Replaced Thermostat: Cooling fan won't turn on

[Google]

Seems like there are more than one threads going on resulting from a thermostat change.

Mine is a bit different and I suspect it may have been a problem for a while now, but just now surfaced.

I had a referral for a mechanic to replace the thermostat on my Mazda3, 2005 2.0 Litre because the CEL went on and it threw the code P0126. The thermostat was indeed flaky and spent more time open then closed.

Upon checking the operating temps with an OBD scanner, coolant temps often would rise up to 200+F (93.3 C) but rarely when idling in traffic; however, most of the time it would be around 167F (75C). The replacement of the thermostat fixed that and now the engine is around 195 F (90 C). At idle it went up to 217F (103C) , but it's still within the "normal" range in the console (dash). With highway driving the air is cooling the engine but once again, no fan turns on. Temps do drop to around 195 (90C) but shoot up when idling or at a stop.


The person who did the thermostat replacement said the coolant fan should've kicked in after the car warmed up. He checked the connections, everything seemed as they should, same as the fusebox. I don't ever recall the fan ever turning on. I do hear the compressor turn on though, but not the fan. For example, after a long drive in the summer, I never heard the engine fan on after parking it. I also read somewhere that the coolant fan won't turn on until 220 F (144 C) but my mechanic says it should've come on around before 195F (90C).


Is there a troubleshooting procedure one can go through to determine what is the cause: The coolant fan wiring? Faulty coolant sensor, etc?

[m_bisson]

If it was the summer time, I'd tell you to sit in rush hour traffic with the a/c cranked. Purposely heat the engine to see if it'll trigger the fan.

What temp does it "shoot up" to when you come to a stop?

I'd leave it alone til the summer lol. The cold air outside plus you heating the air in your car could be enough to keep the engine cool.

Also, ignore the gauge on the dash. It's only 3 levels: cold, normal, too hot.

[miako]

For my car, my fan won't turn on at 195F for sure. More like 215F+then it'll turn on.

[XTOTHEL]

What's the longest you had it idle? Might need to leave it idling or a long time, or when you come back from a long trip, idle for a long time and see if the fan comes on. Don't need the hood up or anything, just listen for it.

[McGuyver_3]

your temp gauge, does it ever go over half? If not then I wouldn't be concerned. With this cold weather the fans most likely wont kick in.

[Google]

Temp gauge pretty much stays within the normal range once warmed up. It shoots up after maybe 7 minutes of idling (after long driving) on idle to over 200F or 93C.

Ok, thanks for the reassurance. I'll leave it be until summer. I have an OBD scanner on my smartphone monitoring temps. I read online who people all of sudden have steam coming from within the engine compartment. They make no mention whether or not they noticed any change with their dash temp setting.

[McGuyver_3]

when it "shoots up" does it go back down when continuing to idle or does it continue to go up?
What does "shoot up" mean? You and I could have different meanings on "shoot up"
From what you are saying you may have an issue

[Google]

Temps continue to rise during idle. I just turn the ignition off now that I have the OBD scanner connected.
What I mean shoot up it rises and keeps on rising. The only time it doesn't when driving (where it does go up and down). Before the thermostat replacement it always ran cold but I never started monitoring the temps until recently and it did go as high as over 200F just sitting in traffic for a few minutes with the old thermostat. Like I mentioned before, I can't recall ever hearing the fan go on....never.

It would be nice if we had the specs when the fan is suppose to turn on. It's like this is some sort of a secret.

[XTOTHEL]

I don't think the coolant will boil until around ~130 C. Maybe the 93 C isn't enough for the fan to kick in?

[McGuyver_3]

Temps continue to rise during idle. I just turn the ignition off now that I have the OBD scanner connected.
What I mean shoot up it rises and keeps on rising. The only time it doesn't when driving (where it does go up and down). Before the thermostat replacement it always ran cold but I never started monitoring the temps until recently and it did go as high as over 200F just sitting in traffic for a few minutes with the old thermostat. Like I mentioned before, I can't recall ever hearing the fan go on....never.

It would be nice if we had the specs when the fan is suppose to turn on. It's like this is some sort of a secret.

considering that they keep rising then you do have an issue. The temp gauge should not go over half. I found the following in alldatadiy.com
Cooling Fan Control System Inspection

