Disconnect of C3 Blower Fan
10-08-2004, 12:50 AM
#1
Burning Brakes
Thread Starter
Disconnect of C3 Blower Fan
There have been numerous post about how to disconnect the C3 blower fan since it is always on (in low speed mode) even when the AC system is off. All the posts provide instructions on how to disconnect the BROWN wire from the resistor mounted on the top side of the evap. housing (on passenger side).
There are 4 wires that are part of the resistor wiring harness. The instructions state that 1 of the 4 wires is BROWN.
Question: Does the blower fan run continuosly on ALL C-3 models or only the 76 to 82 year models? (I have a 73). If blower runs on low constantly in a 73, which color wire should be disconnected?
Note: None of my 4 blower resistor wires are brown. They are Dark Blue, Yellow, Light Blue and Light Green. The wire colors are factory correct. I checked my 73 and 74 service manuals for wire colors and wire diagrams. There is not a brown resistor wire on a 73 or 74.
There are 4 wires that are part of the resistor wiring harness. The instructions state that 1 of the 4 wires is BROWN.
Question: Does the blower fan run continuosly on ALL C-3 models or only the 76 to 82 year models? (I have a 73). If blower runs on low constantly in a 73, which color wire should be disconnected?
Note: None of my 4 blower resistor wires are brown. They are Dark Blue, Yellow, Light Blue and Light Green. The wire colors are factory correct. I checked my 73 and 74 service manuals for wire colors and wire diagrams. There is not a brown resistor wire on a 73 or 74.
10-08-2004, 12:00 PM
#2
Instructor
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The fan should not run continuously in low speed on a 73. This was done in later models to refresh cabin air with the ventilation in OFF.
I suspect that in previous posts people were trying to disconnect the low speed because of hot air intrusion. While the fan does push some air in it is hot because of other issues (gaps in the firewall, failed sealing in the heater box, defective hot water shutoff valve, etc.), all of which are the root of the problem and should be corrected before disconnecting wires, IMHO.
Is hot air from the vents the reason for your wanting to disconnect low speed? Since you don't have this feature, I suspect that you are getting air from the vents due to gaps in your door and top seals causing a low pressure in the cabin, thus pulling air in from the point of least resistance (vent. system).
I suspect that in previous posts people were trying to disconnect the low speed because of hot air intrusion. While the fan does push some air in it is hot because of other issues (gaps in the firewall, failed sealing in the heater box, defective hot water shutoff valve, etc.), all of which are the root of the problem and should be corrected before disconnecting wires, IMHO.
Is hot air from the vents the reason for your wanting to disconnect low speed? Since you don't have this feature, I suspect that you are getting air from the vents due to gaps in your door and top seals causing a low pressure in the cabin, thus pulling air in from the point of least resistance (vent. system).
10-08-2004, 01:25 PM
#3
Burning Brakes
Thread Starter
Keith: Yes, some heated air is coming into the cabin from the AC vents. The plastic ducting itself is hot to the touch after driving awhile.
Not 100% sure, but no heated, or outside temp air, appears to be coming in from the lower passenger kick panel vent. (Air may be entering via the upper windshield cowl area (passenger side) and getting into the ducting system.?)
I have the heater hose cutoff valve, sealed the evap. housing box, sealed firewall holes, installed trans. tunnel foam collar piece, rear hood weatherstrip, etc. Heat may be "radiated heat" from engine compartment that eventually heats the ducting system after prolonged driving.
When AC is off, I just close the 3 vents via the push/pull *****.
Not 100% sure, but no heated, or outside temp air, appears to be coming in from the lower passenger kick panel vent. (Air may be entering via the upper windshield cowl area (passenger side) and getting into the ducting system.?)
I have the heater hose cutoff valve, sealed the evap. housing box, sealed firewall holes, installed trans. tunnel foam collar piece, rear hood weatherstrip, etc. Heat may be "radiated heat" from engine compartment that eventually heats the ducting system after prolonged driving.
When AC is off, I just close the 3 vents via the push/pull *****.
10-08-2004, 02:19 PM
#4
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With all that you have done, the heat you have is radiated heat from the engine and ex. manifolds to the box. With a 200 deg. block and a 400 deg. manifold less than two inches from a 1/16" piece of plastic, I have placed reflective high-temp insulation on the engine side of the AC box. Ford has some nice factory installed stuff (alum sheet, fiberglass reinforced, insulation on the back) that works adequate on my Town Car, but other styles (JC Whitney sells the stuff in sheets, but the insulation is kind of thick and might not look that attractive.
10-08-2004, 02:28 PM
#5
Drifting
10-08-2004, 03:03 PM
#6
Burning Brakes
Thread Starter
Henry: That is a great paper on the subject. I read it awhile back and followed all the suggestions. It is the best article I have seen re cockpit heat. ALL the ideas and improvements in the paper help alot to eliminate cockpit heat!
I have ordered some "Cool and Quiet" zero clearance heat barrier material. Easy install, reasonable price (on sale now!), and only 1/8 inch thick! Is is designed for firewall, engine compartments, and under the car. This is not the Reflectix type material for under the carpet in the interior.
Pete76Shark has installed it on his car. It looks great and professional in his photos! See the very recent thread "My feet are burning up".
Product can be seen at www.CoolandQuiet.com It is the same under hood/floorpan material that is used by all the major auto manufactures (Jeep, Lexus, etc)
I have ordered some "Cool and Quiet" zero clearance heat barrier material. Easy install, reasonable price (on sale now!), and only 1/8 inch thick! Is is designed for firewall, engine compartments, and under the car. This is not the Reflectix type material for under the carpet in the interior.
Pete76Shark has installed it on his car. It looks great and professional in his photos! See the very recent thread "My feet are burning up".
Product can be seen at www.CoolandQuiet.com It is the same under hood/floorpan material that is used by all the major auto manufactures (Jeep, Lexus, etc)
10-09-2004, 08:05 AM
#7
Race Director
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Location: CORVETTE 77 385 C.I. TEXAS
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On some the blower runs all the time key is on. The point of changing it to have an Off is just that- to turn the blower off & on when needed- it has nothing to do w/ heat. I don't have the stereo on all the time either- rarely on. Changed it a long time ago on the 77 & wrote it. Have done it on other cars.