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C4 cooling fan problems please help

 
Sinxb
I love my Chevy Chevette!
Posts: 3
Joined: 04/11
Posted: 04/24/11 07:20 PM

84 C4 I have replaced the Sensor on the drivers side front head, the switch on the pass side head, and replaced the relay but still my cooling fan will not come on.
I have seen the fan run since i have tested using various methods found on the web to test all the parts. I have added a diagram I found on this site and need to know where the hot at all times fuse link runs to and where the fuse actually is. This lead is not hot when the car is off or when it is on. I tried to trace it but lose it fast in the harness. I don't like my Vette running so frickin hot.


84 C4 Radiatorcoolingfanwiring

Any help in getting my car to run cool would be great thank you.  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/24/11 09:00 PM

the diagram above is just for the 84 cross fire motors...

the 85 and newer have a slightly different system...

can you verify exactly what year your corvette is...  

some of the diagrams i have posted are larger than can be seen in this forum..  so you might have to open the image in a new window to see the total diagram.. or the second version to the right..


the cooling fan switch or the AC pressure switch connect to ground to activate the relay when the ignition is on....

this is the radiator cooling fan switch..    notice it only has a SINGLE contact down the middle..  

Radiatorfanswtichtopview

Radiatorfranswitch S500sideview

this is the proper connector shape for the cooling fan switch...

Radiatorcoolingfanconnector231

to test the circuit...   turn the key on..   unplug and ground the terminal.. the fans should come on...


i have found the cooling fan relays bad...  the cooling fan relay harness connectors melted.. and the radiator cooling fan motors bad...

verify what year you have... i will try to get you the proper repair info...

you might also want to pick up a duralast / or wells SU102 from autozone...  only some of the stores keep it in stock.. but all can get it with a the part number... comes with the Engine coolant temp sensor and the connector... change both ...  does not matter which way to crimp the wires on..  the engine coolant temp sensors fail..   the coaxial type on 82 and 84 models were horrible..
they tell the computer how hot the engine is to set the fuel ratio....  the temp signal from this is critical for the cooling fans to operate on 85 and up..  but all the early C4s can use this upgrade...

Su102

post what year... and if you have grounded the wire... and been able to cycle the fan on...


the radiator fan relay is usually near the brake power booster.. on the inner fenderwell... drivers side....

if you have a 85 or newer.. PLEASE do NOT probe the wires from the computer to the cooling fan relay..  you won't like the results...

these cars also have to have a 192F thermostat...  and a radiator cap that actually holds pressure..  some have center discs that flap.. they don't hold pressure properly..   and 50/50 to 70/30 .. coolant to water ratio...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/24/11 09:12 PM

84 diagram...  if you look at this diagram for the 82 and 84 crossfire fuel injection system..   you won't see any radiator cooling fan controls listed...   they were separate on these models..  



84Vettecrossfireenginelocations  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/24/11 09:25 PM

the radiator cooling fan relay...



 

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Sinxb
I love my Chevy Chevette!
Posts: 3
Joined: 04/11
Posted: 04/25/11 11:39 AM

I did say it is an 84 C4. I have replaced both the sensor and the switch. I also replaced the relay near the battery. on your diagram the #1 pin should be hot at all times and it is not. I did also replace the thermostat with a 195 first thing.
The only sensor I have not replaced is the one screwed into the front of the intake manifold which near as I can tell is what is telling my gauge to display which works fine. it runs up to 240 with no fan coming on. I read that the fan should atleast come on at 238 I let it go past that a couple times testing. 245 is the highest I have let it go.  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/25/11 01:07 PM

84  great... i totally missed that..

do you still have the old cooling fan relay...   pry the cap off... so you expose the open relay...    plug the harness into it.. using care not to short the exposed frame o the relay to ground...   squeeze the contacts closed... does the radiator cooling fan turn on?????

in looking at the contacts... looks like you could use a male quick connect terminal on the ends of a short piece of wire...  jumping the 1 and 4 terminals and the fans should come on...


the dark blue wire should ONLY have power when the key is in the run and start position...

the dark green with a white stripe wire at the relay if you add a wire to it.. and you ground that wire... that should operate the relay and turn the fans on when the key is on...

i would like you to test the circuit automation by leaving the key on.. and shorting the single wire between the last 2 spark plugs on the passenger side of the engine to ground...   that should operate the relay..

there is a 2 wire  connector on the back of the air conditioning tubes behind the compressor.. where you can also ground it... and make the fan come on when the key is on...  

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Sinxb
I love my Chevy Chevette!
Posts: 3
Joined: 04/11
Posted: 04/25/11 06:32 PM

I will try that pulling the relay apart and see if that works thank you.  

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