92 lumina apv-a/c heater control-speedo

03-25-2007, 02:59 PM
[signtext]Boy do I need help with this! Everything was working fine. Took a 10 mile drive, a/c worked and speedometer working. After getting in to drive home, went crazy. Fan blows only on floor, cant turn fan off using off button, but can change speeds, no cold air, light indicating fan speed doesnt work, and the speedo never moved off zero. And the cruise didnt work either. After getting home, saw the ignition fuse was blown. Put in a new one, started her up and the new fuse started to melt! 15 amp like it should be, got very hot and soft. Before I noticed the fuse heating up, turned on a/c, started blowing out of the vents,and the little fan speed light came back on, but no cold air. Didnt drive it so dont know about speedo and cruise.Everything else seemed to work.Sounds like more than one problem to me.What does this fuse control? It started and drove with it blown. Is the a/c compressor gone? HELP!!3.1 auto
I am back with new info Tried new fuse, ok, tried heater fan, ok, tried a/c, ok, but not cold, compressor did not engage. Wiggled connection to compressor, tried again, now cold, compressor engaged, fuse ok. Am still concerned with the hot fuse I had. Also the connection seemed fine. Will pull it off and try to clean. Any ideas out there? Am pretty good with physical things that can be seen but electrical loses me. Nick in SC

03-25-2007, 05:47 PM
As a starter, here is the heater diagram:
A lot of components are served by this 15A fuse and the elements you have seen as dead were all victims of same cause, at this time, unknown; each of them can be the culprit in blowing the fuse. But "cant turn fan off using off button," would make me investigate low speed heater relay, in the convenience center.

One question of interest: were you able to run the HIGH blower speed? While there are several circuits tieed to this 15A fuse, most are only relay coils; the only significant load is the blower motor on lower 3 speeds. THe high speed takes only relay coil current and the HIGH current is taken direct from the battery through the high speed relay..unless a failure mode in the HIGH speed relay would allow the switch to deliver the current to the motor through the 15A fuse...which cannot take the 25Amps required by fan motor at high speed. THis is just hypothesis...but strange failures modes for the high sped relay have been reported. If you use the hihger fan speed for long periods of time, expect HS relay or fan motor failure down the line.

03-25-2007, 11:24 PM
Thanks for the reply. Drove around some tonight, only problem sometimes cold air, sometimes not. Fan did and does blow on all speeds. Is there a relay between the push button and the compressor? Of course there must be, could you show me where it is? Is it in the convenience center and where is that? Behind glove box?

03-26-2007, 12:02 PM
yes convenience center is below glove box.
THis is compressor control circuit
This is a low poser circuit..only the relay is connected to this fuse circuit. The clutch circuit is independant.
I'm not sure exactly what you mean by "no cold air" : do you mean the compressor does not run or the heater temperature control does not work properly? Compressor relay is here:
By the way, a/c compressor failure by itself would not blow the fuse, so I would not insist in that direction. Low pressure (loss of refrigerant or simply low outside temperature) will prevent clutch from engaging.

03-26-2007, 01:33 PM
I had a problem almost similar to yours. My vents would not switch from floor to vent or to anywhere and my cruise control did not work. It was a vacuum line that sits behind the throttle body that rotted out. The vent position is controlled by vacuum, (it is on my van anyways). I followed the line to the back of the throttle body and found where it had fallen off and slipped it back on. Haven't had a problem with it since.

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