Good Day, My family has a 1988 Camaro Iroc since new and it has 16,300 original miles. I learned these engines were designed to run hotter than the old camaros but I am finding if the car is moving temps seem good. As soon as you get stuck in traffic quickly climbs to 220F or slightly higher. The driver side fan kicks on when I turn on the A/C. I have not noticed the passenger side fan turning on at all. I disconnected each fan and ran a jumper cable to a 12V battery. They both work. My manual says the fan does not kick in until temp reaches about 240F. If correct, that makes me feel uneasy. Many say to replace the temp switch on the passenger side that screws into the block. Is there a way I can tell if switch works first since I can barely see it and dont wish to have antifreeze coming out of the block to remove it. You-Tubers who replace this swtich suggest one that activates 10-15 degrees sooner to avoid getting too hot. Anyone do this and what part is it so I can source it out. Also need part number for the OEM switch in case I keep it factory.

Thanks for your help.





A second thought is to check the relay for that side fan. Can anyone tell me which relay it is and how to check to see if that working.

 

Nice looking car. Sounds like you're trying to fix a problem that isn't there, but I also "get it" that it makes people uncomfortable to see such high temps.


1. Why not simply unplug the driver's side fan to prevent it from running and allow the engine temp to rise to that point?
2. You can swap the old switch with a new one quickly, if you have it ready to go and handy, and only lose about a 1/2 cup of coolant, or so, if you're quick.
3. I have run lower temp switches...but that was 25 years ago. I have no idea what the part numbers were. I found the switches w/the temps that I wanted by thumbing through parts books that showed temp switches' specs. You could do that much easier today, on line with search filters, etc.

 

These cars ran hot from the factory for emissions purposes. 1st time mine hit 240 I freaked out.

 

Absolutely, I am used to the cars from the 70's where 210F was hot. At some point I will have to get back from a ride and let car idle in drive way and watch to see if primary fan kicks on. I will have an infrared thermometer handy to see what kind of readings I get. If it does not kick on then I have to find the right relay and get a new switch for the engine. In the meantime will check boiling point of exisiting antifreeze.

 

Thanks I hope you are right. I hope there isn't a real issue but I am used to older cars running at 195F. This was my brothers car before he passed this summer and I now have it and have to learn about all these relays and other things.

 

Yeah 220f with no airflow isn't crazy in these cars. Check out the fan switch for a 1987 Buick Grand National, I think the activation temp is somewhat lower like 225f. The swap out isn't too hard of a job. If the coolant is old, that would be an ideal time for a flush (block drains included).

Edit: Highly recommend purchasing the factory service manual for your year. It has diagrams for finding your relay and troubleshooting your system.

 

We have so many here that are not sure if their fans are working correctly, so I decided to run this test a while back. keep in mind, this is for a 1990, an 88 may operate a bit different, but I'd think it would be at least analogous to this.

https://www.thirdgen.org/forums/cool...ervations.html

 

This should help answer, "How it works"....




And to answer one of the OP's original question, the cooling fan relay is on the right side of the radiator, and on the right front fendet. See figure.

 

Thanks everyone. Learning slowly with all these relays, wires, temp switches etc. I was first checking yesterday the boiling point of the existing antifreeze and it was 263F. That was good. Trouble was when I removed the original radiator cap it literally came apart in several pieces. Since this used to be my brothers car I had no idea when or if this cap had ever been off for any reason before so new replacement factory cap on order. Will try to source out a NOS cap because the new ones RC27 by A/C Delco have this weird label covering the top of the cap. i dont like the look. .
Taking a step back just to ask this question ......with 2 fans which is the primary cooling fan and which is the secondary cooling fan before I will re-attempt to retrace all wires. My driver side fan at some point kicks on but I have never seen the passenger side ever kick on but I know both fans work since I hooked up each one a few weeks back with a 12V source. If the passenger side is linked to the A/C and its charge is low will that prevent fan from turning on when A/C is turned on from the dash ? Like others have said maybe I am chasing a problem that does not exist but until I see both fans running with my own eyes I will trust but keep verifying that all is okay.

My next step is to test the relays out of the car to see if they click open and closed with a 12V power source.

 

If you look at the drawing that I shared, you'll see that one fan is labelled, "Coolant Fan Motor". The other fan is labelled "Heavy Duty Coolant Fan Motor".

To ME, that tells you right there: The "Coolant Fan Motor"....would be your primary fan, "HD CFM" is your secondary.


As for testing relays, WHY?? What you really want to know is: Do both fans run? You could prove your relays both work, and still have a non functioning fan. You already know that one fan runs. disable it and see if the other comes on. If it does, your relay is working. And your fuses, wiring, connectors, sensors/switches, motor, etc. etc.

 

For me to verify proper operation of both fans, all I need to do is turn on the a/c (see above link) I always assumed my driver side fan is primary since it is usually on first.

 

Normal operating temps are 200-245. Second fan kicks around 238degs. Normal.
Key on, engine off.
Unplug the switch in the pass head.
Simply run a ground wire from the connector pin to a metal spot on the engine. The pass fan will run if everything else is fine. You're just grounding the relay without the switch.
To change the fan temp switch, remove radiator cap, put a slight vacuum on the cooling system, then R&R the switch without coolant loss.
Don't overthink these cars, they are very simple.

