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A/C and Engine Fan Stays ON
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southensoldier
User
Sep 2, 2009, 9:25 AM
Post #1 of 4
(1574 views)
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A/C and Engine Fan Stays ON
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I have a 92 Honda Accord Ex....when I start the car the a/c fan comes on. I know the engine fan is suppose to but not the a/c unless I turn it on. Or is the engine fan only suppose to come on when the engine reaches a certain temperature???? The other thing is that sometimes the car will stall out when I slow down or come to a complete stop. The engine will flutuate under 1K rpm's and oil light blinks and if I dont press the accellerator it will stall out.
So when I think its about to stall I just put it in neutral and press the accellerator to keep it from stalling. But while just running in idle/park it will not flutuate, only when in gear and sometimes will not stall even if dont press the accellerator.
Are these problems connected some how???
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 2, 2009, 9:37 AM
Post #2 of 4
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Re: A/C and Engine Fan Stays ON
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No, they are not connected.
For the stalling problem.......
You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.
On the cooling fans, here's how they work
Cooling fan operation is controlled by the fan timer module which monitors signals from coolant temperature sensor, and A/C compressor clutch operation. Timer operates cooling fan by controlling voltage applied to fan relay control coil. Battery voltage is applied directly from main fuse to relay switch circuit and timer bypass circuit. Voltage is applied to timer main circuits through ignition switch start and run contacts. Timer module controls voltage applied to relay control coil circuit, and control coil circuit is completed to ground through either thermo sensor or timing module. When current flows through relay coil circuit, relay contacts close and voltage is applied to cooling fan motor.
During normal operation, voltage is applied to relay coil by timer module and fan operation is thermo sensor controlled. When coolant temperature is approximately 190°F, current flows through relay coil circuit and voltage is applied to fan motor. When coolant temperature is below 190°F, thermo sensor contacts open and cooling fan does not operate. When A/C is turned on, timer energizes relay coil and cooling fan operates as long as clutch remains energized.
When engine is turned off, timer module remains energized and monitors signals from coolant temperature sensor. If underhood temperature exceeds 220°F, timer activates fan relay and cooling fan is energized. Cooling fan will operate for a maximum of 15 minutes after engine has stopped or until underhood temperature drops below 220°F.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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southensoldier
User
Sep 4, 2009, 8:52 AM
Post #3 of 4
(1552 views)
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Re: A/C and Engine Fan Stays ON
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so wats the cause ???
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Sidom
Veteran
/ Moderator
Sep 4, 2009, 1:40 PM
Post #4 of 4
(1547 views)
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Re: A/C and Engine Fan Stays ON
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HT pretty much gave a good description of how the cooling fan circuit works.
You are correct in assuming that the cooling fan should come on when the car reaches a certain temp, constantly running isn't a super critical problem as long as you have a good t stat, definitely better than not coming on at all...
For the stalling problem make sure your throttle body is clean. Get in there with a little brush & some throttle body cleaner, open the throttle plate & clean all around in there, run it & shoot some down the throat...
Those have a problem with their IAC motors (Idle air), they run coolant thru them & the gears corrode & get stuck. One thing they do if it's jammed up is it will surge pretty good when in park or neutral.......... I've take em apart, cleaned them up & then greased them & have had some good luck (and some bad, more good than bad). They are expensive to replace.......
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