babyhuey sir,

I bought a 2000 ES for my daughter. I have been getting all the periodic maintenance squared away before she goes off to college next month.

The one thing that is puzzling me is the way the cooling fans are operating. When I push the A/C button, both the radiator fan and the A/C condenser fan immediately come to life and run together even when the engine is cold in the morning, I can understand why the A/C condenser fan would run, but why does the radiator fan run along with it even though the engine is still cold? Is this normal? Especially since this engine takes three times longer to warm up to operating temperature than any of my other cars. Is this normal?

Anyway, before long and at normal operating temperature, both fans start cycling on and off together about every twenty seconds... I suppose when the A/C compressor clutch engages and disengages. The “radiator fan” never runs by itself. I have never seen these two fans run separately. Why have two separate [big noisy roaring] fans and then design it so they always run in unison? It would be more sensible if the A/C condenser fan would run continuously anytime the A/C is selected; and the radiator fan was controlled by coolant temperature and would run when needed. This is how all my other cars electric fans seem to work.

The 4 cylinder 1.8 liter engine runs very smoothly in "Drive" at about 700 RPM. But when the A/C clutch engages and the two fans come roaring on, everything vibrates excessively even making the hood shake. This is very annoying.

Is this how the fan operation is suppose to be? Would you say this annoying vibration and hood-shake is normal?

Since I have never seen either fan run independently from the other, would it be OK to just unplug one of them in order to cut the fan noise in half and still have adequate cooling. The coolant coils and condenser coils are sandwiched together like a normal radiator, aren’t they? It’s not like the coolant coils are only on the driver’s side in front of a dedicated “radiator fan” and the condenser coils are only on the passenger side in front of a dedicated “condenser fan” is it?

It also seems goofy to have two fans, and then design things so they both turn completely off like that and not have any airflow over the radiator at all for a while. Especially considering it’s 95-100 degrees here and the system is still telling them to stop for a while. You would think it would be better to simply have lower fan RPM and nice consistent [quiet] moderate airflow rather than this on-off-on-off roar constantly. Is there a way to step them both down to a lower quieter RPM or something? Do you have any other suggestions? It just seems like it could be alot better.

Could you take a minute to comment on all this?

Thank you for always being so patient with everyone like me and their lame questions. I don’t know how you do it. And thanks for the work you do here and the reliable advice you give.

Bob

 

Hi there Bob,

First off, I have yet to read a lame question. Plenty of lame answers but no lame questions. As my Dad always said, there is no such thing as a dumb question, only dumb mistakes from not asking.
It is normal for both cooling fans to cycle on and off every time the A/C compressor kicks on. Both fan relays are controlled by the PCM and that is just the way it was designed by Mazda engineers. A variable or at least two speed fan system would be nice but that is more expensive to build into a car and well, the Protege is Mazda's entry level vehicle so it gets the cheap stuff. Not that they are not a very good car mind you.
Every 20 seconds sounds like a little too much cycling so you may have a system that is either under or overcharged. Both fans come on to provide even cooling across the surface of the condenser. Cooling of the condenser is one of the more important aspects of getting good cool air inside the car. You could disconnect one of the fans but you might see a small drop in A/C performance especially at low speeds or idling. If you are going to disconnect one of the fans make sure you disable the AD FAN or condenser fan. That is the smaller one on the passenger side. The larger fan is the primary cooling fan for actually cooling the engine off. With A/C off it should come on at 208'F and stay on untill coolant temp drops to 201'F. If for some reason the primary fan is unable to achieve this cooling (ie fan or relay failure, restriced radiator, or just too darn hot outside) then the secondary fan will not come on untill coolant temp hits 235'F. Secondary fan will turn off when coolant temp drops to 226'F. As you can see from those temperature ranges, you most definitely want the Primary to be operational. If you decide to disable the Secondary fan on the passenger side then might be a better idea to remove the AD FAN relay in the under hood fuse box rather that disconnect the fan. That way if there is a Primary fan problem and engine start to overheat, your daughter can simply reinstall the removed relay that could be stored in the glovebox rather than fighting a hot radiator trying to reconnect the fan connector. Just an idea anyway. Pic of the AD FAN relay is first below. The relay just to the left of it is the Primary fan relay.
There should be very little to no rpm drop when the A/C kicks on. Most have very little vibration unless the compressor is working too hard and dragging the engine down (another syptom of overcharge) or a motor mount is sagging. If the hood is rattling badly and will stop if the hood release is pulled then the rubber stoppers at both front corners are a bit collapsed. Somewhat of a common occurance with the older Protege. Second Pic below is of the stopper on the drivers side and passenger side is in similar location. They are adjustable so give each a 1/2 turn or so counterclockwise.

[IMG]local://upfiles/1377/81DEF0DD9C234AE78ED78698C2764FB6.jpg[/IMG]

[IMG]local://upfiles/1377/D5170B98DBF74586AC1BF440BDB818E2.jpg[/IMG]

 

Well... what can I say? As you have done with so many other people in need of help, you answered ALL my questions with clear, concise, thorough, intelligent, interesting, just-plain-good advice. This is highly unusual in today’s world of rampant BS if you know what I mean. I cannot thank you enough for the information and your speedy response.

I was so impressed by the way you addressed all my concerns that I couldn’t help but make a donation to you and your compadres at MazdaForum to show my appreciation. Thank you kindly for everything.

Bob
Marble Falls, Texas

 

Thank you in return Bob for that nice response. Glad I was able to shed a bit of light on the subject. Take care and give a post back anytime. Hope your daughter gets off to college ok. Am sure she will with a Father that takes that much interest in making sure that she is safe and in good hands like yours.