Driving me nuts. Replaced both relays. Tested original fans with direct connection from battery and no go. Replaced with 2 88 IROC fans and tested them before they were put on. They worked so I know the original fan motors were blown.

This all happened when I tried to refill ac with freon over weekend.

I have the original factory manual.

Next will be searching for a short.

I hate electrical gremlins.

 

Make a jumper cable with two male spade connectors and bypass your relays with the battery connected (on my car it's thick ORG and thick BLK/RED). If the fans turn on, you know there's an issue with the circuit that activates the relay. If they don't turn on, there's an issue with the wires going to the fans directly. Or no battery power going to the fans, but that's easy to check as well.

 

Thanks. I replaced both relays. Still nothing. Ordered coolant fan sensor that is between cylinders 6 and 8. Noticed the plug is burned. Also replaced high pressure ac switch and coolant temp sensor in front of engine.

Will let u know how it goes.

 

check for exposed / frayed wirin at the relay connectors...that was my issue.

 

Hey Manny,

What is the problem? Fans not coming on at all, or just not working correctly?

Here is how my 1990 operates - spent some time one day trying to figure out the mystery of how the fans work. What I did was start with a cold engine, and heated it up all the way until thermostats opened, while playing as listed below:

fired her up, turned on the a/c (engine cold) both fans turn on.

turn off a/c, drive side fan remains on for about 1 min, then turns off

turn a/c back on, drive side fan back on, pass side off. about 1 min later, pass side turns on

ac off, temp now 110, turn back a/c on, driver side on immediately, pass side on in about 30 sec this time

ac off, temp now 120, turn back on, driver on immediately, pass side on in about 15 sec

ac off, let temp rise about 220, around 230, driver fan comes on. (seems too late to me in Austin) turn on a/c, pass fan turns on immediately

ac on, temp falls under 220, turn off a/c. pass fan off right away, drive side off in about 1 min

temp still under 220, a/c back on, both fans turn on immediately

 

Not to hijack, but on a cold engine, do your fans cycle when the ac is on? Or are they constantly on?
Also, do they start up immediately once the ac turns on or is there a brief min or so before they come on?

Im wondering if he sees what I see on mine which I attribute to normal operation

 

No need for observational science here; primary fan is controlled by the ecm and secondary fan is controlled by ac high side pressure and the coolant temp switch. For specific activation temperatures, see this thread:

https://www.thirdgen.org/forums/cool...ans-arent.html

 

What I did was start with a cold engine, and heated it up all the way until thermostats opened, while playing as listed above. Read thu that list for the answer, because it depends on what you are doing.

 

I was aware of that. However, its not perfect. The delays I mention are one of the nuances. It doesn't seem to be entirely digital.

 

Straight wired the primary fan today. Oreillys had wrong high pressured sensor I ordered.

Went up to 200 degrees and manually switched primary fan on. Dropped to 185.

Gonna keep it as is until Spring 2022 when I redo ac system.

Good thing the 88 IROC I picked up has the a full engine harness.

I might respice that to see if second fan comes on.

Funny thing is with primary fan connection no codes in ecm since it was unplugged from fan.

Electrical gremlins are not my friend.

Thanks to all.

Knowing me I will tackle it again in a few weeks.

 

In a few weeks, make that jumper cable and connect ORN (+12 Battery) to BLK/RED. It doesn't test the relays; you have to remove them to do it. The results will narrow your problem down to 2 wires per fan, very solvable.

 

Thanks to all. Taking a break from working on it for a week or two. Just got it inspected for $7.

 

I will be back to tackling this issue this weekend.

Thanks to all. Have a 4 day weekend and my dad is in town so we can fix this.

Manny

 

Happy weekend to you too Manny! BTW - I found a place to get an alignment: SoulSpeed Performance. Nice quiet location and they can do it while you wait.

 

Awesome. Thanks. My dad is in town and noticed the shimmy in driving the Camaro.

Ill set up an appointment.

Manny