I know the LT1's have the feature where at WOT the A/C cuts off, but mine does it with even the slightest bit of throttle and it's really annoying!! Anyone know what's wrong?

 

You have a vacuum leak. There are four doors inside the HVAC duct work that deflect the air to the appropriate vents when selected. The default position is feet and defrost. That is, when there is no vacuum (as in limp home) the vents will default to feet/defrost. Any other position selected has to be held open with vacuum. In your case (as I had too), when you stomp on it, vacuum level goes down, and the door that was being held open closes. The default door, feet/defrost, takes over. It seems too you that the blower is slowing down (as did me) but in actuallity, the blower is staying the same speed and the vents are switching to the feet and defrost position.

So what do you do to fix it? Every person probably has their own way to do it but I'm from the simple (lazy) school and quick too since we charge by the hour. I like to split the vacuum system into 2 sections. 1 in the engine compartment and the other in the cabin. Start by pulling off one of the hoses,(I think it's the bottom hose) on the check valve at the fire wall near the PCM. If you get a quick release of pressure and hear the air rushing in, chances are good the system in the engine bay is ok.

What you did was let air back into the vacuum resevoir located behind the front bumper. If there were a leak upfront somewhere you would not have heard the rush of air back in when you pulled the hose off. In that case, you will have to locate the source of the leak somewhere between the check valve and the canister.

If air does rush in when you pull the hose off, the problem is in the cabin. What I feel is the easiest thing to do is remove the hose cluster from the HVAC control **** assy and test each individual hose going to each door (called actuators).

At the control is 5 hoses, a black one provides vacuum from the engine and 4 colored ones for each actuator. Check the black one for a vacuum level near 20 PSI. I used a mityvac brake bleeder. If you rev up the engine while monitoring the black hose and the level drops off, you know the problem is back toward the engine bay. If it is ok, put the vac on each colored hose and draw a vacuum and see if it holds. The one that does not hold is the problem.

 

What if you're having the exact opposite problem?? With throttle movement, the A/C directs through the upper vents like normal, but if you maintain a steady state of throttle (I.E. cruise) then it reverts to the default. Any ideas?

 

If by throttle movement, you mean getting on and off the throttle, your off throttle conditions generate a lot of vacuum. Depending on the load on your engine at a steady cruise you may be depleting the vacuum supply. I would still look for a leak.

 

When I was switching out my termostat last winter (160-180) to get my heat flowing hotter I broke a line that runs from the right side of the intake manifold under the TB and to the other side of the engine. I tried to put it back together but did a really crappy job. Could this be my problem? And where can I get a new line from? I fixed it with some rubber hose, but haven't checked it in a while. I hope this is it!

 

A commen problem is the check valve located near your passenger side compartment in the engine bay. Look at shoebox's diagram.