O'er heatin' problem
#1
09-08-2018, 05:48 PM
O'er heatin' problem
Complete re-edit...
I have an '11 Crown Vic (270k miles) with an overheating problem that I believe is being caused by the rad fan not turning. Here's what I've seen so far...
1 - The overheat condition doesn't happen while moving, it only happens while in park after idling for a while
2 - Top radiator hose DOES get hot
3 - If the a/c is off, the rad fan DOES NOT turn at all during overheating as the temp gauge moves all the way up
4 - At normal engine temp the rad fan DOES turn as soon as the a/c is turned on, but I've only observed this so far at normal temperatures.
5 - During the times it overheats and the a/c is on, the cabin vent air gets hot and humid right when the overheating occurs. I haven't yet made it a point to check the rad fan at this point to see if it's still turning.
6 - During testing, after getting the engine temp up to idle hot and the temp gauge read normal in the middle, to trigger it to overheat I had to run the engine at 2k rpm for over 5 mins before the dash temp gauge began to rise. After the gauge begins to creep up I've let off the gas but the temp continues to go all the way up. Although to trigger the overheat condition I ran it at 2k for a while, it DOES overheat by simply sitting in park and idling.
7 - The coolant reservoir cap has a small leak but I don't think this is a major factor. I've continued to top off the reservoir throughout my testing and overall there doesn't seem to be much coolant leaking from the reservoir. Although, you CAN hear air seep from the reservoir cap when you squeeze the top rad hose.
The main problem seems to be the rad fan not turning. Any ideas? I'm all ears.
I have an '11 Crown Vic (270k miles) with an overheating problem that I believe is being caused by the rad fan not turning. Here's what I've seen so far...
1 - The overheat condition doesn't happen while moving, it only happens while in park after idling for a while
2 - Top radiator hose DOES get hot
3 - If the a/c is off, the rad fan DOES NOT turn at all during overheating as the temp gauge moves all the way up
4 - At normal engine temp the rad fan DOES turn as soon as the a/c is turned on, but I've only observed this so far at normal temperatures.
5 - During the times it overheats and the a/c is on, the cabin vent air gets hot and humid right when the overheating occurs. I haven't yet made it a point to check the rad fan at this point to see if it's still turning.
6 - During testing, after getting the engine temp up to idle hot and the temp gauge read normal in the middle, to trigger it to overheat I had to run the engine at 2k rpm for over 5 mins before the dash temp gauge began to rise. After the gauge begins to creep up I've let off the gas but the temp continues to go all the way up. Although to trigger the overheat condition I ran it at 2k for a while, it DOES overheat by simply sitting in park and idling.
7 - The coolant reservoir cap has a small leak but I don't think this is a major factor. I've continued to top off the reservoir throughout my testing and overall there doesn't seem to be much coolant leaking from the reservoir. Although, you CAN hear air seep from the reservoir cap when you squeeze the top rad hose.
The main problem seems to be the rad fan not turning. Any ideas? I'm all ears.
Last edited by bradleyheathhays; 09-09-2018 at 04:48 AM.
#3
09-09-2018, 04:19 AM
You might want to confirm the cooling fan(s) come on when the temp gets hi enough. Do you see/hear them come on at any time ? Should come on when A/C is selected.
With those miles your suspects of the thermostat and water pump are right in there.
With those miles your suspects of the thermostat and water pump are right in there.
#4
09-09-2018, 05:05 AM
The rad fan does come on when the a/c is turned on. But when I left the a/c off and triggered it to overheat by running it at 2k for a while the rad fan never came on. I'll keep testing but it seems like the rad fan doesn't come on at all unless the a/c is on.
Since the rad fan obviously works, what should I be testing to see what's not triggering the fan to come on when the gauge is reading hot? Is there some kind of temp sensor switch that's malfunctioning?
Since the rad fan obviously works, what should I be testing to see what's not triggering the fan to come on when the gauge is reading hot? Is there some kind of temp sensor switch that's malfunctioning?
#5
09-09-2018, 07:51 AM
Your vehicle should have cylinder head temp (CHT) sensors located on the rear of each head if I recall correctly..
The PCM uses those signals to control the cooling fan(s).
Did the check engine light come on at any time? If so, there should be a code in the PCM that should help provide some direction.
Some engines had both , coolant switch and CHT.
Unless you want to replace a lot of good parts , it would be better if you had someone with a good scan tool verify just which part is malfunctioning., especially if it is the PCM.
The PCM uses those signals to control the cooling fan(s).
Did the check engine light come on at any time? If so, there should be a code in the PCM that should help provide some direction.
Some engines had both , coolant switch and CHT.
