HVAC electronic issue

[Shellsh0ck]

Recently my AC controls started acting up.

Manual AC on a 2013 FRS

If i turn the fan to the 1… AC is still off.
2-3-4 speed turns the AC on. But the fan intensity doesnt change

Its turned into an on and off switch with 0 & 1 being off, and 2,3,4 being on.

Any ideas?

[SuperSub7]

Your AC control issue in the 2013 FRS could be caused by a faulty blower motor resistor. It controls fan speeds, and if it's failing, it may not work correctly at lower speeds (1st). You should check out the blower motor resistor.

[Shellsh0ck]

Originally Posted by SuperSub7

Your AC control issue in the 2013 FRS could be caused by a faulty blower motor resistor. It controls fan speeds, and if it's failing, it may not work correctly at lower speeds (1st). You should check out the blower motor resistor.

I just took the resistor out and checked it. Its not at the correct specs but doesnt seem to be so far out as to make the AC act as it does. To clarify the AC is still -off- when switching to 1 on the fan. Not low. The AC light on the heater control doesnt turn on until I switch the fan to 2.

Heres what I measured at the resistor connections vs what its supposed to be IAW the manual:

Ohms b/w 1-4: 3.5 measured (2.92 per manual)
Ohms b/w 1-3: 1.1 measured (0.44 per manual)
Ohms b/w 1-2: 1.8 measured (1.12 per manual)

Would this difference in resistors cause this issue?


Also when I turn the car on (with the fan in 4) you can hear it (assuming the blower?) click, whirr on then stop. It doesnt come on again as you change settings until you turn the car off and on again. It does blow air tho… at the selected temperature, just not at any increased intensity on fan speeds 2,3&4

[SuperSub7]

While these differences aren't extreme, they can affect the performance of the blower motor and the behavior of your HVAC system. Also, each resistor coil corresponds to a different fan speed setting. When the resistance values don't match the expected values, it can lead to inconsistent fan speed operation. This is why your blower motor isn't coming on at higher speeds (2, 3, and 4) until you turn the car off and on again. I think when it comes to the "click, whirr on, then stop" sound you hear when you turn the car on suggests that the blower motor might be receiving power but then encountering a problem that shuts it off and it could possibly be the resistor values. Replacing the blower motor resistor with one that matches the specified values in the manual might be a reasonable step to take.

[Shellsh0ck]

Well i went ahead and replaced the resistor and its still doing the same thing. So whats next?