W900L A/C issue update

I’m not familiar with Kenworths, but usually the cold/warm knob controls the heater hoses. If it’s not working, and when it’s set on cold, hot waters still circulating through the heater core, it will cancel the effects of a working A/C system. In that case, turning off the water valves to the bunk, will cut off the heater core, or disconnecting it altogether and looping them together, either way. I don’t see any heater hoses going to the 2 wire thing. What’s it look like underneath? Can you see heater hoses connected to a valve anywhere? Only other thing, I notice the expansion valve isn’t insulated. Did you change the bunk expansion valve? Or just the cab. Either way, the expansion valve needs to be insulated, making sure to cover the round, temp sensor “bulb”, for it to work properly.

 

I would look for ac avaporator coil somewhere under a dash next to blower motor, I bet it is covered with dust and all crap. Same happened to me , I thought AC was low on freon or something but when I took dash apart, ac avaporator was completely blocked, after cleaning it , ac blows ice cold under +40F.

 

I have been through exactly the same thing with both front and rear. Have pretty well had front all apart and cleaned and it still doesn't blow as hard as it use too on high. Ice cold though. I have had expansion valve in sleeper fail more often than front. Pretty well does as your describing. It is best to make sure heater core is shut off. Never had a problem with thermostat knob on wall. On my 93 it turns the blower on and off on heat and cold when it hits set point and + or- 5* or so. My guess is expansion valve in sleeper, especially if it hasn't been changed this season.

 

Where is the expansion valve for the sleeper under the bunk? Haven’t had to work with the different systems yet but I have my front ac blowing in the upper 40s and my sleeper is probably 60ish

 

My guess is it’s the heater core temp valve. Must be plumbed into a heater hose, under the bunk, outside. Can you see anything else going to it? Feel the heater core, is it hot?

 

Looking at a 95 I have behind shop it appears to be the on off control valve for ac as it is directly inline with the tube coming out of top of expansion valve. Look for a loose black and a loose white wire in the bundle leading down to hvac box . I will see if I can find it in my KW wiring diagrams for a number, but the two wire on this one are black and white and spade connected to same in bundle. Looks to me like it could definately stop flow. Probably tied in with thermostat on wall that shuts fan down. I said earlier that on mine the thermostat just controlled fan, but I could well be wrong about that.