CR-V A/C fan runs intermittently, all the time

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dlb
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CR-V A/C fan runs intermittently, all the time

Post by dlb » Wed Oct 09, 2019 11:37 am

I've done some online searches and am will be doing some testing for this problem in the next few days but as always when I'm unsure about a car problem, I like to run it by you folks here.

My '05 CR-V has two fans, one for the radiator and one for the A/C system. The one for the A/C system cycles on and off for about 5-10 seconds at a time, and at all temperature ranges. Even when I first start the car up and it's stone cold, after idling for a few seconds the A/C fan will come on for 5-10 seconds, turn off for 5-10 seconds, and on and on.

Like I said, I'll do some testing soon but I wanted to see what people here are leaning towards. I want to say it's the ECT switch but if that were the case, wouldn't it turn both fans on? I wonder if there are separate switches for the two cooling fans. Hmmm.

Thanks all.

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Re: CR-V A/C fan runs intermittently, all the time

Post by keith » Wed Oct 09, 2019 12:11 pm

There are either two or three relays in the under hood fuse fan and it is commanded on when ever the AC is on. It has nothing to do with the ECT and if the AC switch is on, that fan should run even with the engine dead cold.

The other one (or two) are controlled by the ECT, one is for when the ECT goes too hot while the engine is running and the other, if there is another, turns the fan on if the ECT goes too high after the engine is shut down and it is on a timer so if it comes on after shutdown, it runs for a specified amount of time. BTW the three relays are identical so they can be swapped for troubleshooting purposes but should not be swapped as a repair, only to confirm a bad relay.

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Re: CR-V A/C fan runs intermittently, all the time

Post by splatterdog » Thu Oct 10, 2019 5:20 am

Is the heater set to defrost when this occurs?

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dlb
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Re: CR-V A/C fan runs intermittently, all the time

Post by dlb » Thu Oct 10, 2019 1:58 pm

splatterdog wrote:
Thu Oct 10, 2019 5:20 am
Is the heater set to defrost when this occurs?
I had to check, and yes it is -- it only seems to happen when the heater is set to defrost the windshield. When I set it to anything else, the A/C fan didn't come on. Is this normal function SD, or a common problem you see with CR-V's?

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Re: CR-V A/C fan runs intermittently, all the time

Post by splatterdog » Thu Oct 10, 2019 4:08 pm

A/C on during defrost has been around for a long time. It's for moisture removal. I don't know how many times I've heard- I don't use my a/c in winter..

The cycle time may indicate a low charge but if it cooled fine this summer it should be OK. Most cars only hold a pound or so.

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Re: CR-V A/C fan runs intermittently, all the time

Post by dlb » Sun Oct 13, 2019 11:55 am

Ahhhh, gotcha. Thank you. This makes me wonder if I have some other A/C issue going on, because the A/C button does not automatically light up when I set the heater to defrost (like I've seen in other vehicles), but even with the A/C off, it has always blown really cold air -- maybe it's stuck on? I'll have to do some more digging.

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Re: CR-V A/C fan runs intermittently, all the time

Post by keith » Sun Oct 13, 2019 12:49 pm

The AC button only lights up when it is pushed in, it does not light up just because the compressor is on. Kudus to splatterdog about the defrost, I didn't think about that. In cold weather, the freon will contract a little and the pressure will be a little lower. A recharge may fix the issue but be very careful, you do not want to overfill the system. If you don't have a three gauge system, best to leave it to the pros. If you do, go for it.

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Re: CR-V A/C fan runs intermittently, all the time

Post by dlb » Sun Oct 13, 2019 5:27 pm

keith wrote:
Sun Oct 13, 2019 12:49 pm
The AC button only lights up when it is pushed in, it does not light up just because the compressor is on.
This is not always true. I have been in newer cars (like my mom's Rav4) where the light came on automatically when I adjusted the heat controls. I'm not sure if that's how my CR-V is supposed to work but I'll check it out.

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Re: CR-V A/C fan runs intermittently, all the time

Post by keith » Tue Oct 15, 2019 11:37 am

dlb wrote:
Sun Oct 13, 2019 5:27 pm
keith wrote:
Sun Oct 13, 2019 12:49 pm
The AC button only lights up when it is pushed in, it does not light up just because the compressor is on.
This is not always true. I have been in newer cars (like my mom's Rav4) where the light came on automatically when I adjusted the heat controls. I'm not sure if that's how my CR-V is supposed to work but I'll check it out.
I have not seen this. Was the light separate from the switch? Most of the time, actually in all cases I've seen in vehicle AC systems, the light is part of the switch and gets power when ever it is pushed in (turned on) and there is power from the fan switch. But my espresso machine does have a light in the switch that comes on when the water is up to temp so I suppose it could be done with the AC as well.

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