with the test light. If the light comes on at the fuse and not the resistor or switch then the wiring is bad from the fuse.
Title: Re: Heater Blower Failure...resistor?
Post by: Irish_Alley on January 19, 2009, 11:11:49 pm: Quote from: ccz145a on January 19, 2009, 08:17:40 am
Quote
always stays on low
They are supposed to always stay on low, that is not a problem.
even when you switch it to hi?
Title: Re: Heater Blower Failure...resistor?
Post by: ccz145a on January 20, 2009, 07:56:11 am: Quote from: Irish_Alley on January 19, 2009, 11:11:49 pm
Quote from: ccz145a on January 19, 2009, 08:17:40 am
Quote
always stays on low
They are supposed to always stay on low, that is not a problem.
even when you switch it to hi?
No, but my point was there is no off.
Title: Re: Heater Blower Failure...resistor?
Post by: Irish_Alley on January 21, 2009, 04:39:22 am: lol OK i gotcha
Title: Re: Heater Blower Failure...resistor?
Post by: Bubba13 on January 24, 2009, 12:51:21 pm: did you check the ground wire going to the fan motor. remember it just mounts to fiberglass. if not that , it might be the fan switch on the dash.
Title: Re: Heater Blower Failure...resistor?
Post by: 78 Chevyrado on January 24, 2009, 06:59:03 pm: does the fan work when it's set to high? If yes, it's the resistor or the switch, if no then there's no power or it's the switch. When on high, the resistor is bypassed and runs direct power.
Title: Re: Heater Blower Failure...resistor?
Post by: DirtyLittleSecret on January 24, 2009, 07:18:50 pm: Spent a little time with the tester today, and nothing seemed right. Finally figured it out though. Seems I installed two (2) faulty (but new) fuses. Must have gotten a defective batch of Buss fuses (FYI). Either way, everything's new and working like a champ!
Thanks for all the help guys!
Title: Re: Heater Blower Failure...resistor?
Post by: DnStClr on January 26, 2009, 07:43:02 pm: Good deal. There's nothing like a little heat in January :D