Re: Viper Fan Saab temperature switch

From: JAMEPC@aol.com
Date: Fri Jun 27 2003 - 21:24:50 EDT


I successfully sent this message weeks ago. Wonder why it's popping up
again? Bad AOL!

In a message dated 6/27/2003 8:56:05 PM Eastern Standard Time, JAMEPC@aol.com
writes:

> Bill,
>
> Thanks for doing the diagram with the manual switches also.
> Maybe you can clear this up for me. When the temp reaches 192 degrees, the
> fan goes from low to high, correct? When the temp drops down to 183, does
> it
> kick back to low or does it stay on high till it drops to 165 and then go to
>
> low? I'm trying to figure out if my Viper fan will run continuously on high
>
> in FL summer with the air on if it can't drop the temp down to 165.
> Won't it always run on low if the temp stays above 156 degrees?
>
> Thanks for any help,
> James
>
> In a message dated 4/24/2003 3:51:50 AM Eastern Standard Time,
> bill@nissley.com writes:
>
> >Bryan,
> >The relays seem to be working just fine, but I am going to use your
> >suggestion for wiring the A/C relay in parallel.
> >
> >As for the position of the thermoswitch, I see your point, but the truth
> >is that the thermoswitch doesn't turn off at the same speed that it
> >turns on. The tests I did on the stove top with a temp probe and a ohm
> >meter were as follows.
> >
> >Low ON = 183
> >Low OFF = 156
> >
> >High ON = 192
> >High OFF = 165
> >
> >I don't know how accurately these test tell what happens during semi
> >constant temperatures achieved by the thermostat opening and closing,
> >but it does tell me that the on temps are different than the off temps,
> >which I think will keep the cycling down. I do know that older mid '80s
> >Saabs controlled their fans this way.
> >
> >My real in truck observations are still minimal. Today the outside
> >temperatures were very mild. The fan would go on in stop and go traffic.
> >When I was freeway driving it stayed off until I got off the freeway I
> >then drove for about a mile and was at work and the fan ran for about 5
> >minutes after I parked. I haven't had any off on fan cycleing except for
> >when the engine was cold and I had the A/C on. As the fan clutch cycled
> >off and on so did the fan.
> >
> >Thanks for your input.
> >Bill
> >
> >-----Original Message-----
> >From: owner-dakota-truck@bent.twistedbits.net
> >[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of M.Bryan
> >Galloway
> >Sent: Wednesday, April 23, 2003 7:03 AM
> >To: dakota-truck@dakota-truck.net
> >Subject: Re: DML: Viper Fan Saab temperature switch
> >
> >
> >This is supposed to be part of my previous post, Oooops.
> >I have two questions, one about the 2nd wiring diagram and the other
> >about
> >the placement of the thermostatic switch.
> >1st: You drew the a/c fan control relay in series with the a/c comp
> >clutch
> >relay. I think its possible that the combined resistance [impedance,
> >actually] MAY be sufficient to reduce current flow to the point that the
> >
> >relays act erratically, or possibly that the voltage drop across the
> >first
> >will cause the 2nd to go erratic. Wouldn't the coils in parallel off the
> >pcm
> >provide full voltage/current to both and operate the way you want them
> >to?
> >2nd: You said you installed the thermostatic switch in the upper radi
> >ator hose. Every liquid cooled volkswagen I've seen puts that switch in
> >the
> >lower area of the radiator near the radiator outlet [lower hose]. Won't
> >placing a 180 switch just downstream of a 180 t-stat have the fan come
> >on
> >when the t-stat opens? I believe the temp controls are set up to work
> >in
> >stages; I.E. high temp leaving the engine opens the t-stat to provide
> >radiator cooling, high temp leaving the radiator enables the [low-speed]
> >fan
> >circuit to increase radiator cooling, and continuing temp increase
> >leaving
> >the radiator enables the the high-speed fan circuit. Won't having the
> >switch
> >in the upper hose cause increased cycling of the t-stat/fan? These
> >question
> >are purely theoretical as I haven't done the install myself, yet and I'm
> >
> >trying to anticipate/head-off operational problems
> >M.Bryan Galloway
> >
> >mbggt@hotmail.com
> >
> >For any thinking person the title "Criminal Justice System" should have
> >been
> >sufficient warning. L. Neil Smith
> >
>
>



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