Why won't my cooling fan come on??

[Rockabetty78]

I have a 2013 LT hatchback 1.8l. The cooling fan's not turning on when it should. I got a trouble code P0128 So I replaced the thermostat. Fan still does not turn on when it's supposed to. I checked to see if the fan itself was working by connecting it directly to the battery and it does work. I checked the fuse box and pulled the relay that was labeled for cooling fan and swapped it with the one for the windshield wipers to see if it was the relay that was faulty. The windshield wipers worked but the cooling fan still did not come on when it should. But I've been reading conflicting information as to which relays are the cooling fan relays. I pulled the big gray relay 2nd up from the lower right hand corner of the fuse box. I was working my way from the fan to the fuse box checking the components to see where the fault is but now I'm pretty confused and not even sure if I'm doing this correctly. I need guidance please!

 

[orangeltz13]

There may be a temperature sensor in the fan that has failed open keeping the fan from turning on. If the sensor is not a part of the fan it has to be connected to the circuit somewhere between the fan and the fuse or relay. I would check those 2 items.

 

[orangeltz13]

I have a 2013 LT hatchback 1.8l. The cooling fan's not turning on when it should. I got a trouble code P0128 So I replaced the thermostat. Fan still does not turn on when it's supposed to. I checked to see if the fan itself was working by connecting it directly to the battery and it does work. I checked the fuse box and pulled the relay that was labeled for cooling fan and swapped it with the one for the windshield wipers to see if it was the relay that was faulty. The windshield wipers worked but the cooling fan still did not come on when it should. But I've been reading conflicting information as to which relays are the cooling fan relays. I pulled the big gray relay 2nd up from the lower right hand corner of the fuse box. I was working my way from the fan to the fuse box checking the components to see where the fault is but now I'm pretty confused and not even sure if I'm doing this correctly. I need guidance please!

Also. this is what I found online: https://s3.amazonaws.com/rp-part-images/assets/4e06ac3dcbd25fc059a38558baa06d6a.jpg

https://www.gmpartsnow.com/oem-part...9c29uaWMmeT0yMDEzJnQ9bHR6JmU9MS00bC1sNC1nYXM=

The sensor provides the ECM with the temperature of the engine. The ecm turns the fan off/on based on the temperature it is provided. If your fan operates when connected to a power source and you have checked the fuse and relays, I would say the next component would be the sensor. You could also monitor the coolant temperature by plugging an OBDll reader device in the plug underneath the dash on the driver-side. These devices are cheap and the software is free. I use one when I have to drive long distances. This is what I use: https://www.amazon.com/Scanner-Vehi...ac-be5c-e8b91692950d&pd_rd_i=B076FRK5BT&psc=1

 

[Rockabetty78]

I replaced the thermostat housing which came with new temperature sensors. I have an obd2 scanner. How do I check the coolant temperature with it? Also, I'm not sure I checked the relays correctly… I have a multi meter, I'm still not quite sure how to use it though.

 

[orangeltz13]

I replaced the thermostat housing which came with new temperature sensors. I have an obd2 scanner. How do I check the coolant temperature with it? Also, I'm not sure I checked the relays correctly… I have a multi meter, I'm still not quite sure how to use it though.

It depends on the obd2 scanner. I had to download/install an app to my phone. Then I had to go into the menu and choose a parameter to measure. The first one I chose was the coolant temperature parameter.

 

[SuperS13]

So have the same problem with my 1.8L, I even have a new dorman radiator fan unit. Where would the relay be for the radiator fan assembly and the coolant temp sensor relay?

 

[Von]

I'm here for the same reason. 2013 1.4 turbo.
My niece hit a big turtle in road and the AC stopped working, among other damage that I've already fixed.
I've replaced the bent condenser, leaking line from condenser to compressor. It will hold pressure but compressor wont kick on. I noticed the cooling fan wasn't coming on while it was sitting in the shop running, thinking the fan not coming on is keeping the AC from working.

 

[Von]

I also jumped power to the fan, to the 87 pin on the fan3 relay, and it comes on.

Looking at the wiring diagram I found online, it shows two coolant temp sensors. Sensor 1 at rear of block and sensor 2 at lower right of radiator.

I'm going to try ohming out the wires between sensor 2 and the ECM, maybe the turtle caused a break somewhere.
While I'm doing that...
Is there a way to test the sensor to see if it works, other than seeing whether or not the fan comes on? Continuity test or something?
Id rather not replace #2 and find out #1 was bad.

I've also read elsewhere that if the temp sensor if bad the ECM will use an ambient temp sensor as a backup, but that may have been for a different function. Not sure, I read WAY too much and might have my wires crossed on that.

I'm ready to get this thing out of my shop... My stepson has already paid me for it. I think he's going to trade it off on a motorcycle or something. He thought I'd be upset about that.. NOPE. If he trades it off it won't be in the family anymore and I'll never see it again.

 

[Torianiece]

Von, did you figure out the problem? I got into a wreck and my car is doing the same thing, I was going to purchase a service manual but can’t find one online

 

[Von]

Von, did you figure out the problem? I got into a wreck and my car is doing the same thing, I was going to purchase a service manual but can’t find one online

The ambient air temp sensor was completely missing, ripped from the grill, wires loose.
I replaced the sensor and the AC compressor will now come on.. until the engine gets hot. The fan still won't come on.

