I took my 87 into the shop to have the differential serviced, (routine). The tech noticed that the cooling fans aren't coming on.
What could be the cause of this?
Is this one going to cost me big?

 

more than likely it's just the relay. Located on the left inner fender well. Around $12

 

Easy to diagnose, and replace?

 

Cooling fans not coming on can become a serious problem very quickly if you get stuck in traffic very long.......even in this cool weather I am suprised the tech didn't stress this issue(or perhaps he did?).....

I wonder why he thought the fans should have been on in the first place? My initial impression is that you first need to confirm the tech is actually correct....

Could be several causes, but I would agree the top candidate is probably the relay....

 

The car is new to me. I asked them to look it over. They said they didn't have time to correct the issue, and I could pick it up, or leave it. If it's not a big job, I'd like to do it myself.

 

Dale- Depending on the outdoor temperature where you are at this time of the year the engine may just be not be reaching the temp where the fans are needed.
OEM radiators are sized to maintain 180 to 195 F over 35 mph . The OEM fan settings turn the main fan on at 228 F and the auxiliary fan (if you have one) at 238 F. GM says to shut the engine off at 260 F and let it cool down. I just thought I'd mention it as you said you weren't familiar with the car. When I first had got my car I thought the fans were defunct as they rarely came on.
You might want to use the Search at the top of the page and look through the archives for troubleshooting fans.

 

 

I'm certain the fan isn't working. First, the guy working on the car is a vette savvy tech. Not a vette specialist, but works at an independant dealer who is also a collector, (has a sweet 68 c3 vert. w/427 in his collector garage). Bottom line, I trust the guy.
Second, I looked at some stuff, turned on the ac, no fan. Checked the fuse, it's good.
Here's where I am... I know concepts, but I know nothing of a vette. The documentation mentions the ALDL port? Is that the block under the driver's wheel? I guess I need a little bit of hand holding to start off here.
The darn relay is cheap enough and easy enough to get to, I could just buy one and pop it in, but then I wouldn't learn a darn thing. So, I'm trying to learn on something that isn't the most critical component.
Speaking of relays... eckler's has a "conversion" kit to convert to '88 and up standard relay? Is that worthwhile? It's like $19 versus $14 for the '87 relay.

It was actually a good news / bad news kind of thing. First they call me, tell me the car will be done in about an hour, and the tech said it's one of the cleaner '87s he's seen, no leaks, no obvious lurking problems. Great. Then, about 20 minutes later, I get the call that the fan is an issue. Isn't that how it goes with all cars?

Thanks in advance for any help or advice.

 

I agree make sure the tech is correct and the fans/s are indeed not comming on when the car gets to 230. Most cars do not run anywhere near this hot and him having an old Corvette and being a great tech he still may not be all that familiar with the C4. The other thing to look for is see if the car has a toggle switch somewhere, there is a manual fan switch sold for these cars and that may be your problem. After this I would buy a new relay, it's cheap enough to just buy a new one and eliminate it as a possibility.

 

The fan, it's an 87 it only has one, should come on when the AC is turned on as well.
As for a manual switch. I highly doubt it. This car is bone stock. No indication anyone did any kind of messing with it.
I have the electrical troubleshooting supplement. I'm checking it out, but it assumes you know some things, I don't know. One thing they want you to have is a fused jumper. I don't have any.
I guess I could just buy the relay, but I was hoping to actually troubleshoot. Guess I need some more test equipment?

 

1) Does your AC actually work????

2)You can easily make a fused jumper.......Go to Radio Shack or autoparts store and get a fuse holder, a fuse and couple of alligator clips.......splice on some wires of appropriate size & length to the fuse holder...attach alligator clips and you are ready to go...

Good luck....sounds like you got a really nice car

 

The fact that your car is a 87 does not tell me how many fans it has.
There were 20,281 1987 Corvettes with R.P.O. BP4 which was the auxillary fan. It was standard with the Z51 suspension or a $75.00 option. Your fan should come on with the AC providing it is working correctly. A manual fan switch is not a big deal or a big mod and after 20 years it was worth a quick look. I was thinking just maybe your car had a toggle under the dash and you didn't know what it was for.
Step one, get the car up to temp, see if the fan comes on and report back.

 

Didn't know that, thought I read where '87s only had one. Ok, I don't have BP4 as one of my RPO codes. It's definately not a Z51. If it has a manual switch they hid it pretty well.
I tried to get the AC on... it was 50 outside, and it's got the climate control. I put it to 60... I don't really think the compressor kicked on.
I've seen it quoted a few times, 228* is where it should come on? I'll get it hot today and verify. And work on making a fused jumper.

 

The AC is a mystery to me. I have climate control, and I bought this thing in the last month. I haven't been able to force the AC to come on. That's one thing that could be lurking for me.
Making a fused jumper sounds easy enough. I was thinking about that last night.

I think I did ok on this car, with lots of help from this forum. I'm finally starting to get some confidence in the car. The good news is I can still drive it, I just have to be careful until I get this resolved.

 

hey dale if you look at ac comp you should be able to see clutch not turning when ac is off then go and set control at 60 and hit the ac button you should then be able to see the clutch turning or not turning if its turning it should work unless its low on freon

 

Turn the fan blade and make sure the fan motor isn't binding.

The fan relay should be mounted on the black plastic drive side wheel well housing towards the back of the front tire.

I'm looking at the schematic from a 89 so the color of the wires maybe different.

The relay has 4 wires. Two of them are a heavier gauge than the other two.

The large Red wire is hot at all times and is 12 volts. It comes from a fusible link. When the relay closes, 12 volts is transfered from the Red wire to a Black/Red wire which goes to the fan motor.

The two small wires control the relay. A Dark Blue wire has 12 volts on it when the ignition key is in run or start.

The Computer closes the relay to turn on the fan by grounding the Dark Green/White wire.

You can force the fan on by shorting pin A to B on the Diag. connector located above the drivers knee area. Use a paper clip or piece of wire. Short the pins together and turn the ignition key to run.
(No need to start the engine). The fan relay should energize and the fan should run.

Diag. connector looks like this.

[F|E|D|C|B|A]
[G|H|J|K|L|M]

When you short pin A to B and turn the ignition on you'll also hear a ticking noise around the throttle body area, that's the IAC being forced closed. That's normal.

 

AC should come on in the defrost position......at least under certain conditions.....

BTW another good test tool is an inexpensive voltmeter/multimeter...even one under $10 works well to chase down 12vdc..

 

I bought a light because they're so easy to use, (simple light versus trying to read an lcd display). I have a very good DMM left over from my "other life". My degree is in electronics, believe it or not, and the DMM was my friend. I've been doing computers for about 15 years now, so my electrical/electronics knowledge has turned to mush!

 

First thing I did was turn the fan. Turns free and easy.
That's all very good info... I'm learning, slowly, but I'm learning. I'm going to have to print this all out, my memory isn't what it once was!

 

Hey Geo, thanks for the info, I'll give that a shot.
How's the car sale going?