when i turn the ignition to on, the blower motor comes on full blast, nothing i do on the hvac controls has any response, no matter if i slide it over to off or mess with the fan speed dial. this just starting happening the other day. what could be causing this?

 

High speed relay under the hood bad ?

 

do you know how to test it?

 

The schematic on the top of it.

 

ok thanks

 

could a bad resistor be the cause too?

 

Check vac line in engine compartment if blend doors aren't moving.
Electrical is a easy fix with FSM wiring diagram.

 

THe resistor isn’t used on high

 

ok good to know.

 

What Tuned said about the resistor.

For high speed, the relay "replaces" the feed to the blower motor that has been through whichever resistor(s) to set the speed, with a hard battery feed. The switch on the dash sends power to its coil when in the High position to make it changeover.

Sounds to me like either the relay has melted permanently into the high speed position, or the usual connectors have burned up, and someone alternate-ethnically-engineered something to give them at least SOME blower function.

There is a connector in the battery feed to that relay that often burns up. I would say ALWAYS burns up, except that there MIGHT be one out there somewhere that hasn't burned up yet, which would make a liar out of me. You can find it easily enough: start at the relay, look for the big fat red wire, follow it over toward the driver's side; right about at the pass side valve cover you'll come across the absolute worst stooooopidest most pathetic design connector EVAH. It must be replaced with something that can handle HIGH current (40A would be a good target); NOT the usual little weenie slide terminals that you see, for example. There's another of these same idiotic boneheaded connectors in the dash, feeding power to the control head, which is probably the one that made somebody RIG the car like it probably is. If you pull the control head and look at its harness, you'll find the fan speed switch, and the "mode" switch; look at the "mode" switch, you'll find 3 wires, 1 is green and goes to the compressor, 1 goes to the fan switch, and 1 is brown and goes up into the dash. Follow the brown one and in about a foot or so you'll some to another of those pitiful moron connectors. Replace it as well.

Do a search on these forums for my userID and the phrase "burnt to ashes", you'll find pictures, other people's accounts of finding and fixing it, etc.

 

thanks man for the info, yea everything was working fine for the 10 years ive had the car, but the other day yea just started acting like that. i havent been driving it for the last 5 months because i have it torn apart to do new carpeting and stuff and a new paint job. ive just been running it here and there.

 

finally got around to buying a new relay, it was indeed the problem, thanks for pointing me in the right direction!