'89Lariat

Title says it all. I just replaced my HVAC blower motor, reconnected everything, and now my HVAC is stuck on defrost. I can hear a clicking sound which seems to be coming from under the hood when I move the selector lever. Whether it's a fluke or I screwed something up, any ideas of what could have happened? Tonight I will have a helper try to locate the source of the click while I move the lever, but if there's an obvious answer please let me know.

grilljames

Is it vacuum controlled or cable operated ?

dirtcrew51m

89 prolly cable, make sure all of the clamps for the cable are ok, and make sure the door is not binding and the cable is properly hooked up. The clicking might be the ac compressor engage\disengage, they do that also during heating.

'89Lariat

I think it's vacuum operated. That said, I don't know how to tell for sure.

grilljames

Usally vac controlled heater controls are easier to move the **** then cable operated. I have a 95 so im not 100% sure on that. If its cable then i agree with DIRTCREW, check to see if you gotta bind of some kind, and if it is cabel a little WD-40 or PB Blaster wont hurt to oil the cable a bit. When you run your defroster or floor/defrost your a/c pump will kick in and out to help dry and moisture on the inside of your windshield provided your a/c works which if the clicking sound you hear is the ac pump then ur ac does work. Next time pop the hood and see if the ac pump is kickin on and off as you hear the clicking.

'89Lariat

Okay, it is for sure vacuum controlled, and it has sliders instead of *****. I think it has cables going to vacuum solenoids, then the vacuum tubes go through the firewall. Anyway, I found the problem, I had a seemingly unrelated vacuum hose that was hanging loose, I reconnected it and everything works.

grilljames

Good deal, thx for posting what fixed you issue for the next guy.

ridge903

At the same time for some FYI i was under the impression the only reason the ac compressor kicks on when you have the heat on is to keep the ac compressor internals lubercated instead of sitting all winter and then summer come around an you issues cause my ac dont kick and my heat keeps my winds clean just fine

'89Lariat

In a properly functioning system, the AC acts as a dehumidifier. If you ever have a very long cold winter without a properly functioning system, you'll notice that humidity starts to build up inside the cab from your breath, or from water on your boots, etc, to the point that it freezes on the inside of the windshield. Heating it will still defog the windshield eventually because you are raising the dew point, but it won't get rid of any excess humidity.

I believe it only comes on when you are in defrost/defog mode.