85 BRAT, where is AC thermostat? Wiring Diagram pic

[mkoch]

85 BRAT, where is AC thermostat? I want to locate every component.  

 

Pic

[GeneralDisorder]

Likely somewhere on the evaporator case buried in the dash. It doesn't appear to be in-circuit unless you select blower speed one so I would ignore it for the purposes of troubleshooting. Run the fan at level 4.

GD

[azdave]

On 7/10/2022 at 10:21 PM, GeneralDisorder said:

Likely somewhere on the evaporator case buried in the dash. It doesn't appear to be in-circuit unless you select blower speed one so I would ignore it for the purposes of troubleshooting. Run the fan at level 4.

GD

The schematic can mislead you but the circled thermostat is actually in-circuit at all blower speed selections. If the blower relay is engaged and the blower is running, then power will be going to the A/C thermostat regardless of the blower speed selection. It's very likely the thermostat is a capillary tube style switch used to prevent the evaporator from icing up when the A/C is running on a cool, damp day. Those devices are usually adjusted at the factory to measure the evaporator fin temperature (not air temperature) and are not easily accessible after the evaporator is installed. I don't have a Brat so making some assumptions here based on other s I know. Some of them look like this with the far end of the coiled tube stuck into the evaporator fins.

 

[mkoch]

Azdave, thanks!

 

[mkoch]

12 hours ago, azdave said:

The schematic can mislead you but the circled thermostat is actually in-circuit at all blower speed selections. ...

 

With the battery disconnected, I tested the resistance from the AC relay, through the thermostat and fan speed switch, to ground.

 

You're right!   The thermostat is part of the circuit in the four fan speed positions.

Thank you for the response!

 

 

12 hours ago, azdave said: