Date: Tue, 15 May 2007 13:15:41 -0400
Reply-To: dvdclarksn@AOL.COM
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From: David Clarkson <dvdclarksn@AOL.COM>
Subject: update on a/c fuse blowing
In-Reply-To: <Pine.LNX.4.64.0705110330190.7629@birdbird.example.com>
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We are still trying to track down the problem blowing the 50 amp fuse with the 90 Westy a/c. We have fed power just to the fans and on 3 or 4 speed it blows a 30 amp test breaker. I really dread pulling down the housing for the evaporator to check for a bad wire but it seems to be inevitable. The fans run smoothly on 1 and 2 speed and originally ran for about 5 minutes on the high speed before installation so it's looking like a short to ground problem with the wiring. We also found that once the pressure switch was replaced (used, working switch) that the high side pressure was approaching 350 psi before all of the r134a was added. The final problem we have found is with the condenser cooling fan cycle not coming on. I think that this is related to the pressure switch. Aside from the obvious troubleshooting which would be to somehow test the switch and then the wiring to the 2nd stage relay to the fan (comes on when coolant temperature increases as it should) is there something that I am missing that might link these symptoms. Thanks to all for your time and help with this.
David Clarkson
90 Westy (239k)
-----Original Message-----
From: mattroberds@cox.net
To: vanagon@gerry.vanagon.com
Cc: dvdclarksn@AOL.COM
Sent: Fri, 11 May 2007 5:11 AM
Subject: Re: evaporator cabinet in place now have pressure switch/50 amp fuse blown-long
> From: David Clarkson <dvdclarksn@AOL.COM>
> Date: Thu, 10 May 2007 09:14:49 -0400
>
> I started the engine turned on the a/c set to high and the highest fan
> speed. It ran for about 2 seconds then the fans cut off. Upon further
> inspection the fan switch test okay and when checking the other fuses
> behind the panel in the rear left cabinet I found that the 50 amp fuse
> was blown and the pressure switch on the high side below the service
> valve was burnt up.
I would check very carefully for a wire that got pinched or crushed
during installation, and any possible mis-wiring that happened on
installation. It really sounds like there was a dead short to ground
somewhere in the A/C wiring.
If the pressure switch is fed from +12 V, you might look for a short to
ground after the pressure switch - or possibly the swich shorted
internally, in which case replacing the switch will probably fix it.
If it's a switch to ground, look for a short to +12 V before the switch.
It might be helpful to make up a jumper wire with a fuse holder near one
end. Put a 20 A or 30 A fuse in the holder and connect that end to the
battery, then use the other end to power different parts of the A/C
system as installed. You might also have to jumper around pressure
switches to get the system to behave as if it was actually running.
This way, you can blow up cheap fuses and pieces of wires while tracking
it down, instead of expensive fuses and pressure switches.
Matt Roberds
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