A/C Switch

D

donald w. ogden

New member
Nov 15, 1999
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Hi guys-

Anyone know how to fix the A/C control so that the fan won't run when the fan
switch is in the "OFF" position? It's very annoying to turn the ignition switch
to "RUN" or "ACC" to play the radio or use the air bag leveling system and have
the A/C blower running, using up battery power. I understand the reason it does
this, but I still don't like it. Any experience out there?

Don Ogden
'77 Royale
 
Remove the plug on the right side (when facing the coach) of the a/c box---near the
brake master cylinder. Bend over the prong for the yellow wire so that it does not
make contact when you reinstall the plug. That is all it takes and the process in
reversable!!
Gary
North Bend, Oregon Coast

> Hi guys-
>
> Anyone know how to fix the A/C control so that the fan won't run when the fan
> switch is in the "OFF" position? It's very annoying to turn the ignition switch
> to "RUN" or "ACC" to play the radio or use the air bag leveling system and have
> the A/C blower running, using up battery power. I understand the reason it does
> this, but I still don't like it. Any experience out there?
>
> Don Ogden
> '77 Royale
 
check out my web page
gene

>Hi guys-
>
>Anyone know how to fix the A/C control so that the fan won't run when the fan
>switch is in the "OFF" position? It's very annoying to turn the ignition switch
>to "RUN" or "ACC" to play the radio or use the air bag leveling system and have
>the A/C blower running, using up battery power. I understand the reason it does
>this, but I still don't like it. Any experience out there?
>
>Don Ogden
>'77 Royale
>
>
>
gene fisher 76 PB/OR/CA
GMC MOTORHOME INFORMATION
mr.era
http://www.california.com/~eagle/
 
Don,

I've not done this before but you have an interesting idea. I agree that
it is a bit annoying and would fun the battery down a bit if the key were
left on for any amount of time.

There is a solution & I'll get up early and prove it up on the dumpster
tomorrow (the shop will be closed and I'll get to play a bit).

The blower & realy is powered by the acc. power from the fuse block. If
you switch the power tap from there to the center lead on the isolator
(alternator output) it would only blow when the engine is running. It does
that already on hi blow because of the current requirement so I do not see
why pulling the other speeds from there as well would hurt!

As I said, I'll try it tomorrow & let you know.

You get the prize for the neat idea of the day!!

Jim Bounds
- -------------------

>
>check out my web page
>gene
>

>>Hi guys-
>>
>>Anyone know how to fix the A/C control so that the fan won't run when the
fan
>>switch is in the "OFF" position? It's very annoying to turn the ignition
switch
>>to "RUN" or "ACC" to play the radio or use the air bag leveling system
and have
>>the A/C blower running, using up battery power. I understand the reason
it does
>>this, but I still don't like it. Any experience out there?
>>
>>Don Ogden
>>'77 Royale
>>
>>
>>
>gene fisher 76 PB/OR/CA
>GMC MOTORHOME INFORMATION
>mr.era
>http://www.california.com/~eagle/
>
>
>
>
 
Hey, it works fine, if you do not want the dash blower to work unless the
engine is on!

There is a 14ga. brown wire coming from the fuse block (output from the top
left heater/AC fuse, cut it and connect a 14ga. wire and feed it through
the firewall. There is a rubber grommet to the left of the fuse block.

Route the wire to the battery isolator and connect it to the center
terminal using an in line fuse holder with a 25amp. fuse.

Insulate the brown wire end coming from the fuse block (always insulate any
bare wires) and pull out the heater/AC fuse. I would also label the fuse
under the front hood so you know what the modification does for the future.

I made the mod to the dumpster and will let you know if it is convienant or
not.

Happy Black Friday,

Jim Bounds
- --------------

>Don,
>
>I've not done this before but you have an interesting idea. I agree that
>it is a bit annoying and would fun the battery down a bit if the key were
>left on for any amount of time.
>
>There is a solution & I'll get up early and prove it up on the dumpster
>tomorrow (the shop will be closed and I'll get to play a bit).
>
>The blower & realy is powered by the acc. power from the fuse block. If
>you switch the power tap from there to the center lead on the isolator
>(alternator output) it would only blow when the engine is running. It does
>that already on hi blow because of the current requirement so I do not see
>why pulling the other speeds from there as well would hurt!
>
>As I said, I'll try it tomorrow & let you know.
>
>You get the prize for the neat idea of the day!!
>
>Jim Bounds
>-------------------

>>
>>check out my web page
>>gene
>>

>>>Hi guys-
>>>
>>>Anyone know how to fix the A/C control so that the fan won't run when the
>fan
>>>switch is in the "OFF" position? It's very annoying to turn the ignition
>switch
>>>to "RUN" or "ACC" to play the radio or use the air bag leveling system
>and have
>>>the A/C blower running, using up battery power. I understand the reason
>it does
>>>this, but I still don't like it. Any experience out there?
>>>
>>>Don Ogden
>>>'77 Royale
>>>
>>>
>>>
>>gene fisher 76 PB/OR/CA
>>GMC MOTORHOME INFORMATION
>>mr.era
>>http://www.california.com/~eagle/
>>
>>
>>
>>
>
>
Jim Bounds/Co-op Motor Works Orlando www.gmccoop.com
 
The end point you are trying to achieve is the ability to turn on the ignition
and not have the heater blower come on. If this is the objective why not a)
make a mod that will take less than 30 seconds to accomplish and b) is
completely reversable in the same amount of time?

Lift the driver's side hood. Unplug the three wire connector on the side of the
heater box (just to the left of the master cylinder). Bend the connector for
the yellow wire out flat. Reconnedt the connector.

Now the fan will not run when the dash control switch is in the lowest position
but runs as before in all the other positions.

Gary & Edie
North Bend, Oregon Coast (rain)

> Hey, it works fine, if you do not want the dash blower to work unless the
> engine is on!
>
> There is a 14ga. brown wire coming from the fuse block (output from the top
> left heater/AC fuse, cut it and connect a 14ga. wire and feed it through
> the firewall. There is a rubber grommet to the left of the fuse block.
>
> Route the wire to the battery isolator and connect it to the center
> terminal using an in line fuse holder with a 25amp. fuse.
>
> Insulate the brown wire end coming from the fuse block (always insulate any
> bare wires) and pull out the heater/AC fuse. I would also label the fuse
> under the front hood so you know what the modification does for the future.
>
> I made the mod to the dumpster and will let you know if it is convienant or
> not.
>
> Happy Black Friday,
>
> Jim Bounds
> --------------

> >
 
Many thanx to all who came up with a solution to this idea.
I took the simple fix of removing the yellow lead from the fan resistor block.
It's a two minute job and it works just fine. You just don't have a "LOW"
position on the fan switch any more. That's OK with me.

Thanx again,
Don Ogden
 
I've gotten around this problem by moving the selector from either "Normal",
"Vent", or "Heat" to "Max A/C".

When the Air Conditioner is running and you're moving down the road, you may
have noticed that the "Max A/C" selection not only closes down some vents to
provide more re-circulation, but also bypasses the fan speed switch, running
the blower at high speed. I think that this position accomplishes the same
thing that Jim Bounds wiring change does; The high current for maximum fan
speed is pulled directly from the alternator. At any rate, I can turn the
key to the accessory position to listen to the radio or to run the air pump
without running the heater fan.

I did make a similar wiring change on the power supply for my Sony sound
system. There is a large separate amplifier and a 10-CD changer, pushing
lots of speakers, including two large 3-way speakers in the rear corner
pillars. We listened to some nice music all night on a recent overnight in
Denver, and ran down the engine battery. The supply for the sound system was
tapped off of the engine battery side of the "Boost" solenoid, with a 10-amp
fuse holder . There was a separate tap from the "Accessory" fuse block which
was used to "switch" power on and off with key operation. I moved the 10-amp
supply to the "coach battery" side of the "Boost" solenoid, but still get
relay switching current thru the "Accessory" fuse.

This allows me to run the sound continuously, if desired, without impacting
the engine battery quite so much.

Jim Bounds, let me know if my radio re-wiring is going to cause any problem!

