A/C needs more power

Is it possible the blower speed control isn't working? It's only running on one speed?

 

You will have to look under dash for a air duct hose thats off and just blowing under dash an not out vents?

 

Or blower motor is weak. Restate maybe bad. Evaporater may be plugged with dirt.

 

Don't know if the T6's are like the T8's but check the air intake for the HVAC system, it should be above the pass. side fender, around where the air breather is. Some people install the optional cab air filter over the mesh there. Or if you don't have a cab filter dust can actually take out the fan over time.

 

Check your in-cab filter, if you have one. If it's clogged up, it will slow your flow. The system can only blow out what can get sucked in. A dirty fan will not be as efficient either.

 

I have this issue with a couple older trucks, and the western stars at one customer. If I try the air con and it is blowing warm air out or marginally cooling down the cab, I go under the hood and shut the heater lines off. For some reason this cures the problem.

 

Just don't shut off the line to the transmission cooler . . . Yeah, I did that.