I have a problem that the AC unit will blow hot air when both temperature controls are set to full cool. Looking around the forum it was suggested that the duo-valves were stuck.
https://www.crossfireforum.org/forum...ggestions.html

So what does the duo-valves have to do with the AC? Looing at the ducting for the HVAC system, it's important to understand the airflow. Looking below at the diagram the heater core is before the AC core. That means the hot air is blown through the AC core. In a way the heat will take precedent over cool this is very helpful when defrosting the car where you want to heat and extract moisture out of the air.


HVAC ducting and routing


Of course looking in the manual you can't find anything called duo-valves. I eventually found what is the proper name: Coolant circulation valve.

Coolant Circulation Valve

So what is the Coolant Circulation Valve? Look at number six in the below diagram. Coolant refers to the engine coolant to cool the engine. When it's run through the cabin heater core, it's actually hot water. There are two valves that allow water to flow through the heater core for the cabin air. Since the heat can be controlled for the passenger and driver there are two valves.


Hot water circuit for engine coolant

The unit has two solenoids and two valves that can wear or get stuck. If you have the AC pump turned off and the temperature selectors turn to full cool and the hot air comes out of the system, the the coolant circulation valve needs maintenance. You can buy a rebuild kit for the unit off of amazon.

Rebuilding the unit is easy. Pull the electrical wire. Open the antifreeze reservoir cap to release the system pressure. Use a splined screwdriver to remove the five screws.

The Duo-valve or coolant circulation valve

You can just pull the top.


No top with valves down in their seats

Here is a picture showing a worn valve.

valve

Use the kit and remove the oval seal. Clean all surfaces. replace the valves back into the seats. Carefully align the solenoid shafts onto the valves and place down. Tighten all the screws. Put the wiring back and test. If that does not work. Then the solenoids are bad and the unit will need replacement. Here is the instructions on removing the unit.


removal instructions