Olin Boyer
77GMCPB
 
Olin,

No, in fact that is the wiring mod I recommend to all who will listen for
that very reason.
I also suggest to rewire the dash mounted cigarette lighter plug, CB radio,
fan if you have one & even the overhead driver & pass. lights if it is
convienant. All of these items may eather need to be used when parked or
may have some sort of continuous load to the chassis battery when the
engine is off.

There should be no current drains on the chassis battery when the key is
off. That way, you will always have the confidence that you can start your
engine no matter how much fun you had the night before. Lastly, I install
a knife switch on the living area battery to give you the opertunity to cut
all current drains altogether when the coach is in storage, since all the
drains are moved to that battery, opening that switch kills all the drains.

Good thinking Olin,

Jim Bounds
- ---------------------------

>I've gotten around this problem by moving the selector from either "Normal",
>"Vent", or "Heat" to "Max A/C".
>
>When the Air Conditioner is running and you're moving down the road, you may
>have noticed that the "Max A/C" selection not only closes down some vents to
>provide more re-circulation, but also bypasses the fan speed switch, running
>the blower at high speed. I think that this position accomplishes the same
>thing that Jim Bounds wiring change does; The high current for maximum fan
>speed is pulled directly from the alternator. At any rate, I can turn the
>key to the accessory position to listen to the radio or to run the air pump
>without running the heater fan.
>
>I did make a similar wiring change on the power supply for my Sony sound
>system. There is a large separate amplifier and a 10-CD changer, pushing
>lots of speakers, including two large 3-way speakers in the rear corner
>pillars. We listened to some nice music all night on a recent overnight in
>Denver, and ran down the engine battery. The supply for the sound system was
>tapped off of the engine battery side of the "Boost" solenoid, with a 10-amp
>fuse holder . There was a separate tap from the "Accessory" fuse block which
>was used to "switch" power on and off with key operation. I moved the 10-amp
>supply to the "coach battery" side of the "Boost" solenoid, but still get
>relay switching current thru the "Accessory" fuse.
>
>This allows me to run the sound continuously, if desired, without impacting
>the engine battery quite so much.
>
>Jim Bounds, let me know if my radio re-wiring is going to cause any problem!
>
>Olin Boyer
>77GMCPB
>
>
>
 
Olin,

Uah, yea- that could work too! Hey I like cuttn inta stuff though! Don't
cornfus me wif da facts!! Actually, that is a great way to electricall do
pretty much the same thing.

The only draw back is the hi blow relay would be engeged if you switch to
hi making a slight current drain. I think the best way is to put the
switch between 2 speeds, that way the relay would not be engaged but the
fan would stop.

Jim Bounds
- --------------------------

>I've gotten around this problem by moving the selector from either "Normal",
>"Vent", or "Heat" to "Max A/C".
>
>When the Air Conditioner is running and you're moving down the road, you may
>have noticed that the "Max A/C" selection not only closes down some vents to
>provide more re-circulation, but also bypasses the fan speed switch, running
>the blower at high speed. I think that this position accomplishes the same
>thing that Jim Bounds wiring change does; The high current for maximum fan
>speed is pulled directly from the alternator. At any rate, I can turn the
>key to the accessory position to listen to the radio or to run the air pump
>without running the heater fan.
>
>I did make a similar wiring change on the power supply for my Sony sound
>system. There is a large separate amplifier and a 10-CD changer, pushing
>lots of speakers, including two large 3-way speakers in the rear corner
>pillars. We listened to some nice music all night on a recent overnight in
>Denver, and ran down the engine battery. The supply for the sound system was
>tapped off of the engine battery side of the "Boost" solenoid, with a 10-amp
>fuse holder . There was a separate tap from the "Accessory" fuse block which
>was used to "switch" power on and off with key operation. I moved the 10-amp
>supply to the "coach battery" side of the "Boost" solenoid, but still get
>relay switching current thru the "Accessory" fuse.
>
>This allows me to run the sound continuously, if desired, without impacting
>the engine battery quite so much.
>
>Jim Bounds, let me know if my radio re-wiring is going to cause any problem!
>
>Olin Boyer
>77GMCPB
>
>
>
 
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