You can usually hear the intermittent humming of the compressor throughout the day. Testing. If a compressor clutch on any vehicle has failed, the cause may be low voltage to the clutch. Other inputs that can affect when the fan relays are energized include engine temperature, transmission temperature, intake air temperature and A/C operating pressure. However, with the ignition off, the thermofan switch and relay would both have to fail to cause the problem. The relay is the component that fails most often, so be sure to test the relay as well as its power supply and ground connections. For example, a low power circuit in a car that commands the high power headlights to come on would send the command through a 4 terminal relay. Check the power. Electronic types might freewheel, but most fan clutches should spin with a little effort. If any of the subsystems inside the IRCM module have failed, the whole module must be replaced. How to Tell if Cooling Fan Relay is Bad. What goes bad on a relay? Hook the fan directly to car battery, if it works, try to hook the fan just before the relay, and if it works, test the relay by connecting a 12v current to the relay (to the connector that makes the relay conduct current, usually there is a diagram under the relay) if the fan spins while in place, the relay is good. 1. If the cooling fan motors burn out or fail, the cooling fans will be disabled. Because as was mentioned earlier, most cars use the same fan for the radiator and A/C condenser. Cooling Fan Relays and Fuses. Locate the circuit breaker and ensure it hasn’t tripped. Some vehicles will have a high-speed relay and a low-speed relay. If You Think The Problem Is The Cooling Fan Relay, Test It ! The mechanic will check to see if all the wires to the fan are properly … Turn on the ignition switch, and using your wiring diagram, locate the wire for the ground side of the relay coil. The engine control module provides ground to the fan relays when cooling is needed, and a dropping resistor is located inside each fan motor for two-speed operation (that’s why each motor has two power input terminals but only one ground terminal). If the 2 lines are depicted as not connecting at the circle or dot, the relay is a normally open (NO) relay. Im just telling what I read. This unit controls the both fan relays, compressor clutch relay and the fuel pump relay. Required fields are marked *. If one or both fans fail to come on, the lack of additional cooling provided by the fan may cause poor A/C cooling performance, and it may cause the A/C compressor to overheat and fail. When you're driving, air flows through the car radiator to keep your engine a normal temperature. The quickest way to tell whether or not the electric fan(s) are working is to start the engine, let it reach normal operating temperature and then turn the A/C on. If no power is observed at either 87 or 30, the fusible link or maxi fuse has shorted. Step 2 - Next, reinstall the relay while keeping the wire strand inserted and clear of any other terminals or metal (ground). Shake the relay in your hand and listen for a rattle. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located). Want to master Microsoft Excel and take your work-from-home job prospects to the next level? They should both come on in just a few minutes on a warm day. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located). Disconnect electrical connector for the thermofan switch. Try moving the fan forward and backward. Cooling fans do not come on. Phone: 08060675824 Your email address will not be published. Start by looking for the blower fan resistor. Turn the ignition to the "ON" position and jump terminals 87 and 30 the relay is now jumped and the accessory should activate, if so the relay has failed. I think they’re supposed to be on when the AC’s running. If the power is fine, check to see if there is proper voltage. Check the Fan. If the cooling fan relay is bad on 1989 Toyota Cressida will it keep the cooling fan from coming on and make the car to run hot, Posted by christine malone on Sep 18, 2018. I believe they’re supposed to default to “on” if there’s not signal from the coolant temp sensor. Then it's a problem with the heat censor. The most common symptom of a faulty cooling fan motor are cooling fans that do not come on. If the cooling fan motors burn out or fail, the cooling fans … On this vehicle, you should use a scan tool to see which of these inputs is energizing the fans and when. Defective fan relay. The most obvious symptom of a bad PWM fan relay is that your Jeep is gonna' overheat. You can do this at the transformer, checking for a fuse in the low-voltage circuit. Electronic types might freewheel, but most fan clutches should spin with a little effort. If resistance is high, the coil may still be working but it is failing, or it may not work when electrical loads are high. Clicking this will make more experts see the question and we will remind you when it gets answered. Dual relay. They are hooked to the 50 AMP fuse in the glove box #36. on most ford contour cars the cooling fan only runs when the motor reaches a certain temp. Once this happens, your air conditioning unit is at … i reall dont want to spend over 300 bucks for new fan. Comment; Flag ; More. One of the first symptoms commonly associated with a bad or failing cooling fan relay is an engine that runs hot or overheats. If the fan spins more than three times, you may have a bad fan clutch. Be the first to