I would strongly advise you if you do not already have them to buy a
full set of drawings from Bluebird.....cost about $85. These drawings
will have the wiring for the upper and lower dash and the one for
the dash to the chassis which you will need. What I am going to
describe is from memory since I dont have the 1982 FC 35 that I
modified anymore or the drawings for it.
In your 1981 FC I believe the dash plug F has the wires from the
lower dash switches for the right and left A/C fans. Each switch has
3 speeds to coincide with the 3 speed A/C fans in the evaporator in
the front inside top compartment. You can see where each of the 3
wires run from the fans to a terminal block in that
compartment. disconnect the wires. Install 3 bosch relays (one for
each speed) for each fan (total of 6 bosch relays). Then run a two
heavy gauge wires from the switched circuit breaker on the left of
the top compartment to each of the bosch banks (again 3 for each
fan). You can actually run the 12VDC wire to the first bosch relay
and then jumper that one to the other two since only one will be used
for each fan at a time. In this configuration the voltage from the
A/C on the dash will now only be used to "trigger" the bosch relay so
full voltage will go to each fan. Look on the side of the bosch relay
and you can see where the 12VDC is connected, the side that will go
to the fan and the grounds. You can easily see which wires are for
the 3 speeds by cutting the wires going to the fans and then
sequentially switching each speed with the A/C fan switch while
monitoring the wire for voltage. For instance switch the left A/C fan
switch to low speed and then with a voltmeter check which of the 3
wires for the 3 wires you cut from the fans has voltage. Then do the
same thing for the other 2 speeds and then the right fan wires. Here
are some pictures of the modification I did to the 1982 FC35 that I
had. Its essentially the same modification that is used on the front
headlights.
http://autos.groups.yahoo.com/group/Wand...m/files/FC . I
intend to do the same two modifications to my PT 40
Tom Warner
Vernon Center,NY
1985 PT 40
AM 7/26/2006, you wrote:
>I have an 81 fc35 on which the Chasis air does not fuction. Of course it
>needs a belt which it getting here shortly. I am not a wiring person so
>how do you add the relay in to get more power to the system?
>
>Chuck
>81fcsb35
>Orange City FL
>
> > I keep hearing that chassis airs are not producing enough cold air
> > for owners of forward controls or for that matter thje PTs. Many
> > owners have taken the compressors and condensers out entirely.
> >
> > I rebuilt the chassis air on the 1982 FC35 that I had including a
> > compressor, air drier, evaporator fans and rewiring the circuits
> > supplying voltage to the condenser and evaporator fans. Also
> > recharged with R134a. Blew air at 39 degrees and the fans due to the
> > increased voltage available to the fans blew what seemed to be twice
> > as much air.. It produces more then enough cold air for the front of
> > the bus even on the hottest days. The A/C compressor is a 10 cubic
> > inch unit capable of providing a maximum of approx 47,000 BTU with
> > R134a at the speed the compressor is turning, although the condenser
> > size is limiting that some. If you need more air you can add another
> > evaporator inside and a larger condenser on top. Remember your roof
> > airs only produce a maximum of 15,000 Btus each.
> >
> > The main thing restricting the volume of cold air produced by the
> > chassis A/C is voltage reaching the condenser and evaporator fans.
> > Bluebird had the voltage routed thru the dash switches (same with the
> > head lights) and the remoting of these switches using Bosch relays in
> > the top solved this problem.
> >
> > tom warner
> > Vernon Center,NY
> > 1985 PT 40 (its chassis air is next)
> >
> >
> >
> > At 04:57 PM 7/25/2006, you wrote:
> >
> >>Just made a trip in our 7731FC and found a way to keep cooler than
> >>before. We use the front roof air as the dash air doesnt do anything.
> >>This trip we bought a clear shower curtain and used expanding window
> >>curtain rods to hold it in place just in front of the hinge to the
> >>bathroom door. We have a closet just across. Worked great to keep cold
> >>air up there with us and we could see out the back window to keep watch
> >>on the boat we were pulling. Hope this works for others as well.
> >>
> >>
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> >
>
>