Why won't my heater shut off? I can dial the fan down to the lowest blower setting, but it won't shut off at the Off button. The temp. is therefore set at 83 degrees. The modes work i.e., floor, defrost, etc. thank you.

The most common reasons an INFINITI I35 heater isn't working are a broken heater blower motor, a problem with the thermostat, or a failed heater blower motor resistor.

INFINITI I35 Heater Is Not Working - RepairPal.com

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check the resistors in the blower housing for burn out. If it is a module replace the module

Automatic or manual heater control. Automatic is the one where you set the temp to a certain degree and it maintains that temp. Manual has the temp control on a dial or levers.

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By the blower motor ,there's a resister,replace.

Does this have auto temp control where you set the temp number or does it have a knob you set 1-5. I'll bet you have auto temp. and you need to replace the blower control module under the hood.

probably has a bad blower motor resister

you might check your switch sounds like to me that your two lower speed sides of the switch maybe burnwed out.

check dial switch, check valve that lets water run through heater core

Usually when the blower fan only operates on hi speed, its because of a failed blower motor resistor. You still have hi speed because on hi, the power going to the blower motor goes directly to it, as opposed to the lower speeds, when the power is routed through the resistor, thus lowering the voltage, which in turn lowers the speed of the fan. The resistor is usually located near the blower motor itself, under the hood back near the firewall.

some where on the heater lines or by the heater core there should be a gate valve. However is your heater fan fluctuating ( blower motor ) with your R.P.M.s ? if so then check the tension on your altenator belt.