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  #1  
Old 11-11-2005, 03:08 PM
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Join Date: May 2003
Location: bullhead city, az hot as hell
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300e aux fan question

installed new fan, old one froze, the only time I can get it to go on is by jumpering the green switch( I assume its high pressure switch) on the drier shouldn't it comeon when the a/c is switched on, all fuses are good I switched the front 2 relays nothing, any ideas
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Old 11-11-2005, 03:14 PM
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The a/c aux fan circuit requires the high side pressure to reach the sw. cut-in spec in order to complete the fan circuit. This is when there is a high thermal load on the system. iI the system is short of refrigerant, it will not reach this spec/pressure..
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Old 11-11-2005, 08:01 PM
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the a/c is working great will freeze you out
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Old 11-11-2005, 08:32 PM
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If the fan comes on when you jumper the high pressure switch, then you have tested the integrity of the fan circuit...so, the high side is either not getting to pressure trip point or the switch itself is at fault.
Pressure gauges for high side will tell you that.
Don't assume the fan always comes on when the a/c is on.. it comes on when there is a high thermal load calling for aux fan assistance .. like when ambient temps are high.. a quick look at you eye sight will tell you if you are short of refrigerant .. it does not take much to cut the high side pressure and you will not know it by cabin temp..
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Old 11-12-2005, 01:25 PM
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thanks will check with gauges as soon as I have time, maybe tomorrow between games
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