I have an 86 Iroc 305 TPI, its got 66K original miles. Has an overheating problem gets really hot in stop and go traffic but stays cool at freeway speeds. I noticed that the fan never comes on. I replaced the relay and no luck. Even when i turn on the AC the fan doesnt come on. What do i have to do to test the fan. I need to know in detail im not a very good mechanic.

 

normally when you put the AC on, or you do the paperclip test.
(the 1 to read out your computer ) your fan should come up.
the most logic thing to do next is take a voltmeter and start measuring your voltage from the fan wiring.
1) do you get power from the battery to the fan relay ?
no = no power to fan relay wire = cut/broken or whatever, fix wire or make new wire.


2) do you get power from the ecm to the fan relay ( when fan is requested ) do the paperclip method to read out your ecm this makes shure your fan is requested by the ecm.
then measure the wire from the relay to the ecm.
if bad, something is wrong with the ecm or the wiring.
if its good, something is wrong with the relay itself or the wiring from the relay to the fan. or the relay to the ground, or the fan itself or the fan to ground wiring.

anyway, you need to make shure what is and whats not the problem.

but probably your problem will be the relay itself is faulty.
you should here it click when the fan is requested.

 

which relays EXACTLY control the fan, i know the one by the radiator, and i dont know where the other one is, on the driver side firewall but theres 3 there which one is it? Even when i replaced the relay on the radiator i never heard clicking or anything.

 

wel, 1 out of those 3.
I know 1 other is from your fuell pump.
the 1 from your fan should have a

orange, black red and purple wiring going to it.
red is hot @ all times.
orange = hot when fan is requested by ecm or air conditioning,....
black = ground
purple goes to your fan.

if you would disconnect the connector from the relay and you run a wire from the + of your battery to the purple wire. and the fan comes on, you know that the fan itself is OK.

 

so disconnect the connection from the relay and take a wire from my battery to the purple wire and the fan should come on?

 

yes ( but do use a big enough wire )
normally your fan is fused on 30A. if you run that trough a small wire it will heat up the wire and burn out. ( no good for anyone )

 

so what does it mean if the fan comes on or if the fan doesnt come on?

 

if the fan doesnt come on, the problem is on of the following
a)the purple wire to fan
B) the fan itself <= biggest chance )
C) the ground wire from the fan to the chassis or battery.

if the fan does come on your problem is
A) the relay itself <= most likely
B) the red wire that doesnt get power ( needs to be 12V @ all time ) ( could be if the fusible link is burned trough )
C) the ground wire from the relay to the battery
D) the orange wire from your computer to relay that doesnt pass the signal to the relay
E) the computer itself

 

the fan came on, i ran a wire from the battery to the red wire going into the relay next the radiator, all the wires on the firewall in the firewall relays were all diff colors from what they are at the radiator. I tried the new relay in all of them and made no differnce and turn the AC on and the fan doesnt come on.

 

My signature has fan diagnosis. Although it's for dual fan cars. You may find some info in it though.

 

AC on maximum AND engine running ?

 

The red wire going into the fan relay is a power wire from the battery to the junction box and through the fusible link to the relay. If you jumpered that wire at the relay and it worked, either the fusible link is burnt or the integrity of the wiring from the battery to there or one of the connections is the problem