While trying to troubleshoot a blower motor not working I found this knob under the dashboard behind the glove box it's tied into a 30 amb relay and seems to almost have a thermocouple coming out of it with a knob that you can turn on the bottom ? I solved the blower motor issue it was a bad blower motor relay, but what is this knob for?
Mystery knob behind / under glovebox
- Thread starter Claytonk
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Solution
Score some back alley R-12 and fire that baby up!
@Spike Strip nailed it. It's a manually adjusted thermostatic switch. This is what was typically put on old school A/C under dash units on vehicles in the 50's, 60's and even today on universal under dash units.
The thermal bulb "senses" the evaporator temp. The knob lets you adjust the point that the switch opens and cuts off power to the compressor clutch. So like mentioned, it does what the A/C amplifier does on most Toyotas.
If you live in a humid area, your evap could "possibly" freeze up if it's set at the coldest position. It's mainly to adjust how cold your air gets. Kind of like the knobs on our dash that might show from blue to red for cold to warm. An analog version.
Usually turning it counter clockwise is coldest but you'll have to try it to find out for sure. You didn't hurt anything by changing it from where it was set.
I have 66 Mustangs with this setup that still work. You can still go to auto parts stores and buy universal ones if yours is bad. They are so basic that they usually last forever. Breaking the tube is the typical failure. Corrosion inside can usually be cleaned out. Pretty reliable units. So are the York compressors. I think they can be rebuilt and many people want them for onboard air compressors.
The thermal bulb "senses" the evaporator temp. The knob lets you adjust the point that the switch opens and cuts off power to the compressor clutch. So like mentioned, it does what the A/C amplifier does on most Toyotas.
If you live in a humid area, your evap could "possibly" freeze up if it's set at the coldest position. It's mainly to adjust how cold your air gets. Kind of like the knobs on our dash that might show from blue to red for cold to warm. An analog version.
Usually turning it counter clockwise is coldest but you'll have to try it to find out for sure. You didn't hurt anything by changing it from where it was set.
I have 66 Mustangs with this setup that still work. You can still go to auto parts stores and buy universal ones if yours is bad. They are so basic that they usually last forever. Breaking the tube is the typical failure. Corrosion inside can usually be cleaned out. Pretty reliable units. So are the York compressors. I think they can be rebuilt and many people want them for onboard air compressors.