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Re: blower again
Could that part be the resistor? Would that part make the blower not function on high if it was bad? -
Re: blower again
High blower speed bypasses the resistor.Bill Clupper #618Comment
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Re: blower again
Could someone explain what the resistor does? I would like to know its function in the scheme of things related to AC function.Comment
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Re: blower again
The resistor controls all blower speeds except High; for High blower speed, the blower relay connects the blower motor directly to the red power feed wire with the in-line 30A fuse from the horn relay screw terminal buss.Comment
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Re: blower again
A/C 1967 CAR!!!! I don't know what you have.......
The resistor that is mounted in the heater box (3 leads) is in the circuit when low or medium speed is selected. Power source at this time is the brown wire coming from the "under dash" fuse block. The RELAY mounted on the A/C box is deenergized in low/med blower setting.
When High blower is selected the resistor is no longer in the circuit, the relay mounted on the A/C box becomes energized and the blower motor power source is switched to an inline fuse in the red #12 lead coming to the relay. That red lead gets its power source at the horn relay. Therefore there will be 12vdc on this lead with the ignition switch on.
If you have 12vdc on this red wire at the A/C relay then the relay or associated wiring is bad. Make sure there is an adequate ground on the A/C relay.Comment
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Re: blower again
The resistor reduces the voltage available to the blower motor in the low/med speeds.(2 voltage levels). The resistor is mounted in the heater A/C air stream to cool the resistor when in use. If you operate the blower with the resistor out of the box, you can possibly burn up the resistor prematurely....Comment
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Re: blower again
I have a 74' T-top and the blower would not work on high. I found on the electrical wiring diagram that there is a fuse on the electrical feed for the high speed position only. As I recall, from doing this several years ago, the in-line fuse was in a holder that was in the engine compartment up near the firewall on the drivers side. I took me a few minutes to find it and 30 seconds to replace the fuse and all worked as it should. I believe finding this fuse blown is fairly common on C3's but do not know why they blow as the new fuse has been fine for the last 6-7 years.Comment
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Re: blower again
The in-line fuse that transports power from the engine compartment B+ rail (side of horn relay) for running the blower motor on its MAX speed setting is WELL known and the first place most look for problems when the fan works on its lower speed settings but not on the highest setting.... The fuse isn't a secret and it's clearly depicted in the AIM under Option Section UPC C60 in the wiring diagram that details the additional electrical specifics introduced with the A/C option.
There are two common reasons for the fuse to blow (it shouldn't as it's amperage was selected with ample design safety margin for the circuit):
(1) There's a problem in the wiring harness with the high speed fan power wire being 'skinned' and randomly shorting to ground as it crosses the engine compartment....
(2) The fan motor is reaching the end of its useful life (brush and/or bearing wear) causing start-up transient current to climb well above normal level(s).
You trouble-shoot #1 by careful visual inspection of the fan's high speed power line and replace/repair as required. If that doesn't remedy the fault (blowing fuses), it's probably time to bite the bullet, pull the original fan and either have it re-built or replace it.Comment
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