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My problem was that there was no fan on when I got the warning "a/c off due to high temp." After the motor "cooled down", the radiator fan was on low when the a/c was on. At this point, I don't believe my medium or high speed is working. I will try to do some troubleshooting this week if I have time. Car has not been used since I got home after the A/C off due to high temp message.
 

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If high speed is out, it's due to a bad relay. High speed is putting full battery voltage on the fan. The lower speeds are created by placing resistors in series. But the resistors tend to burn out.
 

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I will be testing the fan motor and all the relays this week. I should have an update this weekend on my results. Since it is the 1.8L motor, there is easy access to the wiring harness to the fan and the relays are right there next the battery. Plan on using my battery jump starter to power/test the fan motor and relays. I will update this weekend.
 

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I'm experiencing a similar issue with my Cruze. It's a 2013 1.4L with ~90K miles, getting no heat from the air vents when the temperature gauge is reading normal (just a tick to the left of being straight down), then I got heat for about a minute, and the gauge jumped straight to the peg. (Killed the engine immediately and added coolant before driving any farther; I'm really hoping there isn't any long-term damage to the engine...)
I know for a fact that I have a coolant leak, just surfaced yesterday, but I wanted some direction on the temperature jumping. I haven't had a chance to troubleshoot the fan, but I do know it's running at least on some temperatures.
After I address the leak, should I be concerned about replacing sensors or thermostats?
 

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You have to address the leak first. I would hold on replacing anything until then. Having gone through this entire scenario, without drinking the Kool Aide, first on my change list after the leak is resolved is the serpentine belt if it is original.
 

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I would not worry about replacing any temps or sensors. You realize you have a leak somewhere, repair the leak and fill the system with coolant. Remember to open the bleed screw near the top of the radiator when filling with coolant to get as much air out of the system as possible. Be patient when filling, as soon as you see coolant coming out of the bleeder screw tighten it up and fill the reservoir then put the cap on the reservoir. Now it's time start the engine with the heat on full blast. Fill the reservoir as needed until filled. You may have to drive it a few times to get all the air out of the system. Hopefully you will get heat shortly after you start the engine. Good luck.
 

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The fan in the Cruze is infamous for going from "low-medium-high" to "off-off-high". In your case, it might have gone to "low-off-high". The medium speed may have burned out. That would explain why you saw it running later (on low).

If I'm correct, the fix is to replace the fan as the burned out part (the resistor pack) is only sold as part of a complete unit.
Do you by any chance have the schematic for this resistor pack / switch setup? Here is a generic one for what it's worth though.

Text Diagram Line Font Design

Someone mentioned the numbers are low. So. If you get no reading. That resistor is blown.

I could be wrong though.
That is correct. I posted that in another thread similar to this one. Essentially if you have infinite resistance, or some meters may say xx G ohms or 99 etc you have an open which means bad resistor.

As I have not taken direct reading readings of the actual resistors yet (I may try and do that later today), they will obviously have a lower ohmic reading.

I found a post by Frankh that appears to be an easy way to test the fan/resistor. I should be able to get the cover off the fan motor terminals and just use a jumper from the battery positive terminal to each of the fan speed terminals. I assume it will identify which fan speed is not working due to a bad resistor. If the fan runs at each terminal, I will then test the relays. Looks like it should be quick and easy. Below is what I found from an April 2018 post.


frankh

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Sadly the function of relay 10 is the same no matter which way round its installed.. I just checked and the circuits are cross connected.

However I did get access to the fan motor terminals. you could take a jumper wire from the battery positive and go direct to the three terminals shown. The right terminal with a scorch mark is a ground.. ask me how I found that out..:)

The little cover pops off if you insert the screwdriver as shown.. There is a little dab of glue that seems unecessary to hold it down as well.

If the fan don't run with direct jumpering i'd say you're into a new fan.

Oh I did get the big connector halfway off with levering and swearing.. but it was starting to break.. its almost like its glued on. Clearly though its just the plastic lever at the top of the pics is pressed down (towards you) and then pushing the connector downwards.. Mostly by using a screwdriver in the place shown and on the other side.​
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Last edited by frankh; 04-02-2018 at 06:15 PM.​
Can you post the link for this?

If high speed is out, it's due to a bad relay. High speed is putting full battery voltage on the fan. The lower speeds are created by placing resistors in series. But the resistors tend to burn out.
So no more fusible links for high speed?
 

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Had a chance to check the radiator fan, 5 fan relays, and 3 fuses. All checked out good. Fan when powered directly had all three speeds. All relays checked out when power applied. Though the fuses looked good, checked them with my meter and they were all good.

Would a bad temperature sensor or thermostat cause me to get the "a/c off due to high engine temp" and not cause the fan to run? I did not have any codes (and no codes pending). I have not driven the car since I had the A/c off message, but maybe I just need to drive it and see what happens? Any suggestions of what to check next?
 