 

From the pic I could not tell where the orientation towards the front of the vehicle is pointing. I assume by your reply front of vehicle is on right side of wiring diagram. Correct ?

 

Good info - thankyou.

 

The Front of vehicle is "south east". Pointing toward the bottom, right. You can see the bottom of the fans, the intake snorkel, alt/ac, TB, runners, wheel well in the pic, for orientation.

 

You can check the auxiliary fan and its relay in 2 ways.

1. Jumper the AC fan switch connector. Unplug the two wire connector on the AC hard line, located between battery and strut tower (it faces straight up and down). Inside the car, set AC on and start the car. Outside, use a paperclip to jumper the plug, momentarily. This can prove the aux fan relay and fan motor are good. Actually, both fans should run with this test on your 88 TPI.

2. As TTOP350 already commented above, ground the aux fan switch connector. (Smaller of the two single wire connectors). This can prove wiring, 2nd fan relay, and motor are good.

I imagine if your AC, or AC fan circuit, isn't working, then modifying this switch is more important, since you only have 1 fan working most of the time. If they worked the aux fan would come on more often.

If you decide to get a colder switch-- Beware! New switches can be bad / wrong spec out of the box! If you suspect bad part, use test 2 to prove wiring up to the switch is good.

I've had an ac delco go bad after couple years, NAPA waaay out of spec, etc. It's basically a lottery at this point from any manufacturer, it seems.

For a couple years I have been using this switch: murray 35946 (o'reilly). Like mentioned above, that's an 87 Buick GNX turbo part.

Also know that the connector is probably going to crumble when you disconnect it. You can buy a replacement and splice it OR gently repin it for a factory look. I use an inexpensive Lisle wire terminal tool.

Beautiful car and good luck! Hope this helps.

 

Maybe my 2 cents will help others:

So today a new radiator cap was installed and car was left to idle for 25 minutes. Dash gauge showed above 220F after 25 minutes but at no time on the engine did we observe with an infrared thermometer temps above 180-190 and upper hose showed even lower temps so we safely assumed the 195F thermostat did not open yet. Thermostat housing, intake manifold, and top of engine temps were never above 195F so we did not believe also the thermostat was stuck closed. Primary fan was kicking on and off so everything there appears to be working fine.

One could perhaps rationalize that the dash gauge is not very accurate relative to the true engine temperature throughout because the temperature switch and sensor that drives the dash gauge sits lower on the engine close to the exhaust manifolds therefore these parts experience a hotter temp earlier than the areas on top of the engine where the thermostat is located especially with the hood open. The result is your dash is showing 220 – 230 but the 195 thermostat hasn’t even opened up yet. My take away is that when I am sitting in traffic I will not be as concerned as I was a few days ago.

PS: I did have A/C running and that second fan still did not kick on only because I believe the engine simply did not get hot enough during the 25 minute idle.

 

I just wanted to correct this since I haven't seen it mentioned yet in any of the replies.

The cooling fan switch is in the right passenger side cylinder head located between cylinders #6 & #8 and not in the block on the passenger side. The thing in the block on the right passenger side is the knock sensor. The knock sensor screws into the passenger side engine block drain. On the driver side in the same place is the other block drain. I just don't want you unscrewing the knock sensor by mistake if you decide to change the cooling fan switch.

 

I dunno about that...the fan comes on regardless of temp. AC on and head pressure above 233 psi should make it run. Both fans should work with the AC...

per 88 shop manual:
"In the V8 VIN F and the V8 VIN 8, the Heavy
Duty Coolant Fan is controlled by the Heavy
Duty Coolant Fan Switch and Fan Pressure
Switch. With the Ignition Switch in RUN, bat-
tery voltage is applied through the FP FAN
Fuse to the Heavy Duty Coolant Fan Relay coil.
When either switch closes, the Heavy Duty
Coolant Fan Relay is energized and its contacts
close. Battery voltage is supplied to the Heavy
Duty Coolant Fan and the fan comes on."

 

@i88aGT Since it seems you have the 1988 shop manual can you post the ECM controlled primary cooling fan turn on & off temperatures and the HD cooling fan switch turn on & off temperatures?

I'm sure the primary fan's turn on temperature is well above the 180 to 190 degrees he was seeing with his laser temperature gun.

 

Absolutely--

Heavy Duty Fan on at 238°F. (Normally open cooling fan temp switch). Ckt 731 gray. Runs to ECM D11 and also secondary fan relay.

Primary Fan on at greater than 223°F. (CTS). Totally controlled by ECM grounding primary fan relay. Ckt 335 dk grn/white. ECM can remove this ground "if vehicle speed is over 40mph unless engine is overheating." Also, the normally open fan control switch (ac pressure switch) will cause ECM to ground CKT 335. Closes at 233 psi, opens at 185 psi.

I also have access to the supplemental shop manual, which includes test charts for heavy duty fan...