I hope you guys don't mind my asking you a question. I can't find any answers on Corvette Forum. Well, i FINALLY finished my AC on the vette. UGH! Changed the evaporator core and the little high pressure plastic switch in the compressor. Its working awesome, but...Now my fan stays on all the time! That is when the key is ON, and even when its not over heating or anything WITH the ac and engine OFF! I dont believe we messed with that part of the car. What could it be? I tried changing the relay, same thing. Man..it never ends. Serenity now!!!!!

 

I had the exact opposite problem, my fan(s) wernt coming on at all. And I had some major over heating probs to tackle. So I bought a manual fan switch out of my corvette corner catalog and now i can just turn them off and on at will. Now I run real cool. Here is a tip for you though. When i was doing the wiring, I grounded the fan relay and then traced the grn/wht striped wire to the wrong fan switch. Inside the covering where all those wires were there was two of those. one in the back and one in plain sight. One is the main fan switch and the other is the auxilray. I just took the easy way out and picked the one i saw first.
Make sure you dont do that, or you only have you small fan come on, and not the main fan.
Bowtieguy01
86 vette

 

Hey vettegoslow, why complain? If your fan runs all the time it will keep your engine cooler right? Stop worrying about it and help your friend with his car. l8r

 

GAH SOULBOUNDER!!!!!! Because I don't want to run rich all the time, AND i don't want my fan motor to burn sooner than it should. § Oh, my friend says he is going to take it to a mechanic, that lamen. LoL.

P.S. Its alright.

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[This message has been edited by Vettegofast (edited September 15, 2000).]

 

Did you check the actual grounding switch for the fan? I had the same problem this winter and that's what the problem turned out to be.

 

The ECM uses a pressure switch to determine whether the AC compressor is on. If on, the fan(s) will be commanded on. If off, the fans use temperature logic.

Here's the snag...some years use a switch that is normally closed, and opens under pressure. Other years use the opposite logic. It sounds like you have the wrong switch for your ECM's software, and the ECM thinks the AC compressor is pressurizing full-time.

Quick test: with the engine running but still below operating temp, turn the AC on. If you have the wrong switch, it *should* turn the fan(s) off.

The pressure switch should be located on the high-side compressor line along the passenger side frame rail.

HTH,
-Kevin


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1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

 

Can you tell me where the switch is grounded?

Kevin,
Sounds like you're on to something there. Since this thing just started RIGHT AFTER i fixed my AC. Hmm, i am gonna go try your diagnostics right now. Thanks.

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Update:
Kevin,
I did what you said. Car was runnin at 120 degrees with the AC on. The fan continued. I guess i can rule that out now. I guess i will have to check that ground.

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Remember that this circuit activates by negative ground, so any wire involved that is cut or pinched can cause continuous operation. Double check all wiring routes for a direct to ground short.

 

You shouldn't.

Now, as for the problem
you might want to do that diagnostic after you hit like 180º-200º. IIRC operating temp is 220º.

 

Thanks guys. I will try to get to the bottom of this. I will let you know if i find anything. Lata!

 

If you pulled the plug off the pressure switch, the fans would come on right? (Atleast for the generation which had that logic). Now, if you stuck a jumper wire between the prongs, would that give the same result as just plugging it back in?

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85 2.8L Sport Coupe 5-speed.
Mods: Hpertech chip and powerstat, MSD 6A-L, Crane fireball coil, Accel Cap and Rotor, Dynomax hi-flow cat and catback system with a dynomax magnum race bullet muffler on the i-pipe, K&N filterchargers, Gutted Air Boxes, 8mm Wires, Eibach Sportlines and Tokiko springs/shocks setup, Global west sub frames, Suspension techniqs front and rear sway bars, and good ole 88 IROC wheels with Kumo Ecstas on em!
"It's not the ricers, it's those damn V8's!"

Wins: 2000 V6 Accord, 69 302 Mustang, 2000 Auto VR6 Jetta, 89 Toyota MR2, 90 Civic Si, 76 350 Camaro, 2000 3.8 5-speed Camaro, ~68 Chevelle 350, 92 CRX Si.