a dc motor runs by voltage the higher the voltage the faster it spins, reversing the power and ground makes the moter fon either clockwise or counter-clockwise i hope this helps if you need more help get bak to me. also must have enough amperage to run the motor, Thanks Ray
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Could be a number of thing's ! Testing the electrical circuit is the way to find out what's wrong . Using a wiring diagram and a DVOM - digital volt ohm meter . Videos on youtube showing how to test it ! Without testing i would only be guessing . Does it work in high speed ? In high speed it by-passes the resistor . If it doesn't work in any speed more then likely the blower motor is the problem !
Air Speed
The HVAC control assembly applies ground to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request:
• Low speed--3 resistors
• Medium 1 speed--2 resistors
• Medium 2 speed--1 resistor
When the operator requests High speed, the HVAC control assembly applies ground directly to the blower motor through the high blower motor control circuit. The resistor card has a fusible link which, if blown, will require that the card be replaced.
Hi Elaine , What make vehicle are you working on ? Most manufactures have a relay for hi speed an have a blower motor resistor for all other speeds . Depending on make vehicle control modules need programming in some cases . Blower Motor Problems Auto Repair Help
Yes,could be your blower resistor is bad,it's right next to the blower motor,it controls the blower motor speed,easy to replace. Duralast Blower Motor Resistor Just took a guess at the model type since you didn't state,wow,high dollar price,guess it comes with a Mercedes,paid about 18 bucks for mine on my 85 Nissan.
It's called the Idle Air Control motor (IAC). It is on the side of the throttle body. This controls the idle speed. What it does is let in a certain amount of air into the engine, in steps. The more it is open the higher the idle speed. The ECM controls it.
You have a radiator fan motor that is not running either due to a thermostatically controlled temp switch,(Located on the back of the radiator) a failed fan relay (in the engine compartment fuse /relay box) or a bad fan motor. You can troubleshoot by checking for 12V DC to chassis ground at the fan motor temp switch. If you have power in you can jumper with a wire the switch wires and see if the fan runs. If it does not run then you need to check the fan relay and motor.
To test the fan you can run a wire from the battery to the fan and another wire to chassis ground to see if the fan runs. If after directly connecting 12V DC to the fan motor and it does not run the fan has failed.
As far as the you either replace it with another one or... have to figure out which 2 wires control the fan motor and jumper them out to see if the fan runs.
Most of the time this is a bad "blower motor resistor". It is easy to replace. You will find your behind the glove box in the ac/heater (evaporator) housing. Below is a pic of the resistor as it is seen from behind the glove box. 1. resistor assembly. 2. harness 3. fasteners (2). 4. lower edge of glove box. (open).
i have been having that same exact problem with my 2002 grand prix for over a year now, and when my ac is on the lower setting the it doesnt work plus the headlights and lights on my dash go out. On Max everything works. i changed the blower resistor(about $35), still doesnt work. i changed all relays and fuses related to the ac, still doesnt work. i changed out the actual ac control switch in the dash, still doesnt work. i have changed everything but the blower motor and have asked every mechanic and auto parts retailer i come across and no one knows the answer. The best answer i got is that it is probably a wiring problem like a short somewhere.
R u sure u tested it correctly? There will be a 30 amp fuse usually associated with the blower motor however u need to look at the motor connections with a meter set to ac. These newer cars use a pwm type drive which is a pulsating dc voltage similiar to ac and should vary in amplitude as u turn ur control for speed. If u have that then ur motor is bad and has to be replaced.
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