The Blower motor on my AC unit turns off at random times while the outside unit continues to run which is causing the coil to freeze up. Turn the blower motor OFF (when the heat exchanger drops in temperature after a heating cycle) Turn the furnace blowers off (when the heat exchanger hits dangerously high temperatures) That said, if your furnace fan limit switch is damaged or has been tampered with, it might allow the fan to run even after the heat exchanger has cooled off. Find this article useful? When the blower motor relay does begin to fail, the vehicle will usually display a few symptoms that alert the driver of a potential problem that should be serviced . I have replaced them in both of my current 02's and a previous 01. and you think that module being bad would cause my problem?? In the shorted mode power ties to the blower motor and makes it run regardless of the ignition switch position. If you live in the Minneapolis-St. Paul area, schedule your appointment with MSP today. Set the multimeter to test continuity, measured in ohms, and touch the tips of the multimeter probes to the two contacts on the motor. Material may not be copied or reprinted without written permission. The Mercedes has a series of sensors that, working in concert with a computer, maintain a constant climate in response to the settings on the console. Created by Rocket Media, Minneapolis Saint Paul Plumbing Heating Air, letting a professional repair or replace the switch, The Scary Way Your Furnace Could Start a House Fire (and How to Prevent It), Ductwork that is leaky or designed poorly, Abnormally low temperatures in the heat exchanger, Abnormally high temperatures in the heat exchanger. Power to the blower motor is fed through the blower motor resistor, so if it fails or has any issues power can be cut off to the motor. I can not tell from blower speed which mode is powering the blower. GLENN F. POTTER. Ford blower motor resistor problems remain the most common solution to interior fan malfunctions on Ford cars and trucks. Pull the two wires off the motor terminals on the blower assembly. The blower motor automatically comes on when the system senses the temperature "in the car" is at or above the selected temperature on the dash. The cabin air filter is fairly new, less than a year. I recently noticed that the blower motor in my wifes 2002 V70 is running, even when the the key is out of the ignition. This is relatively common problem of the the full sized Chevrolet, GMC and Cadillac trucks with auto a/c controls. If so, it’s most likely caused by a bad fan limit switch. With PWM, the voltage to the blower motor is switched on and off electronically like a digital signal. Take your temperature in the car "up" and the blower motor will shut off, then turn off the system. Recently on a long trip, the blower for heat simply went out. The A/C blower motor cycling on and off is definitely the A/C system informing you of a problem. There are two; one for the front (dashboard) fan and one for the rear (center console) fan. Flame sensor. The flame comes on and the blower does not. I have a 2006 Pontiac G6 GTP and the blower motor will sometime turn back on after the car is shut off. For a week. The A/C would be blowing like normal and suddenly shut off and come back on a few moments later. It's possible your furnace will run when the blower motor is off; however, that's rare. Consider that the purpose of gas furnace is to warm the home, and realize that it is the blower motor that actually takes that heat and directs it from the very isolated, insulated furnace and in to the actual home. Blower motor doesn’t shut off. But before you call a professional, two things you can do to try and solve the problem are: 1. Sometimes it happens when I hit a bump then it will start blowing air for 5 second then switch off for a few seconds then switch back on. 50 seconds, then off for approx. The FAN OFF setting lets the furnace blower continue to run for an interval after the furnace burner has turned off, but will shut the blower off after the heat exchanger has been cooled down to this temperature (usually 90 °F). In normal operation, your furnace blower fan should come on 1.5 to 3 minutes after your thermostat calls for heat and should turn off several minutes after the heating cycle ends. If you have a three or four speed blower motor, remove the blower motor relay. If voltage stays constant the problem is in the motor. Once the flame goes out the fan turns back on. The interior fan is powered through two separate fuses and a blower motor relay. More modern gas furnaces will have a control board. Your blower should run constantly until the heating cycle ends. and kicks of the fan kicks off. Is your blower turning on/off when your furnace isn’t heating? The mode switch sets the off-on by grounding the motor when in positions 1-6 (right dial inside the control box at the bottom of the diagram). Test the fuse, with the ignition key on, using the 12-volt test light. Report; Follow; Asked by pshawn Dec 16, 2014 at 01:31 PM about the 1999 Ford Expedition 4 Dr Eddie Bauer 4WD SUV. I think it just fails .... like it does in every other Nissan. When your furnace isn’t actually heating, though, your furnace blower shouldn’t be running at all. When your furnace isn’t actually heating, though, your furnace blower shouldn’t be running at all. The ac/heater blower motor goes on and off intermittently. For the past 6 weeks it would randomly go off, I would turn it off and try again after some time. An air-conditioner with an overheating blower motor may shut itself off to prevent damage and electrical hazards. Set the multimeter to test continuity, measured in ohms, and touch the tips of the multimeter probes to the two contacts on the motor. Unfortunately, you’ll need a professional to solve most of the problems listed above. If you’re still noticing that your blower turns on and off constantly during a heat cycle, you’ll need to have a professional inspect your unit to find the problem and correct it. The furnace blower fan cycles on and off AFTER the call for heat has been satisfied and AFTER the BURNER has TURNED OFF. FAN-ON: the middle setting on the fan limit switch dial (green arrow) is the "FAN ON" temperature. Is this common on this car? Comment; Flag; More. I have already replaced the blower motor with new GM part, but the problem persists. ... With the thermostat in the OFF position, the blower motor starts as soon as power is supplied to the furnace controls. A … Start by turning the furnace off, turn your thermostat to “fan only,” and wait a few minutes. Save Share. But when I re-closed the safety switch, the blower fan again started. Postby CanuckQx4 » Sun Nov 06, 2011 8:24 am, Postby yeldogt » Sun Nov 06, 2011 7:51 pm, Postby CanuckQx4 » Sun Nov 06, 2011 9:54 pm, Postby yeldogt » Mon Nov 07, 2011 5:13 am, Postby fueler » Mon Nov 07, 2011 11:17 am, Postby CanuckQx4 » Mon Nov 07, 2011 3:09 pm, Postby yeldogt » Mon Nov 07, 2011 4:46 pm, Postby CanuckQx4 » Mon Nov 07, 2011 5:21 pm, Postby yeldogt » Tue Nov 08, 2011 6:09 am, Postby CanuckQx4 » Thu Nov 10, 2011 5:13 pm, Postby ARKQX33V6 » Fri Nov 11, 2011 5:26 am, Postby yeldogt » Fri Nov 11, 2011 6:15 am, Postby CanuckQx4 » Mon Nov 14, 2011 9:34 am, Return to “Nissan Pathfinder Forum / Infiniti QX4 Forum”. If you have a vehicle with climate control system and a variable speed blower motor and the blower motor won’t shut off and stays on HIGH with the car turned off and the key out, chances are the blower motor motor control processor is toast or the HVAC control module is damaged. Jeep Garage - Jeep Forum. So, what can you do to stop your blower from constantly turning on and off during a heat cycle? SPONSORED LINKS. I turned it off, and 20 cold minutes later tried it again, it worked. First off some background info to get you in the right mode. The only way I can stop it is to unplug the blower motor connector from the blower motor control module (resistor). As soon as the heat exchanger cools down, though, the burners turn back on (because the thermostat is still calling for heat) and the process repeats. I own a 2001 Jeep Grand Cherokee Limited. The only way to test and see if it is a blower motor relay would be to test with a voltmeter to see if the motor is getting 110 volts to the motor when it starts going off and on. I am assuming that the blower motor runs on high even with the key off? Don't pay much for the used part ..... it too my be original. Mazda CX-9 - Blower Motor Stays On After Key is Turned Off A few weeks ago, our 2007 Mazda CX-9 Grand Touring model started doing something rather peculiar. This was becoming a big problem. The first step is to lower the passenger side hush panel under the dash. If overheating is the problem with your blower motor, then the solution is to turn the unit off and let it cool down for a while before switching it back on. I’ve replaced the ignitor and flame sensor with parts from Arnold in the last two weeks. Problem: The heater comes on, the gas lights, the furnace warms up, the blower starts then abruptly the gas cuts off, the gas immediately reignites, the blower comes back on, the heater heats the house nicely.The Heater has never quit, but the whining noise when it relights is driving me crazy. Diagnose furnace blower problems: this article describes what to check if the warm air heating blower fan cycles on and off after the call for heat has stopped, that is after the room thermostat has been satisfied. Minneapolis Saint Paul Plumbing Heating Air So if your furnace blower is turning on and off when the furnace isn’t in a heat cycle, it usually means the fan limit switch is defective. The blower motor side connections seem fine, no overheating and the bearing spin nicely. The relay on/off command by the thermostat and will turn the fan on and off. Is if I put the key out of my truck and the is. Fan and one for the blower motor would turn back on may not be copied reprinted... T shut off and come back on if that fixes the problem is in the two! Key in and out? electrical hazards and a blower motor keeps going have it! Setting on the driver or passenger side hush panel under the dash was turning off if! 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