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Do you by any chance have the schematic for this resistor pack / switch setup?
Nothing handy in digital form. The setup has 5 relays. It converts the ECM's "binary word" output to a "one of 3" selection that feeds the resistors & bypass.
 

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Had a chance to check the radiator fan, 5 fan relays, and 3 fuses. All checked out good. Fan when powered directly had all three speeds. All relays checked out when power applied. Though the fuses looked good, checked them with my meter and they were all good.

Would a bad temperature sensor or thermostat cause me to get the "a/c off due to high engine temp" and not cause the fan to run? I did not have any codes (and no codes pending). I have not driven the car since I had the A/c off message, but maybe I just need to drive it and see what happens? Any suggestions of what to check next?

I might have misread what you said, but did you bypass the speed switch to get your results? If so, it is probably the speed switch. Also can you post the link for the thread you referenced above?
 

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To check the fan motor I put 12 volts directly to each terminals on fan motor to make sure the resistor was O.K. As I powered each of the terminals, I had a distinct change in speed, low, medium, and high. I pulled the cover off of the top of the connector as Frankh showed which made it easy to access the terminals.

I am not familiar with a speed switch, I did read where there was a relay which was for speed control and I checked that relay which was o.k. Where would the radiator fan switch be located? Any help or suggestions would be appreciated.
 

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I have a 2013 and got the message a couple weeks ago after taking a 4 hour trip. Well actually it flashed when I got back home with 10 minutes before I pulled in my driveway. My fluid was low. I looked and looked and finally found it leaking small drops on the bottom of my thermostat. What's strange is when I took the thermostat out it fell apart and the gasket was blown out on the bottom. My car never showed a code and due to humidity in my area I use the defroster a couple times a week. I always got heat, AC and the temp never showed hot, but my car did start sluggish and sometimes I'd have to push the start button a second or third time to start the car. Also when I shut it off my car would rumble for a few seconds. I changed the thermostat and my car starts and shuts off perfectly now. I don't know how the new thermostat made a difference but it did.
My main point is look under your thermostat for a small drop leak. It's kinda cluttered under there and hard to see
 

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Thanks for your help. My coolant is full. I replaced my thermostat about 5 weeks ago due to the heater in the thermostat shorting out and causing the radiator fan to run full blast (I also had a CEL code when I had the thermostat fail). My coolant has remained full since I replaced the thermostat. What is strange, if my car was "overheating", the radiator fan should have been roaring to cool down the motor when I checked.
 

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UPDATE: More info. Drove the vehicle today and vehicle did not overheat, but also, the fan did not turn on when I put the A/C on. Last time the fan was running when I checked with the A/C on. Like I mentioned before, the fan worked when I put power directly to it (all 3 speeds), all relays and fuses tested good, plus no CEL codes or pending codes. Besides a possible wiring issue, all what else can I check? It is frustrating because all seems good,, but I hesitate to drive long distance because something is not right.

2ND Update: I let the car cool off and then started the motor and tried the A/C, radiator fan came on low. Coolant temp was around 140 degrees. Shut off A/C and tried again, fan came on and coolant temp was around 160's. Shut off and tried a third time, nothing, a/c compressor kicked in, but radiator fan did not. Coolant temp was around 180 degrees when nothing happened. I did this all with the car idling in my garage. I then took it for a ride with the a/c on and a/c worked great, stopped and checked if radiator fan was running, and nothing. The coolant temp was around 200 degrees when I checked.

Does this help anyone to direct me where to check next? Thanks in advance for all your help.
 

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I'm thinking it may be the medium speed fan relay. Right now I'm away from my books, so I can't look up which one that is. But it is a replaceable relay in the underhood fuse box.
 

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From what I read it is relay #9. I did check that relay and it tested fine. I know it could be a wiring issue, but I have no reason to think anything happened to cause a wiring problem. Thanks for your help, it really has me stumped.
 

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From what I read it is relay #9. I did check that relay and it tested fine. I know it could be a wiring issue, but I have no reason to think anything happened to cause a wiring problem. Thanks for your help, it really has me stumped.
Did you try jumping the contacts on that relay to see if the fan runs?
 

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I did not do that. I was not quite sure how to do that. To do that, do I need to get the car to operating temperature or can I do it with the car not running, but with the ignition turned turned on? On all the relays, I put 12 volts to them and checked for continuity, all tested fine. All 3 fuses were good also, I can try jumping that relay, I would just need some guidance. Thanks again for your help.
 

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I did not do that. I was not quite sure how to do that. To do that, do I need to get the car to operating temperature or can I do it with the car not running, but with the ignition turned turned on? On all the relays, I put 12 volts to them and checked for continuity, all tested fine. All 3 fuses were good also, I can try jumping that relay, I would just need some guidance. Thanks again for your help.
 

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Just for grins, check the thermisters. They should give distinct readings at different temps. Pull the wire harness off. Measure the resistance when cold and warm up the car and measure again. If there is no change, that particular thermostat is bad.
 
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