Hey guys, my 92 Z vert 305 tpi my a/c controller only works on defrost. I think I hear a small hissing like maybe a vacuum leak. Let me know what is common to go out on these and what parts would be good to change while I have it partially tore down. The warm-cool arm on the controller is very hard to slide also. The fan blows well and changes speed like it is supposed to and it does not turn on the compresser and the compresser is new. Thanks in advance.

 

if the contorller doesnt get vacuum it work on defrost only. common problems are vacuum leaks on the hose that plugs into the back, or vacuum leaks on the hose under the hood. there should be 2 vacuum lines comming out of the firewall near with the ac wiring. one goes to the diverter valve, the other supplys vacuum to the control head.

 

I have the diverter valve hose hooked up but where is the supply hooked to? Can you buy the new vacuum assembly on the back of the controller and if so where? If the vacuum assembly on the controller is leaking that would account for the hissing I hear in the dash so it is probably dry rotted and needs replaced.

 

usually its just the supply hose that leaks. it gets supply from a full manifold vacuum source and the source hose should go into the firewall as the same spot for the diverter valve hose. they go into the loom for the ac wiring.

 

I am finishing up my LS 1 swap and am getting ready to figure out the final odds and ends. I have the two hard lines sticking out of that loom on the fire wall right by the ac box, so I am guessing I need manifold vac to one of those to make the heating controls operate? My heater core hoses no longer have a diverter valve in line so the other line will be unused? Will that be a problem with running AC down the road?

 

right, one line supplies vacuum to the ac controls, the other can just be capped off. to figure out which is which, hook vacuum up to one and see if the ac will switch to anything but defrost. if it doesnt then you got the wrong line.

 

Do you think lack of diverter valve will cause issues with running the AC, blowing cold air over the core?

 

i dont have one and i havent had an issue yet. the ac might just be a tad bit warmer than normal.