answer! The filter is mounted in a hot area and tends to fail, preventing the cooling fan from operating. Somethings not right - you can hear the compressor start to growl at idle, pull the idle down, then cycle off. If you hear something rattling inside, the relay armature is probably broken. Both fans run continuously. I did a search for this and read the aux fan is only for the A C. Someone said the clutch fan is sufficient for engine cooling and there was no need for an Aux fan, this was only for AC condensor. If the fan relay has failed, it will prevent the compressor clutch from engaging and there will be no cooling. Bad temp. How do you know if your fan relay or motor is bad? (This test will not activate the A/C Condenser Fan.) Here’s how to tell if your cooling fan isn’t working, what you should do about it and what the problem might be. It may cause the fan to cut in and out, or not come on at all. The cooling fan in the engine compartment should turn on to pull air through the radiator and A/C condenser. One symptom here of a failed module is a car that cranks but won’t start because the fuel pump isn’t getting any power through its relay. Watch this video to figure out how to diagnose problems with the cooling fan relay on a Chrysler. If fan stops, the thermofan switch is most likely bad. Replace the relay. If this relay fails (which it often does because of the load it carries), the fan may operate at high speed but not low speed. See how to use continuity checks to identify the problem and make sure that the fan motor, electronic control board and the wiring that connects them are work correctly. If the fan spins more than three times, you may have a bad fan clutch. The cooling fan in the engine compartment should turn on to pull air through the … how can i tell its not burned up or how can i test this problem? If the test above fails to activate the Radiator Cooling fan, then the 30 amp Cooling Fan fuse in the Main Relay and Fuse Box is blown, or the Cooling Fan Relay or Main Relay has failed open, or the fan motor is bad. Step 1 Open the hood and/or fuse compartment so … The quickest way to tell whether or not the electric fan(s) are working is to start the engine; let it reach normal operating temperature and then turn the A/C on. Fig. If the cooling fan motors burn out or fail, the cooling fans will be disabled. Use a voltmeter to measure voltage to the clutch. The module is mounted on the radiator shroud and is exposed to a lot of heat so failures are common. The only tool required to check a relay is a multimeter. Temperature gauge on the instrument cluster is maxing out. 1 2. Answer . Spin the fan. Inspect the resistor visually. Ford cooling fan controllers (late 1980s and early 1990s Mustangs and other models). If You Think The Problem Is The Cooling Fan Relay, Test It ! The engine may also run hot and overheat, too. Your fridge also contains a condenser fan typically situated next to the compressor unit. The problem here is the cooling fan circuit uses a radio frequency filter mounted on radiator fan shroud. Engine overheating or poor air conditioning performance can be caused by an engine or A/C condenser cooling fan that fails to come on. If the cooling fan relay is bad on 1989 Toyota Cressida will it keep the cooling fan from coming on and make the car to run hot, Posted by christine malone on Sep 18, 2018. A wiring issue. Chrysler Neon. Some folks will tell you that a bad cooling fan relay can also cause this. Ford integrated relay control module (IRCM) (introduced in 1986). I know nothing of these things. Consequently, the compressor clutch may only get 9.8 volts instead of full battery voltage causing it to slip, overheat and fail. This type conducts current when open and when closed in two different circuits. All Rights Reserved. Went out of town and left my fan on for 5 days straight by accident. The two fan fuses (30A and 40A) are in the same location. Chrysler LH cars (since early 1990s). Three fuses in the power distribution box protect these circuits. Jump-start your career with our Premium A-to-Z Microsoft Excel Training Bundle from the new Gadget Hacks Shop and get lifetime access to more than 40 hours of Basic to Advanced instruction on functions, formula, tools, and more. Symptoms Of A Bad PWM Fan Relay. I assumed a blend door was bad, but noticed the electric cooling fans were not coming on. If it’s not working, the fan won’t turn on when it needs to, which means the engine might overheat. But if you stop, for example in a traffic jam, your engine has to use an electric cooling fan to force air through the radiator. How to Tell If Your Home Thermostat Is Bad. The relay is hot because it's being "switched" on and electricity is running through it but it's not being drawing by the fan motor. The cure here is to add a separate relay for the compressor clutch so the clutch can draw full voltage from the battery. Cooling Fan Relay Diagnosis Now for the relay, or relays. You'll also see one or all of the following symptoms as the engine overheats: The electric radiator fan motor does not come on. Operation by using an internal resistor to drop voltage to the A/C and turn down. Again, this is a normally closed ( NC ) relay high and low ) fan by! Civic … shake the relay is no or NC during further Testing provides two-speed ( high low! Nc during further Testing a warm day a repair manual can tell you that a bad sign Chrysler vehicles the. 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