My independent mechanic says my radiator fan and AC fan are cycling too much. The dealer says they are not. I know it started about 6 months ago and that I get 2 miles per gallon less now. If the heat, defrost selector is in any position it happens as long as the fan control in not on off.
The fans run for 5 seconds and then are off for 20 seconds. The independent says the AC has refrigerant but doesn’t know what is causing it. It happens at all outside temperatures. It happens at all car temperatures. (Just started, been driving for an hour etc.) Help it is driving me nuts.
Is your car overheating? The ECM controls the action of the cooling fans. It is programmed to work in such a manner as to keep the engine from overheating. If it is not overheating, then it is working as intended. The fans should stay on anytime the A/C is on. It will not affect gas mileage as long as the engine is not overheating. The cold temperatures across the US probably are more responsible for your poor gas mileage.
Ac on= Fan on
That was really confusing, and some things need to be clarified here. You’ve got reference to three different fans going on in there (but there are two) and I am not sure I get what you’re trying to describe.
Your radiator fan and AC system fan are the same thing, and that is the thing that cycles. It might be a dual fan system, but that will just be related to a hi and lo for the cooling/AC fan and controlled by computer and relays - i.e. it has no controls for the humans to use. This fan is mounted to the radiator, and the AC condenser is mounted to the front of that which is why the same fan does engine cooling & AC.
Then there is your blower fan that is inside of the vehicle under the dash. That just moves air through the vents and out into the cabin, whether the air is being heated or cooled or not. On vehicles with automatic climate control, that fan will also be cycled on and off (or up and down). But without automatic climate control, a human cycles it on or off with the switch on the dash.
If we are really taking about the radiator/AC fan then how do you know it does this on/off cycling and how do you know it started 6 months ago? And if it started 6 months ago, what does it mean to say “Just started, been driving for an hour etc.”
Or are you talking about the blower fan inside of the vehicle cycling on and off?
The fans that are cycling are the two fans by the radiator. One on the drivers side and the other on the passenger side. I can hear the fans when the come on and go off while I am driving. No automatic climate control. The heater fan in the cabin runs by turns the switch from off to a fan speed. The two outside fans do their cycling thing when ever the heater fan in the cabin is not in the off position. The just started refered to the condition of the car. When I start it the two outside fans start cycling. While I am driving they continue to the cycle for however long the trip is.
The AC is off. I understand AC is on when using defrost. When I am not using defrost. (Cabin air blowing in your face and on your feet) The cycling continues.
Ok, this is not normal behavior for the fans no matter what the dealer says so something is up. The two things that trigger the fans are the engine coolant temp and the A/C system. Don’t assume, btw, that the only times the compressor runs is when the switch is either on A/C or defrost. Perhaps you know for a fact, but for some reason I have a vehicle where the compressor also runs in the split face/feet position. It’s just wired that way, though I can’t say why.
The question about A/C refrigerant isn’t whether it has any, but whether or not the pressure is correct. There is a low pressure switch in the system that will shut down the compressor if the pressure goes too low. So if refrigerant levels are marginal the compressor will continually kick on and off. The PCM’s fan control is probably looking at that circuit, though I don’t know that for a fact. But someone should find out if the cooling fan on/off cycling goes with the compressor on/off cycling.
In addition, someone should verify what the coolant temperature sensor is doing as it could have a problem (or be reading some other problem) that is doing this with the fans. Proper coolant temp AND accurate reading of it is very important to MPGs, btw, though a 2 mpg drop is really nothing especially given how this winter has been going.
I seem to have a similar issue, I think. I go to pick my grandchildren up at the bus stop & am sitting there idling. I hear what seems to be the AC kicking in. This happens no matter what the temperature, even down to 20- 30 degrees. I hear the click, can almost feel the compressor kick in, and an increase in engine sound. It runs about 20- 30 seconds, stops & repeats again in about 30 seconds. Can’t figure out why the AC would be kicking in. Just to test, I sat idling on the driveway at about 35 degrees & turned the AC on. It’s the same sounds & feeling I get when idling even though the weather is cold. If I have the defroster on, it is set to the warm side so I don’t think the AC should kick in.
It’s a 2003 CR-V EX.
@TonyMan, that does just sound like the cooling fans are kicking on and off in response to coolant temperature. The temp rises as you sit at idle until X degrees (probably somewhere between 220-240F). The computer turns on the fan. Its cold out so the fan pulls the coolant temps down pretty rapidly. Off go the fans. Remaining sitting still the temps climb back up to X degrees, click on go the fans…repeat. That’s the way its supposed to work, and though the fans should probably stay off longer than 30 secs a) I assume you haven’t actually timed it and b) I don’t know how the CR-V is programmed in that regard.
Thanks cigroller, it sounds like it’s not an issue then. I was just concerned due to the weather being cold and it did sound like the AC compressor kicking in.
my dodge had flaky a/c pressure sensor. you turn on a/c, high side goes up, sensor tells computer and computer turns on fans. too much freon was added during a recharge and we believe sensor failed on and from than on, rad fans would run constantly. with ac on or off. yes we removed some freon and fans still continued to run. not sure how the honda fans are wired. we know that cooling fans run based on various inputs.ac on/off, coolant temp hi/lo and so on.
Any time a dealer says “they all do that” have them find a similar model in their shop and show you that they are speaking the truth.
Good idea. Thank you very much.
Also the car is not running hot for those who asked. The gauge shows is it running cooler then half way to hot.
U can unplug fuse/relay for cooling fan. Remember to put it back when spring comes.
@wedrivehondas, has the temp gauge always run there? Most are calibrated to run dead center of the gauge when fully warmed up. The cooling fans may be misbehaving because of a faulty thermostat. If the engine runs too cold, the computer will enrich the fuel mix to try and warm the engine, wasting gas.
And, I would not unplug the fan relay for the wintertime. I just had a sensor fail for the fan controls on my older Toyota, and even on 20° temps, the engine began overheating at long stop lights with the fans not running at all.
Are you actually using the AC? Do you turn it on then? In the winter?