fan running on start up
Thread Starter
Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
fan running on start up
Just replaced the battery in my 84. Started right up . That's good. However; the rad fan came on immediately and stayed on. Any ideas?
Eric
84 Z51 Auto
05 Repsol Replica
00 TLR 1000
Eric
84 Z51 Auto
05 Repsol Replica
00 TLR 1000
Racer
Joined: Feb 2006
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From: green valley az
Originally Posted by xrcrx
Just replaced the battery in my 84. Started right up . That's good. However; the rad fan came on immediately and stayed on. Any ideas?
Eric
84 Z51 Auto
05 Repsol Replica
00 TLR 1000
Eric
84 Z51 Auto
05 Repsol Replica
00 TLR 1000
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
If there's no fast idle either, troubleshoot the Engine Coolant Temp signal. If the ECM thinks the engine temp is at the threshold for fan operation, it will ground the Relay. Best viewed with a scanner.
Race Director
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From: The Top of Utah
Originally Posted by SunCr
If there's no fast idle either, troubleshoot the Engine Coolant Temp signal. If the ECM thinks the engine temp is at the threshold for fan operation, it will ground the Relay. Best viewed with a scanner.
The fan relay is on the rear, of the left front wheel, inner fender panel, just below the master cylinder and close to the battery. I'll bet you've bumped and possibly damaged the relay, or caused a wire or two to short, when you replaced the battery.
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Drifting
Joined: May 2005
Posts: 1,370
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From: Raleigh NC
Originally Posted by robertt43
Was the air switched on? A/c cont turns fan on immediately! Could be bad relay,you sent extra jolt thru system,and contact points stuck inside relay.You can take the cover off the relay,and watch how it works.My 84 had problems with the brown wire coming from the temp switch,it was broken when someone pinched the wires doing a emmission test with the clamp they hook on,they have to open the harness,[left rear of blk,clipped to the pan,underneath the car].
Turn your AC off. Your AC will automatically turn on after disconnecting the battery if you have climate control.
Thread Starter
Burning Brakes
Joined: Feb 2006
Posts: 1,098
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From: Webster Texas
first chance
This is my first chance to check back. thanks all for the input. I'll have to check the things y'all have noted. I did drive the car today, briefly. The A/C is always turned off when I stop the car. The fan runs whether I have the A/C on or not. The car ran at it's normal temp when I drove it and the A/C blew cold when I turned it on. There is a plug-in on the back of the A/C compressor, not the multi-prong but the one that is a metal tube , very small, surrounded by plastic and covered in rubber. It seemed a bit loose and when I unplugged it some broken plastic fell off-any connection here? Thanks again!
Eric
84 Z51 Auto
Eric
84 Z51 Auto
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Racer
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From: green valley az
Vacuum
Originally Posted by xrcrx
This is my first chance to check back. thanks all for the input. I'll have to check the things y'all have noted. I did drive the car today, briefly. The A/C is always turned off when I stop the car. The fan runs whether I have the A/C on or not. The car ran at it's normal temp when I drove it and the A/C blew cold when I turned it on. There is a plug-in on the back of the A/C compressor, not the multi-prong but the one that is a metal tube , very small, surrounded by plastic and covered in rubber. It seemed a bit loose and when I unplugged it some broken plastic fell off-any connection here? Thanks again!
Eric
84 Z51 Auto
Eric
84 Z51 Auto
Race Director
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From: The Top of Utah
There are no vacuum hoses, vacuum connections, or vacuum monitoring devices that affect the running of the fan. The fan is a simple, electric, device, powered through a simple relay. There are no sensors, ECMs, processors, or electronics of any sort used in the operation of the 1984 cooling fan. The grounding of circuit# 335 closes the primary circuit of the fan relay, sending power to the fan motor. Circuit# 335 can be grounded in two places, by design. One place is at the temperature switch in the right side cylinder head, and the other is at the switch in the rear of the A/C compressor. Xrcrx. If any of what has broken at the back of the compressor allows the tan wire in a single wire connector to ground, that will cause the fan to run.
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Thread Starter
Burning Brakes
Joined: Feb 2006
Posts: 1,098
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From: Webster Texas
more info
The switch on the back of the A/C compressor is a small tube-the plug in is a small pin. When it's plugged in the fan immediately comes on when I start the car. If I unplug it the fan goes off till the temp reaches 124, then it comes on. lkill the car let it cool. Restart with the pin unplugged, the fan stays off till 124 degrees then kicks. Kill car let it cool. Plug back in. Turn on key but don't start-fan comes on. There are 2 switches on back of the compressor, one is pronged similar to a wall plug, the other is a pin that plugs in a copper "tube" on a "switch" on the compressor-this is the one I'm speaking of. My guess is this switch is supposed to kick on the fan w/the A/C compressor as it is otherwise functioning OK. Thanks again to all.
Eric
84 Z51 Auto
Eric
84 Z51 Auto
Burning Brakes
Joined: Nov 2005
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From: 1992 LT1 6 speed Cayman Islands
Check to see if this plug is somehow grounding on the compressor body where you say the insulation fell off. If it is not grounding on the wire then you need to replsce the switch unless your AC system is way onercharged as this switch is activated by preassure.
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From: Milpitas ca
Originally Posted by CFI-EFI
The fan relay is on the rear, of the left front wheel, inner fender panel, just below the master cylinder and close to the battery. I'll bet you've bumped and possibly damaged the relay, or caused a wire or two to short, when you replaced the battery.
RACE ON!!!
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Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by xrcrx
When it's plugged in the fan immediately comes on when I start the car. If I unplug it the fan goes off till the temp reaches 124, then it comes on.
Eric
84 Z51 Auto
Eric
84 Z51 Auto
If your fan is coming in at 124° Centigrade, it is about right. If that is 124° Fahrenheit, that is over 100° cooler than stock and too cool for any purpose. If so the switch in the right head should be replaced, too. You may want to do some shopping on the head switch, as it is set to start the fan at about 235° F. An on temp of somewhere between 205° and 215° would help the engine run in a better temperature range.
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Thread Starter
Burning Brakes
Joined: Feb 2006
Posts: 1,098
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From: Webster Texas
thanks!
CFI-EFI and all: thanks for the help. CFI: that is the switch that seems to be defective. I misposted, my fan comes on at 224 F. I drove the car to work. Summertime is here in Houston. Ran the A/C, had no overheating issues. Temp ranged from 179F-185F w/the A/C running in traffic. I'll be picking up the switch in the next few days, let y'all know how it goes. Thanks for all the help.
Eric
84 Z51 Auto
Eric
84 Z51 Auto
