blower motor stays on all the time

[abchubs]

I am having problems with my 1999 Infiniti QX4 Heating/AC unit. When the key in and the Heating/AC unit is off with nothing is on the Climate control display the blower stays on like its set on high. Other than that the climate control works fine but it wont control the fan speed even thought i set it to low it blows like if its on high. It cools,heats and changes setting but no control over the blower.

I have checked the relay for the blower.

Can anyone help!!!

Thankyou,-abchubs

[Q451990]

Sounds like the resistor pack that screws in to the evaporator housing. The switch works through this to control fan speed, but when they fail it's typical for everything to run wide-open. I'd call Joe and order a new one... easy to change, and he should be able to confirm that this is the symptom as well.

Joe offers a parts discount and is the parts guy at Infiniti of Scottsdale - 1(888)216-5328 or http://www.infinitipartsusa.com (but calling works faster).

Heath

[abchubs]

Thank you Heath

i look in to that and keep u guys posted.

-abchubs

[Q45tech]

Continuously variable fans have a transistor pack in place of the old style resistors.

Much like the fuel pump/controller failure mode the worn out fan motor starts drawing too much current, stressing the transistor beyond its design limits..........eventually the unit fails.......and all you have is wideopen speed.

The fan motors really should be replaced at the same time but most just change the less expensive transistor unit which may last a decent amount of time.

Max fan speed bypassses the transistor, but 7/8-3/4 speed is the stress speed.

[NISTECH]

on those systems too the fan stays on even when you turn the system of. and as Q45tech said you can replace the amplifier and it will last awhile but it will be sure to happen again if the motor is still drawing excessive current on the system.