Unless you want to replace a lot of good parts , it would be better if you had someone with a good scan tool verify just which part is malfunctioning., especially if it is the PCM.
#6
09-09-2018, 10:26 AM
Your M/Y has a CHT only, it’s mounted foward on left/drivers head..
If hot enough it should be going into limp mode, and the fail safe should trigger the fan-A/C to help control the over temp condition as well as set a CEL/DTC.
If you drive the car with the A/C on continuous do the temps remain normal? If so, should help to prove out hardware as cause. Checking U/L coolant hoses with a temp gun can help diagnose circulation issues. By hand, less accurate but can detect a flow loss/restriction.
You could check the CHT connector/pins,, as well as do a voltage return check to see what temp range it’s reporting to the PCM.
PCM controls fan run through the fan module. Being the fan runs in A/C, module should be good.
If hot enough it should be going into limp mode, and the fail safe should trigger the fan-A/C to help control the over temp condition as well as set a CEL/DTC.
If you drive the car with the A/C on continuous do the temps remain normal? If so, should help to prove out hardware as cause. Checking U/L coolant hoses with a temp gun can help diagnose circulation issues. By hand, less accurate but can detect a flow loss/restriction.
You could check the CHT connector/pins,, as well as do a voltage return check to see what temp range it’s reporting to the PCM.
PCM controls fan run through the fan module. Being the fan runs in A/C, module should be good.
#7
09-09-2018, 11:24 AM
No I don't believe my check engine light has come on.
Unfortunately when I hook my scan tool up it only says "ERROR.' This vehicle was originally a police car and then a cab and it has a ton of extra wires running through the dash where different equipment was hooked into it's electrical system. The equipment has all been removed but the wires were left in place. I think this may be causing my ERROR messages.
Hayapower...the car DOES overheat when the a/c is on. Something to note is that when it overheats when the a/c is on, the vent air becomes hot and humid right when the overheating begins.
I'll be replacing reservoir cap, thermostat and flushing the system both directions (w/o thermostat installed) just to rule out some simpler problems. But because my fan isn't coming on at this point I could use advice on how to test the parts that are responsible for turning the fan on. I have a multi-meter but need specific advice on how to set it and what what to test.
Unfortunately when I hook my scan tool up it only says "ERROR.' This vehicle was originally a police car and then a cab and it has a ton of extra wires running through the dash where different equipment was hooked into it's electrical system. The equipment has all been removed but the wires were left in place. I think this may be causing my ERROR messages.
Hayapower...the car DOES overheat when the a/c is on. Something to note is that when it overheats when the a/c is on, the vent air becomes hot and humid right when the overheating begins.
I'll be replacing reservoir cap, thermostat and flushing the system both directions (w/o thermostat installed) just to rule out some simpler problems. But because my fan isn't coming on at this point I could use advice on how to test the parts that are responsible for turning the fan on. I have a multi-meter but need specific advice on how to set it and what what to test.
#8
09-10-2018, 01:05 AM
Tested water pump and it's working good. Now, I've replaced both the reservoir cap and thermostat with new.
Then did some more testing by way of observing the fan speed when turning the a/c on and off. Fan speed seemed sluggish as if it wasn't being properly commanded. At different points it seemed like it wanted to turn but would stop. Maybe a dumb idea but after turning the a/c off and the blades came to a stop I took a small twig and gave the blade a quick push and it slowly started going again.
So what is this a bad fan motor maybe? And if so, where do you get just the motor? Can't find it at any of the major car store sites.
I've also read the connectors on either end of the fan control module (connected to the fan body) can get corroded.
#9
09-10-2018, 10:53 AM
Cooling fan is variable speed..
With the A/C set to Max, blower selector set to HI, the cooling fan should run full speed.
With the ignition Off, check the cooling fan for free unrestricted rotation.
Next,, ignition Off, unplug the CF ‘module connector’ and check for battery voltage present on pin 1 and Pin 2 as the ground. Yes/No?
Next,, ignition Off, test run the cooling fan. Unplug the CF motor connector and using test leads (best to circuit protect to 30 amp) add battery voltage on the Red wire, grounding the Black. Motor should run full speed. Yes/No?
Next,, Plug the CF ‘module connector’ back in to the module, CF ‘motor connector’disconnected,, test the voltage on the Pin for the Red wire out of the CF motor connector on the module side .
Is the voltage 10,, or greater than 10v?
Id look at getting the DLC active as well, if not for this concern but anything else that comes up. By Error, if it means no communication, check the fuse for the cig lighter etc. it powers the DLC.. (fuse 16-20amp in the CJB).
Harness side
Last edited by Hayapower; 09-10-2018 at 10:55 AM.
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