Besides the heater core leaking, on long trips the AC would no longer blow. The fan works fine but something stopped the flow of cold air on long trips. While I have the entire box out I would like to somehow test this actuator to see if it's the culprit.

On a side note, every once in a while I would hear something like running water coming from inside the box while the AC was on. Maybe there was such extreme condensation that the AC caused the water to freeze and block the door. But the next day after the AC would work fine. Weird.

 

Just apply vacuum and see if it activates.

 

Yeah do this. Also, I don't know what year, but since it's vacuum I would assume its a 98-2000 correct? If so, vacuum doesn't control hot/cold anyway. That's a cable. Vacuum controls which set of vents to use, and it controls whether or not it's outside air or recirculated (Max A/C position) it's possible it's freezing up. These systems have expansion valves in them, not orifice tubes. Because of that, they're never supposed to freeze up, but they will. Mine used to freeze up if I was going down the highway for a long time with the fan on the low setting and it wasn't too hot outside.

 

 

The condensation freezes up on the evaporator itself. That's why air flow stops, it always travels through the evaporator. Turn the A/C off for a minute and it thaws out, you'll notice airflow comes back, turn A/C back on. It was probably low on freon. When it's all back together, put the exact amount of freon in it that it calls for and it shouldn't freeze up anymore

 

That makes complete sense! I noticed when I pulled the top of the box off all the mesh that was fitted to the evap core was disintegrated and at the bottom of the box. It's probably what kept the frost from blocking the air flow. The new core didn't have that. Now I'm thinking maybe I should open the box back up and put some kind of foam on it.

 

It couldn't hurt if it's still out of the truck. It's probably important. Warmer air will go around the evaporator maybe if it's not there. As far as if you wanna test the actuators and don't have any type of vacuum pump, just use a piece of tubing and tie into a vacuum port under the hood and attach it to the port of the actuator. It should then move while the engine is running

 

So everything is up and running and all the vents work fine and the heat works great! Going to change the antifreeze though. Want fresh fluids running through that block.

The only thing I haven't done is recharge the AC. This doesn't harm the AC compressor in any way as long as I don't run it correct?

 

I wouldn't think so, but I'm not sure. There is moisture in the lines now because you opened them. You don't have to charge it but I would at least take the first step and pull a 30-45 minute vacuum on it to get the moisture out. And let it sit for a while with the gauges on it to make sure it's not leaking and allowing new moisture in.

Obviously, it's not gonna hurt the hoses or lines, the lines are aluminum, but I'm sure the pistons and whatnot inside the pump are steel, and it would be bad if they got any rust buildup.

 

Had my mechanic recharge the AC today. They've got the right machinery to do it right. There are certain things that are better off done by the pros.