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A/C and fan

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Old 12-18-2008, 11:50 PM
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Car: 1985 Z28
Engine: 305 LG4
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A/C and fan

My fan doesn't come on automatically when the a/c is on, like it is supposed to. I have tried troubleshooting it and can't find anything wrong. The fan does come on when the engine reaches 220*, but my helm manual says it should run whenever the a/c is on to maximize the a/c. I grounded the fan to run constantly and that helps out the a/c, but I don't want my fan running constantly.

Can I just run an extra ground wire or something to the a/c relay that will ground the fan circuit and kick on the fan whenever the a/c is on, preferably when it is only on "max a/c" mode?
Old 12-19-2008, 06:49 AM
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Re: A/C and fan

On a two fan system the right side fan only turns on with the A/C and the 220 deg temp. Factory spec set- up. You can try, however; once you start this the only outcomes is going to be something bad.
Old 12-19-2008, 08:24 AM
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The MODE LEVER actuates a switch to turn on the fan for the condenser whenever the AC compressor is activated.

The odds are that switch went bad.

Originally Posted by Aaron R.
Can I just run an extra ground wire or something to the a/c relay that will ground the fan circuit and kick on the fan whenever the a/c is on, preferably when it is only on "max a/c" mode?
No. There are other modes beside MAX AC that require the fan for the condenser to run.

Also:

You do not want to have the fan for the condenser to turn on VIA the compressor relay only because there are times you want the to CONDENSER to cool as much as possible so it is ready for the next compressor on cycle.



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Old 12-19-2008, 09:55 AM
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Re: A/C and fan

Thanks for the help, guys. It is a single fan system. I will take the dash apart and look for a switch around the mode lever.
Old 01-05-2009, 11:26 AM
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Re: A/C and fan

Pulled the mode switch out and put in used ones from an 88 and an 89. No difference. Everything seems to be working fine with the switch. Any other ideas?
Old 01-06-2009, 12:19 PM
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You swapped a used one for a used one.

Use an ohmmeter to determine if the blower switch on the mode lever is OK.

Also use the meter to verify there are no opens in the wiring.


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