Radiator fan spinning at weird times

1525 Views 13 Replies 6 Participants Last post by REN69, Nov 20, 2017

GingersHadSouls

Discussion Starter · Nov 16, 2017

Hi there,

I've recently purchased my car this summer and everything has been going fine since then. It's a 2007 Matrix Base model. It's used at 175000km.

Now the part that's confusing me is the radiator fan spinning when there is visibly no need to. I've never had any heat problem, even during really hot days (45C) in stop/go traffic. Now, winter time is coming sooner than later. We've been hit by -5C recently and started using the heat in the car to get comfy. If the car is started and no accessories, lights, heating, fans, nothing is on, the rad fan will never turn on until it reach 25-50% of my collant temp indicator. I've never had it past 60% even when pushing the car really hard on hot days. But if I put the heat on (dash/foot, 1/4 speed, dialed to max hot) on startup, the fan will spin every 30 seconds for 2 sec (approximate, never really counted) even though my temp gauge still haven't moved from the coldest.

Is this a safety/maintenance feature ? Is it a bad electrical wiring from a previous fan/radiator change ? (The previous did nothing but he was not the original owner)

I'm still discovering things the previous owner did but I'm a student and needed the car so I can't really complain for the price I got it. It seems in decent shape all around.

Thank you for your input !

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TrdSpeed140

· #2 · Nov 16, 2017

when you say that you set the heat on (dash/foot, 1/4 speed, etc etc), what do you mean dash/foot? do you mean the upper left setting (feet/register vents), or do you mean the upper right setting (feet/defogger vents)?

the upper right setting incorporates the defogger/defroster which runs the A/C compressor. the A/C compressor working would turn on the fans so that the A/C condenser gets airflow (A/C condenser is the heat exchanger right in front of the Coolant radiator).

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GingersHadSouls

Discussion Starter · #3 · Nov 16, 2017

Upper right setting, feet and windshield and side windows vents.

I see, even though the AC is set to OFF and the air is not set to RECIRCULATE ?

The AC would start so the evaporator could dehumidify the air and thus, decrease the cabin humidity over time ? The car is wired like that by default ?

Next time I use the car in sub zero temp (Today it's 5C) I could try to see if I press the AC button, if the fan would spin more.

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TrdSpeed140

· #4 · Nov 16, 2017

GingersHadSouls said:
Upper right setting, feet and windshield and side windows vents.

I see, even though the AC is set to OFF and the air is not set to RECIRCULATE ?

Yes

The AC would start so the evaporator could dehumidify the air and thus, decrease the cabin humidity over time ? The car is wired like that by default ?

Yea, pretty much

Next time I use the car in sub zero temp (Today it's 5C) I could try to see if I press the AC button, if the fan would spin more.

In the winter, I would always disconnect the electrical connector on the A/C compressor. doing this would keep the fan from turning on when you have the defroster setting ON. this also should not cause any sort of check engine light, at least it didn't for me. I did this because when the A/C would kick on, it would diminish the amount of HOT air coming out of the vents because it would start mixing with the cold air blowing through the A/C evaporator.

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GingersHadSouls

Discussion Starter · #5 · Nov 16, 2017

I see. Thank you very much for your fast answers and insight !

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invader

· #6 · Nov 17, 2017

AC is activated at slightly clockwise of floor vent setting... I've modified the cam behind vent control knob to have AC activated only at slightly clockwise of floor/windshield vent setting.

AC does not go on at all when ambient temperature is at 0C (32F) or colder.

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GingersHadSouls

Discussion Starter · #7 · Nov 17, 2017

invader said:
AC is activated at slightly clockwise of floor vent setting... I've modified the cam behind vent control knob to have AC activated only at slightly clockwise of floor/windshield vent setting.

AC does not go on at all when ambient temperature is at 0C (32F) or colder.

Are you sure about this ?

Cause here in Canada, there was a definite -5C, -10C during the night that was felt recently, but the car, after a 1h30 car ride or cold started, both spun the radiator fan during cabin heating ventilation, only tested on windshield setting, will try some other day with only Dash/face ventilation.

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invader

· #8 · Nov 17, 2017 (Edited)

GingersHadSouls said:
Are you sure about this ?

Cause here in Canada, there was a definite -5C, -10C during the night that was felt recently, but the car, after a 1h30 car ride or cold started, both spun the radiator fan during cabin heating ventilation, only tested on windshield setting, will try some other day with only Dash/face ventilation.

0C (32F) ambient (no windchill factor) or colder. That's what the experts say, and they all swear by it... I'm in Northern Ontario and it's now -14C.

AC will be activated at slightly clockwise of floor vent setting up to windshield vent setting ONLY! You can feel the extra resistance as the switch is being compressed.

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GingersHadSouls

Discussion Starter · #9 · Nov 17, 2017

invader said:
GingersHadSouls said:

Are you sure about this ?

Cause here in Canada, there was a definite -5C, -10C during the night that was felt recently, but the car, after a 1h30 car ride or cold started, both spun the radiator fan during cabin heating ventilation, only tested on windshield setting, will try some other day with only Dash/face ventilation.

Click to expand...

0C (32F) ambient (no windchill factor) or colder. That's what the experts say, and they all swear by it... I'm in Northern Ontario and it's now -14C.

AC will be activated at slightly clockwise of floor/windshield and up to windshield vent setting ONLY! You can feel the extra resistance as the switch is being compressed.

Gotcha, and if it's at windshield and it's -10C outside. Will the compressor, and thus the radiator/condenser's fan start up?

By my experiment it will, right ? or is there a wiring problem?

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circuitsmith

· #10 · Nov 17, 2017 (Edited)

AC does not go on at all when ambient temperature is at 0C (32F) or colder.

GingersHadSouls said:
Are you sure about this ?

Has to be. Otherwise the evaporator would ice up.

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Supersonic

· #11 · Nov 20, 2017

Noticing a similar issue, my fan comes on even before the motor is up to operational temperature. I almost never use defrost, so it seems I have some more diagnosing to do. It doesn't stay on for long, so it is cutting off on it's own.

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GingersHadSouls

Discussion Starter · #12 · Nov 20, 2017

So today I've started up my Matrix, at -5C outdoor while I was clearing it of any snow, and then got caught up in shoveling the driveway so the car ran for 5 minutes and was getting to operational temperature, about 33% there and I carefully check everything inside on startup and set everything to off. The radiator fan didn't spin until later, when it hit operation temp while idling (I know, it's not optimal to wait that long while idling). At that point, I put the ventilation to max, full hot and only on the windshield defrost (also activated rear window defrost if the information is needed) and it didn't took long for the radiator fan to spin stop and go. So in my case it may be the compressor starting as the engine bay could have heated the heat sensor. Will need to try in a -20c temp to see if there is really a temp cut-off for the compressor.

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TrdSpeed140

· #13 · Nov 20, 2017

I wonder if the A/C pressure switch is coming into play. as the A/C runs in defrost mode, the condenser heats up. in a stationary car there might not be enough airflow, and thereby heat exchange, even in very cold weather, to adequately lower the refrigerant pressure.

just my thoughts, I could be wrong.

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REN69

· #14 · Nov 20, 2017

Sounds like an AC issue... probably the AC compressor going on and off.

if you have the system set to go to defrost, the AC will go on as well to defrost quicker... if it's going on and off, could be a problem with the AC system and not the heater.

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