heater controls freaking out
 

ok heres the deal.

my 88 chevy pickups hvac controls will go crazy. everything will flash and the a/c will go on and off repeatedly and will get stuck on defroster. the only way to get it to stop is to pull the fuse, which leaves me without a heater or defroster. it used to be that if i leave the fuse out for a couple hours it would go back to normal and work fine, but now if i put the fuse back in it will just start freaking out again right away.

could this be the controls in the dash or could something else cause it to do this?

Re: heater controls freaking out
 

Not abnormal. Check out O'Reilly's Auto Parts (on line) and see how much they sell the control head for. They're available remanufactured.

Re: heater controls freaking out
 

thanks, ill look it up.

Re: heater controls freaking out
 

ok, so i went to the junkyard and grabbed 4 control units. i figured why not? ill have extra.

same problem.

i pulled the digital heater controls from my uncles pickup and changed the relays behind the glove box. i know all this stuff works.

same problem.

any other ideas?

Re: heater controls freaking out
 

Has anyone changed out the radio or added audio type equipment?

Re: heater controls freaking out
 

nope, truck is bone stock.

Re: heater controls freaking out
 

Mine was doing that and I replaced the control module and it fixed the problem. There was a TB out for the '92 trucks that said this was a common problem. One thing I also did was clean the connection ends on the wire to the controller.

Re: heater controls freaking out
 

by control module you mean the unit that is in the dash below the radio?

Re: heater controls freaking out
 

mine acts up when I switch on the running lights,or headlights.....
digital all dancing everwhere

Re: heater controls freaking out
 

Could be a grounding issue, or it could just be a symptom of the control unit taking a dump.