I replaced my A/C system and it works fine if you like your cold air to ONLY blow out the defroster / defogger jets. What did I do wrong? How can I fix this!?!?! After re-thinking, I did use an air compressor to blow out the cleaner from the lines. What if I uh, er, tug collar, blew air through the ports that go through the firewall? Would that have runined my day?!?

Thanks in advance,

Stuart

 

Go back and retrace your steps. (as if you probably haven't already!) This is a vacuum problem. Did you disconnect or knock off one of the fittings under the hood? Maybe the check valve from the intake manifold to the dash or its related tubing. Did you do anything in the cab in the area around the control head? Under the panel where the vac lines all come into the head? Double check all your vacuum lines. Look & listen. How about the heater? Will it only blow out the defroster?

 

Wayne - Heater blows out of the defroster ports. I have a sinking feeling that I need to pull the dash off.

 

Nah, It's in failsafe mode. That's something the engineers build into the system in case of a complete vacuum loss in either winter or summer. Idea being that its more important to keep the windshield clear if anything goes kaput! Thats also why all the doors are vacuum operated except the blend door which is elec. When they lose vacuum the doors open/close respectively to blow all air to the defroster, hot or cold.
At any rate your problem is outside unless the vac harness under the dash is completely shot or missing or something. Not likely unless you have a big foot and a mean temper. Trace the vacuum line coming out of the right side of the intake manifold near the rear. (There are several connections in this same area). It goes into a check valve and then back to the firewall and in under the cowl vent. There it goes into the vac. storage box and then inside to the controls. The hose may be off, split, or missing at any point along the way. Or the storage box may be cracked (less likely but check it). You'll have to take the wipers off and remove the cowl screen to get to the box.
WC

 

Son of vacuum line. There was a tiny black vac line that came loose when I was removing the pressure lines!!!!!!! Slid it back on and wham - I got a/c. Thanks Wayne. I owe ya BIG time.

 

WHOO HOOOOO!
Glad ya found it! Yeah, those lines are quite small but effective (or not) as the case may be. Thanks for reporting back and good luck!
WC

 

How hard of a job would it be to install A/C intoa truck that doesn't have it?

 

Not impossible, but probably not worth the effort...alot of effort and cost. Components, brackets, wiring, etc. And for the most part you would want NEW components as opposed to junkyard stuff to be certain that when you were finished you didn't inherit any other problems. The worst part would be under the dash. The dash has to come out of the vehicle to do the work required, i.e. controls, wiring, vac lines and then of course the evaporator has to go into the HVAC unit. I'm not sure if there is a separate box for a/c and non-a/c vehicles, or if the mfg. just left out the evap.
I think you get the idea though. And it would really help if you knew something about a/c to begin with and these trucks systems in particular. If it were mine, I wouldn't do it. Just too much work.
WC