a69vette

One minute the AC is blowing nice cold air on high, next thing....no fan. I have low, med & mid-high speeds from the motor. I have test the fan switch, it tests OK. I have checked the fuse under the hood by the relay, it's OK. I have changed out the blower relay, no luck. Testing with voltage, the purple line at the relay has voltage in every selection execpt high. Constant 12vdc on the "red" line, but no voltage on the purple line when the switch is in high.
HELP!
Thanks,
Rick


[Modified by a69vette, 3:39 AM 11/22/2003]

RJR99SS

a short in the resistor would be my only guess. But it's odd because a shot resistor usually means you loose all BUT high speed. Some kind of physical damage to the high circuit is all i can think of.

wombvette

There is an extra max a/c high fan switch under the shift console. It is sometimes a source of problems.

a69vette

I have the whole console out. Where am I looking to find a high fan switch?

Thanks,
Rick

http://www.photohost.org/gallery/sho...hp?photo=22076


[Modified by a69vette, 3:47 AM 11/18/2003]


[Modified by a69vette, 3:47 AM 11/18/2003]

redwingvette

The high speed switch turns on a relay that is mounted on the side of the HVAC box in the engine compartment. If the relay is not getting power when it is on high, then the swicth is bad. If it is getting power then the relay is bad.

ImBatman

Rick,

On my '71 the high speed is controlled by a separate wire coming from the horn relay under the hood. This should feed in the purple wire. The wire coming from the horn relay should have an in line fuse. Check that out and see if it is blown. Hope this helps.

a69vette

I've tested the switch with an ohms meter. When in the high position, I have 0 ohms. I've bought a new relay (on the side of the HVAC box), tried that and it did not correct the problem.
Am I missing something? Does anyone have a detail diagram of the '69.

Thanks for the help.
Rick

Ken74Conv

Check the single fuse holder under the drivers side fender. On mine I think
the wire is orange. It feeds the high speed fan.
:cheers:

Tonwoo28

If it's anything like my '80, there's a series of small vacuum hoses behind the glove box/passenger side dash. When I removed my heater core I noticed one of these lines was broken, and I could fill the vacuum with my finger. I stuck a toothpick in the hose with a pair of needle nose pliars until I was able to get it replaced. This allowed for the high setting to operate properly. I hope this helps.

Tony

a69vette

The fuse located by the horn relay was tested, and it is OK. I have 12vdc thru that point.



[Modified by a69vette, 6:29 PM 11/18/2003]

a69vette

There are several vacuum hoses connected at the thumb control area, but I have no idea where they go. Is it possible that a vacuum line controls the high speed of the fan?

Rick

ImBatman

Rick,

Right now none of my vacuum hoses are hooked up and my blower works. I am pretty sure that your system is the same as mine. Have you tested the switch itself to se if the high position is bad. Hang in there I know the feeling. It took 3 wks off and own to get my blower motor working. zwede gave me a lot of help. Maybe he could shed some light on this.

Good Luck
Wade

redwingvette

There are 4 wires going to that relay. Two wires are thicker than the other two. One thick wire should have 12 volts on it all the time. It leads back to the horn relay and has a in-line fuse. The other thick wire should lead to the fan motor.Then a thin wire should have 12 volts on it when the switch is on high. The fourth wire goes to a ground.

a69vette

I tested the switch with a ohms meter. The switch tests OK in the high position (I have 0 ohms when in high). I quess I'm trying to fiqure out the power path. Does the power come from the horn relay to the switch then out to the motor, or what path does it take?

Thanks,
Rick

a69vette

OK, The red line has a constant 12vdc. The purple line has limited voltage as the switch changes positions, untill it gets to the high. On high, the purple line has no voltage. So it sounds like I need to look into one of the smaller wires that contains the 12vdc for the high speed.

Thanks,
Rick

GATOR454

I had the same problem, all speeds except for high. Like Ken74Conv said it was a bad fuse. The fuse was located under the brake master cylinder. I replaced mine with a 30 amp self reseting circuit breaker.

frank0075

I have the same problem with my 75. Changed the relay , changed the switch., changed the fuse. Only high speed fan setting doesn't work. Where is this relay in the consol. I can't find it either?

a69vette

As stated in the top of the post: The fuse is OK. I have 12 volts thru the fuse. I still belive that my challenge is knowing the electrical path out of the switch to the blower.

a69vette

I would rather replace a clutch, than chase electrical problems. :confused:

a69vette

I have tested thru the lead that attaches to the high relay. The red lead is constant 12 vdc, the purple was less than 12 and the green lead receives 12 vdc when the switch is turned on high. The small black lead is the ground lead.
Now, I've proven that I have power to the relay. I have installed a new relay, and the fan STILL does not blow on high.
NOW WHAT! :mad

Here's a link to the relay lead.
http://www.photohost.org/gallery/sho...hp?photo=22223


[Modified by a69vette, 10:37 PM 11/18/2003]


[Modified by a69vette, 10:38 PM 11/18/2003]