We found a service receipt in the glove box from when my niece had it in the shop. On it he states that he thinks the main fuse box is bad.

 

[Torianiece]

If the main fuse box is bad how can you tell?

 

[Torianiece]

Also do you know where I could purchase a wiring diagram or repair manual?
Will the Cruze repair manual work?

 

[Torianiece]

Do you know if the ac has a high and low pressure sensor?

 

[Von]

I just pulled the fuse box apart and put it back together hoping it was a bad connection. No change.

The fuse box is just a big holder for the fuses and relays and there's 3 big harnesses bolted to it from the bottom and plugging the harnesses into the fuses and relays. I'm guessing if it's bad that means connectors have moved and connections aren't being made.

There's a sensor on one of the lines going into the front of the compressor, don't know if it's high pressure or low or if there's another sensor. Sorry.

I don't remember where I found the 2 wiring diagrams I downloaded, but they weren't much help. If I find the links again I'll post them.

I tried swapping fan relays again.
There's 3 fan relays. 3 speeds.
Relay 8, cool fan K3
Relay 7, cool fan K2
Relay 13, cool fan K1
A LOT of guessing coming up.
I'm guessing K3 is high speed and is supposed to engage when the AC is on.
I swapped all 3 around. All 3 went into the socket for K3 with little resistance. Maybe not connecting good.
The engine was running at the time . I thought I felt the relay click on a couple of times while inserting it but the fan never came on.
I'll take the box back apart and check connectors for that socket.

I'm going to telly stepson that IF I get it fixed he needs to SELL ASAP.
He works in the oil field and wants to drive this POS to work instead of his Tundra. This car won't last a week if he takes it out there.
I'm warning him, once this thing leaves my shop I never want to see it again.

 

[Von]

I just pulled the fuse box apart and put it back together hoping it was a bad connection. No change.

The fuse box is just a big holder for the fuses and relays and there's 3 big harnesses bolted to it from the bottom and plugging the harnesses into the fuses and relays. I'm guessing if it's bad that means connectors have moved and connections aren't being made.

There's a sensor on one of the lines going into the front of the compressor, don't know if it's high pressure or low or if there's another sensor. Sorry.

I don't remember where I found the 2 wiring diagrams I downloaded, but they weren't much help. If I find the links again I'll post them.

I tried swapping fan relays again.
There's 3 fan relays. 3 speeds.
Relay 8, cool fan K3
Relay 7, cool fan K2
Relay 13, cool fan K1
A LOT of guessing coming up.
I'm guessing K3 is high speed and is supposed to engage when the AC is on.
I swapped all 3 around. All 3 went into the socket for K3 with little resistance. Maybe not connecting good.
The engine was running at the time . I thought I felt the relay click on a couple of times while inserting it but the fan never came on.
I'll take the box back apart and check connectors for that socket.

I'm going to telly stepson that IF I get it fixed he needs to SELL ASAP.
He works in the oil field and wants to drive this POS to work instead of his Tundra. This car won't last a week if he takes it out there.
I'm warning him, once this thing leaves my shop I never want to see it again.

Well.. the fuse box is more then just a fuse holder... A circuit board, 6 big chips, a plethora of smaller chip things and a bunch of prongs for everything to plug into.
I have no idea how to test the chips. The top of the board looks okay. I'll see if I can get the board and look at the bottom.

Tried to post a pic, too large. Cropped screenshot too large..
What's the file size limit on this website?

 

[Von]

Well.. the fuse box is more then just a fuse holder... A circuit board, 6 big chips, a plethora of smaller chip things and a bunch of prongs for everything to plug into.
I have no idea how to test the chips. The top of the board looks okay. I'll see if I can get the board and look at the bottom.

Tried to post a pic, too large. Cropped screenshot too large..
What's the file size limit on this website?

Far out man, that worked. I did not expect that. AC and fan are working.
I tightened up the connectors for that relay. That's it.
What a trip.

 

[Z71]

I world have tried a while new fuse box with all fuses and relays. It is relatively inexpensive from a junkyard and Sonics are not that hard to find.

 

[Von]

I world have tried a while new fuse box with all fuses and relays. It is relatively inexpensive from a junkyard and Sonics are not that hard to find.

Yes, inexpensive.. but not free.. like repairing the box.

I've talked to 3 other people locally who had the same problem with their small Chevys. Seems to be a common problem. I'm wondering how many of these things are in the scrap yard because of this.. overheated, toasted the engine.

 

[Rockabetty78]

It was a bad resistor. The ceramic clay coating was all but gone. Ordered one on Amazon and easily replaced it. Fan turns on and of as it should, no more issues. Problem solved.

 

[JTee2017]

It was a bad resistor. The ceramic clay coating was all but gone. Ordered one on Amazon and easily replaced it. Fan turns on and of as it should, no more issues. Problem solved.

Wow. . Thanks!

Can you show a picture or details of where the resistor is located? Also, part number?