1.Verify that the battery voltage is more than 12.4 V .
•If the battery voltage is less than 12.4 V , charge the battery or connect the external power supply.
2.Connect the M-MDS and access ECT PID.
3.Turn A/C switch to off.
4.Verify ECT PID is less than 98 °C {209 °F} .
•If ECT PID more than 98 °C {209 °F} , inspect ECT sensor and related wiring harnesses.
5.Verify that the cooling fan does not operate with ECT PID is less than 98 °C {209 °F} while the ignition switch is ON.
•If the cooling fan operates, inspect for following parts and related wiring harnesses:
•ECT sensor
•A/C switch
•A/C refrigerant pressure switch (High/low pressure)
•A/C refrigerant pressure switch (Medium pressure)
•VSS
•A/C magnetic clutch
•Fan control signal circuit (between fan control module terminal B and PCM terminal 1AE)
•If the all items are normal, replace fan control module.
6.Verify the cooling fan operates while the A/C switch to ON with the ignition switch at ON position.
•If the cooling fan does not operate, inspect for following:
•A/C switch
•A/C refrigerant pressure switch (High/low pressure)
•Fan control module power supply circuit
•Fan control module GND circuit
•Fan control signal circuit (between fan control module terminal B and PCM terminal 1 AE)
•If the all items are normal, replace fan control module
7.7.Verify that the cooling fan operates with following table.
•If the cooling fan operation is not specified, inspect for following:
•A/C refrigerant pressure switch (Medium pressure)
•If the A/C refrigerant pressure switch (Medium pressure) is normal, replace fan control module.
8.Turn A/C switch to off.
9.Start the engine and idle it.
10.Verify that the cooling fan operating speed increases relative to ECT PID increases.
•If the cooling fan speed does not increase inspect following:
•ECT sensor (characteristic) (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION[LF, L3].)
•Fan control signal circuit (between fan control module terminal B and PCM terminal 1AE)
•If the all items are normal, replace fan control module

[Google]

Thanks McGuyver.

The temperature gauge does NOT go over half. Temps keep rising only when idle and stabilize when driving on the highway to around 90C. How reliable is the reading on the dash?

I did find some additional info on when the thermostat goes fully open:



full–opening temperature
(°C {°F})

97 {207}


So the magic number then is 209F or 98C where the cooling fan "should" kick in"?

I think I might have to go to the dealer to get these tests properly diagnosed.

If the cooling fan needs to be replaced, does the front bumper have to come off to gain access to the assembly?

[McGuyver_3]

so wait, now you are confusing me. You state at idle the temperatures go up. What I was asking was does the temp gauge on your dash go up? They are not supposed to move. That the water temp rises is normal as you are no longer moving. Its similar to oil temperatures. at driving speeds it will stay low, when you get to a standstill or heavy stop/go it will rise and hold around 100C.
Not sure if the front end would have to be removed or not. My "guess" no, but manufacturers do like to hide screws and bolts everywhere so it is a possibility

[Google]

Sorry for the confusion McGuyver. :(

The temp gauge on dash not on smartphone has never gone up past center even at 217F (103C) as per OBD. The dash temp gauge (does move normally) from cold to medium. The OBD temps do shoot up but have been below 202F today.

I was wondering about the removal of the cooling fan since I was told because of the very tight crawl space, it would be best to remove the front bumper to get access to the coolant fan should it need replacing.

I guess, if anything, I might guess that it might be the coolant fan module? I guess when temps get warmer then I'll be able to better gauge if the cooling fan turns on or off?

[McGuyver_3]

Sorry for the confusion McGuyver. :(

The temp gauge on dash not on smartphone has never gone up past center even at 217F (103C) as per OBD. The dash temp gauge (does move normally) from cold to medium. The OBD temps do shoot up but have been below 202F today.

I was wondering about the removal of the cooling fan since I was told because of the very tight crawl space, it would be best to remove the front bumper to get access to the coolant fan should it need replacing.

I guess, if anything, I might guess that it might be the coolant fan module? I guess when temps get warmer then I'll be able to better gauge if the cooling fan turns on or off?

If your temp gauge on the dash does not move then I wouldn't be concerned at this time. See how things pan out over time. It you notice anything a miss then be worried about it. You may not hear the fan as it most Likely will not run at full speed. It only runs as fast as it needs. Just keep an eye on it

[m_bisson]

Like I posted, the gauge on the dash is an idiot gauge. It's cold, normal, or too hot.

Leave things alone unless the gauge goes into the "too hog" range. It likely won't be a gradual movement, it'll move up there fairly quickly.

[Google]

Thanks guys. When I turned on the defrost, the A/C kicked in. I opened up the hood. The cooling fan was on.
I'll leave things be.

[Flagrum_3]

Thanks guys. When I turned on the defrost, the A/C kicked in. I opened up the hood. The cooling fan was on.
I'll leave things be.

So the fan works with A/C on, but what about without A/C on? and I'd check for 'AIR' in your coolant system. You could have an air bubble, introduced when you replaced the thermostat.


_3

[Google]

So the fan works with A/C on, but what about without A/C on? and I'd check for 'AIR' in your coolant system. You could have an air bubble, introduced when you replaced the thermostat._3
I haven't seen or heard the fan turn on with the A/C off (with the exception of the defrost).
Back in the day, I would squeeze the radiator hose after replacing the thermostat. Don't modern cars now have a bleeder to remove the air?

[Google]

I determined the other day the fan kicks in only when the engine temp reaches 217 F. Is that too high? Dealer says don't worry about it.

[McGuyver_3]

217F=103C
I wouldn't worry about it

[Flagrum_3]

217F=103C
I wouldn't worry about it

+1. Think I read in the manual it's set at 217F. Why? who knows, it's got a 190F thermostat on there....go figure.

[TheMAN]

these motors run hot due to emissions reasons

[Flagrum_3]

these motors run hot due to emissions reasons

And your point?

[m_bisson]

And your point?

What's your problem? His post was relevant!

[Flagrum_3]

What's your problem? His post was relevant!

I'm just asking him to explain his point!...yu mad?


_3

[XTOTHEL]

FYI my 2.0 2010 runs to a max of 93 C after driving on the 401