Blower Motor Resistor
Thread Starter
Heel & Toe
Joined: Jun 2002
Posts: 24
Likes: 0
From: bathurst nb
Blower Motor Capacitor
The inline capacitor for my blower/heater motor on my 78 Vette is kaput.I thought it was a broken wire but there is an inline disconnect.Tried turning on the curcuit with no capacitor to the blower and the blower will function.
1. Is it not recommended to run the blower motor without a capacitor ?
2. What size capacitor was it if I need to replace it? Even my manual doesn`t say. Does capacitor size matter ?
1. Is it not recommended to run the blower motor without a capacitor ?
2. What size capacitor was it if I need to replace it? Even my manual doesn`t say. Does capacitor size matter ?
Last edited by spikertom78; Jun 5, 2005 at 06:13 PM. Reason: wording
Racer
Joined: Jan 2003
Posts: 383
Likes: 0
From: Columbia SC
I just checked my wiring diagram for my 76 and it does not show the motor start cap either. I looked at mine from what I can see and it has nothing on it.
The cap must be 12volts cause the motor is but the other variable is it capacitance rating.
I would imagine any cap from any car with a similar blower motor will do the trick
The cap must be 12volts cause the motor is but the other variable is it capacitance rating.
I would imagine any cap from any car with a similar blower motor will do the trick
Race Director
Joined: Oct 2000
Posts: 11,891
Likes: 3
From: Kansas City, MO ...I'd like to go fishing and catch a fishstick. That'd be convenient. - Mitch Hedberg
I just went through all the wiring on my blower motor and I don't recall a cap.
There is the Blower Hi relay which is mounted high on the firewall is $10 at the local auto parts store.
Then there is the blower resister which is mounted on the top of the air box. If you remove it you just see a bunch of coiled wires. Which is not as cheap and cannot be found at the local auto parts store.
Are you referring to either of those or are you talking about something completely different?
There is the Blower Hi relay which is mounted high on the firewall is $10 at the local auto parts store.
Then there is the blower resister which is mounted on the top of the air box. If you remove it you just see a bunch of coiled wires. Which is not as cheap and cannot be found at the local auto parts store.
Are you referring to either of those or are you talking about something completely different?
Racer
Joined: Apr 2005
Posts: 339
Likes: 1
From: San Diego CA
I'm not certain, but I thought that capacitor was related to the radio. When the blower gets turned on, or when it switches speeds, it causes a spike in the electrical system.
Without that capacitor, that spike will cause "popping" in the radio. There is actually another radio capacitor mounted on the steering column that suppresses other spikes as well. Those old radios were not very robust and required all kinds of tricks to keep them sounding good.
I can't guarantee it, but aside from the radio issue, that blower motor would most likely work fine without that capacitor.
Good luck...
Without that capacitor, that spike will cause "popping" in the radio. There is actually another radio capacitor mounted on the steering column that suppresses other spikes as well. Those old radios were not very robust and required all kinds of tricks to keep them sounding good.
I can't guarantee it, but aside from the radio issue, that blower motor would most likely work fine without that capacitor.
Good luck...
Advanced
Joined: Aug 2002
Posts: 84
Likes: 0
From: Riockwall Texas
The comments on the relay and resistors is right on. The capacitor can not be "in line" with the 12V for the blower motor, or the motor will never run. A capacitor charges up from 0V to the source voltage (12V in this case) and then blocks any current flow.
The capacitor is in parallel with the 12V, acting as a filter to prevent spikes from getting distributed by the wiring harness to other items on the harness (Radio, etc). The voltage rating is probably in the 100V range or maybe even greater. 12V automotive is a very noisy power when used through relays and switches.
The only harm in not using the capacitor would possibly be some excess noise on the radio.
The Hi Blower relay applys full 12V through a #10 wire to the blower motor. The relay is activated by the Hi blower position on the H & A/C blower switch. The other settings send 12V through the resistor block mounted in the heater-A/C box. If you are missing one of the lower speeds, probably one wire coil is open, if the Hi speed doesn't work, look at the relay and its source of 12V.
Good Luck
The capacitor is in parallel with the 12V, acting as a filter to prevent spikes from getting distributed by the wiring harness to other items on the harness (Radio, etc). The voltage rating is probably in the 100V range or maybe even greater. 12V automotive is a very noisy power when used through relays and switches.
The only harm in not using the capacitor would possibly be some excess noise on the radio.
The Hi Blower relay applys full 12V through a #10 wire to the blower motor. The relay is activated by the Hi blower position on the H & A/C blower switch. The other settings send 12V through the resistor block mounted in the heater-A/C box. If you are missing one of the lower speeds, probably one wire coil is open, if the Hi speed doesn't work, look at the relay and its source of 12V.
Good Luck
Racer
Joined: Jul 2003
Posts: 401
Likes: 0
From: texas,, at last
hi,
i don't want to hi-jack this thread but i've a problem with the coil thing on top of the heater box,
when it's connected the heater fan will not work, when i disconnect the multi plug from it the fan will then work but only on the highest speed setting,
anyone any ideas,
thanks,
neil
i don't want to hi-jack this thread but i've a problem with the coil thing on top of the heater box,
when it's connected the heater fan will not work, when i disconnect the multi plug from it the fan will then work but only on the highest speed setting,
anyone any ideas,
thanks,
neil
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
I'm pretty sure the high speed wiring is direct to the blower motor. On my 74 there is a separate line for the high speed blower connection and it has an inline fuse under the left inner fender by the junction from the alternator. If your lower speeds aren't working I would check to make sure you have 12 volts at the connector to the resistor. If you do then you have a bad resistor. If you don't have 12 volts at the connector you have a wiring problem. Get a wiring diagram and look for a break in the power line to the resistor.
Race Director
Joined: Oct 2000
Posts: 11,891
Likes: 3
From: Kansas City, MO ...I'd like to go fishing and catch a fishstick. That'd be convenient. - Mitch Hedberg
Originally Posted by camaroneil
hi,
i don't want to hi-jack this thread but i've a problem with the coil thing on top of the heater box,
when it's connected the heater fan will not work, when i disconnect the multi plug from it the fan will then work but only on the highest speed setting,
anyone any ideas,
thanks,
neil
i don't want to hi-jack this thread but i've a problem with the coil thing on top of the heater box,
when it's connected the heater fan will not work, when i disconnect the multi plug from it the fan will then work but only on the highest speed setting,
anyone any ideas,
thanks,
neil
Here is where you can find a replacement
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
