QuestionQUESTION: I had a 2007 Nissan Quest, recently my A/C had only 1 speed ( high speed ), when i turn on A/C it blow on high speed, and when i turn off, its blow air on the floor, then i check on the back of the club compartment, there is one small black module it locate by the fire wall, when i unplug the connector it stop blowing cold air but the A/C light still lid on the dash board. Is that module go bad or something else?
ANSWER: HI,
I am not quite following your description of the problem. I assume you mean that the fan control for both heat and AC is only working on High for the front unit?
You have not really given me enough information to answer this question but I can try to explain to you how it works if you can answer some of these questions:
1. Is the fan the only thing affected? Does the fan also not work in heat mode?
2. Does it have Automatic or Manual Climate control?
3. Does it have front and rear heating and air conditioning?
A nissan quest uses a 'Variable Motor control module' for both the front and the rear blower motors. They are a four wire block that is suspended inside of the HVAC box to help keep it cool when it is operating a high duty cycle. They are controlled by the climate control module. Instead of using resistors as a conventional system would it uses a control module that pulse modulates current to the blower motors. If you select High the motor gets a 100 percent duty cycle and the cycle lowers with proportion to the request.
If blower motor control on the front motor is what your problem is it is most likely the blower motor variable speed controller. You will have to know how to use a voltmeter to check this and I can explain how to do this if you know how.
Hope this was helpful
Wayne
---------- FOLLOW-UP ----------
QUESTION: The fan blow in high speed with both the heat and A/C mode, climate control is manually. It's had front and rear heating and air conditioning.
AnswerHi,
It sounds to me like the front variable fan speed control module is defective. They are easy to replace and not very expensive. You could try an autowreckers in your area and probably walk away with one for 20.00. If you like I can explain how to test it to ensure you are replacing the correct part but it will take knowledge of a voltmeter and how one operates.
Hope this was helpful
Wayne
I do not like to guess but without proper diagnostic equipment you may be faced with one. The most common failure in fan speed motors is the fan speed controllers or resistor blocks.
