help!!.cooling fan not coming on...
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,808
Likes: 0
help!!.cooling fan not coming on...
where is the temp sensor for fan. what is the best way to check this...i don't have my volt meter at this time so i don't know if i am getting voltage at fan...but i just needed to know what to steps to take in trouble shooting this problem.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Re: help!!.cooling fan not coming on... (mikes84vette)
The fan temp switch is located in the right side cyl. head between #6 & #8 cyls. The fan relay is on the inside of the left side inner fender panel, just aft of the wheel area. As you seem to be aware, the ECM has NO control over the fan operation, in an '84. Without a voltmeter or a test light, for trouble shooting, about all you can do is "throw parts at it". That is, except for checking the fuse. Good luck.
Melting Slicks
Joined: Nov 2000
Posts: 3,388
Likes: 1
From: X
Re: help!!.cooling fan not coming on... (mikes84vette)
Does the fan come on when you turn the AC on? If not its the switch on the compressor. You don't have to evacuate the system to change that one.
Burning Brakes
Joined: Sep 2000
Posts: 806
Likes: 0
From: Baton Rouge LA
Re: help!!.cooling fan not coming on... (mikes84vette)
The high pressure switch is in parallel with the coolant sensor. Either one should cause the fan to come on. If not, check the relay or the fuse.
BTW - I wired my manual switch to the AC pressure wire because it was easier to get to. Tie-wrapped it to the harness right behind the compressor, and used the AC mounting bolt for a ground. Works like a charm.
BTW - I wired my manual switch to the AC pressure wire because it was easier to get to. Tie-wrapped it to the harness right behind the compressor, and used the AC mounting bolt for a ground. Works like a charm.
Melting Slicks
Joined: Nov 2000
Posts: 3,388
Likes: 1
From: X
Re: help!!.cooling fan not coming on... (mikes84vette)
1, check the fuse (second row from top...Far right)
2, If fuse is okay, check for voltage to the relay (under break booster)
3, If voltage to relay check coolent temp switch (brown wire) or just replace its only about 10 bucks.
4, If switch is ok or you replaced and it still doesn't work. Turn the car on but don't start it and ground the DARK GREEN with WHITE STRIPED wire at the relay. If the fan doesn't come on check the Fusable link for power at the relay (RED WIRE) if no power repair fusable link.
5, Check AC Pressure switch (TAN WIRE) on top of compressor for power. If there is power at the wire with AC on but the fan doesn't come on the switch is bad and needs to be replaced.
2, If fuse is okay, check for voltage to the relay (under break booster)
3, If voltage to relay check coolent temp switch (brown wire) or just replace its only about 10 bucks.
4, If switch is ok or you replaced and it still doesn't work. Turn the car on but don't start it and ground the DARK GREEN with WHITE STRIPED wire at the relay. If the fan doesn't come on check the Fusable link for power at the relay (RED WIRE) if no power repair fusable link.
5, Check AC Pressure switch (TAN WIRE) on top of compressor for power. If there is power at the wire with AC on but the fan doesn't come on the switch is bad and needs to be replaced.
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Advanced
Joined: Sep 2001
Posts: 87
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From: Baytown Texas
Re: help!!.cooling fan not coming on... (JonM)
Easiest check is to disconnect the plug from the relay and jump the outside slots with a paper clip. If the fan comes on, then it ain't the fan motor, fuse, or fusible link. Get a $4.00 test light and clip the alligator clip to ground and probe the middle red terminal with the key on. If it lights, ok. Then, attach the alligator clip to the positive terminal of the battery, jump the ALDL terminal (as in downloading codes), and with key "on" probe the white/green wire at the connector. The test light should light (the ECM completes the ground).
If all tests ok, then it's a bad relay.
If all tests ok, then it's a bad relay.
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,808
Likes: 0
Re: help!!.cooling fan not coming on... (mikes84vette)
hey check this out. jumpered outer terminals, at relay, fan started. so is this the coolant temp sensor. since it is connected in parallel to a/c hp switch, it still should come if that switch was bad. ruling that out, is there any other thing in series between fan & relay. so is this then a bad relay of temp sensor? :confused:
Burning Brakes
Joined: Sep 2000
Posts: 806
Likes: 0
From: Baton Rouge LA
Re: help!!.cooling fan not coming on... (mikes84vette)
Sounds like the coolant sensor. Remove the connector from the sensor, or the HP switch on the rear of the AC compressor, and short to ground. Fan should start. If not, probably the relay.
