Battery dead overnight .. A/C cabin fan on when car is parked/off

[dsbrad1]

Hopefully someone can help me.

Sometimes when I go to start my 1996 Saturn SL1 (manual) in the morning, the battery is dead. I've had it tested and it has been called good. Every once in a while, I'll go outside and the A/C cabin fan is blowing air into the cabin when the car is off and parked.

The fan switch is in the off position. but when it does come on, it blows at max.

If I turn the ingnition switch to ACC then off, the fan will turn off... but will start blowing again later on. Sometimes the fan will turn off by itself.

Could this fan be draining my battery? If so, where would I start to find out if this is what my problem is? If not, are there any insights? Clues? Hints?

Thanks for the help in advance.

[OldNuc]

Yes, if the fan runs all night the battery will be dead, dead, dead. There is a blower relay in the I/P junction box next to your foot when you are driving that just might be sticking in the FAN ON A/C position. It is labeled HVAC BLOWER. The FAN ON A/C position bypasses the 5 speed fan switch.

[madpogue]

Originally Posted by OldNuc

There is a blower relay in the I/P junction box next to your foot when you are driving that just might be sticking in the FAN ON A/C position. It is labeled HVAC BLOWER.

No, there isn't. Power goes right from the RUN position of the ignition switch to the fan switch.

The FAN ON A/C position bypasses the 5 speed fan switch.

No, it doesn't. When you turn the A/C on, it doesn't automatically turn the fan on.

If your car were a later model, I would suspect that it was programmed for "afterblow" (runs the blower briefly after shutting down), but your '96 doesn't have that feature. If it's going on even with the fan switch off, there has to be a short somewhere, right to the blower motor.

[fdryer]

Just throwing this out there for general comment on the OP's dilemma; if the (original resin-tipped) coolant sensor were shorted internally as opposed to having the high resistance associated with it, would the short be interpreted by the PCM as an overheated engine, subsequently turning on the fan? It fits in with hot engines that still have fans blowing after the engine's shut down until the coolant temps drop where the fans shut off. In this case the coolant sensor just needs to be replaced ASAP to stop the runaway cooling fan from killing the battery. Just my 2-cents.

[OldNuc]

The OP states that it is the cabin fan, not the radiator fan. But, if he has not sacrificed the resin tipped ECTS yet to the Saturn gods he should put that on his To-Do list also.

Sticking relay is a good place to start.

[OldNuc]

Originally Posted by madpogue

No, there isn't. Power goes right from the RUN position of the ignition switch to the fan switch.
No, it doesn't. When you turn the A/C on, it doesn't automatically turn the fan on.

If your car were a later model, I would suspect that it was programmed for "afterblow" (runs the blower briefly after shutting down), but your '96 doesn't have that feature. If it's going on even with the fan switch off, there has to be a short somewhere, right to the blower motor.

Ture, it was early, gimme a break... It is still most likely sticking in the high position as that will bypass the switched power. Highest speed is direct from IGN-3 which is not switched. Suspect the vibration of the OP climbing in the car and closing the door jars the relay enough to turn it back off. either that or hitting the kick panel with a foot. He also stated that it always was on the high speed. This is the CABIN fan not the radiator fan that is causing the grief.

[madpogue]

Reviewing the wiring diagram, it looks like it's POSSIBLE that a sticking A/C relay can cause a sneak circuit to the cabin blower. Fortunately, that's easy enough to test -- next time it happens, pull the A/C relay.

But that's the A/C relay under the hood. There is no relay for the blower itself.

[OldNuc]

Look at the HVAC BLOWER relay for the Cabin fan. That is the one that makes the fan inside run. If you turn on the A/C and switch to the highest speed and it sticks then the fan will gleefully run till the battery succumbs to exhaustion.

If you selected a lower setting when this problem were occurring and the fan speed decreased then your sneak circuit would be the problem. the OP did not mention anything about changing speed, just cycling the key. The key cycle is the major point of question here in my mind. But whacking a relay to start is easy for the electrically challenged who do not have the wiring diagram available.

[madpogue]

Originally Posted by OldNuc

Look at the HVAC BLOWER relay for the Cabin fan.

There still isn't one.

[OldNuc]

Well, this is from a Gen 2 schematic / location diagram and it sure insists that there is one.

I have to go up north shortly and will pull the panel and verify the drawing. I do not have one for a 96 vintage but this is for a 98/99 vintage, both are Gen-2 and should be real close.

[madpogue]

There isn't one in either my '96 FSM diagram or my '96 car.

[dsbrad1]

Guys, thanks for the replies and giving me a place to start. It's much appreciated.

I'm going to take your advice and see what I can find over the next few days.

And to clarify, it is the cabin fan, not the radiator fan.

I had thought of pulling the AC fan relay under the hood. Perhaps I'll start there as that's the easiest to check..

Thanks again everyone. I'll let you know what happens.

[fdryer]

Uh, unless you're mistaken but certain that the interior cabin fan is the occasional runaway, I am mistaken about the radiator fan being the problem. The radiator fan needs a relay to switch it on or off. The interior blower, for heat and ventilation, has a four position switch that selects from a resistor card the two speeds (low, medium) and a direct connection for high speed. This circuit would be the area to examine for any short allowing the blower to run uncontrolled.

[OldNuc]

Originally Posted by madpogue

There isn't one in either my '96 FSM diagram or my '96 car.

Well thats strange, I checked the application on a well known parts site and they think there is one. Obviously, they are not correct. I suspect that you can spot a relay in a panel.

I wonder when Saturn decided that there was a need for a relay.

[madpogue]

Originally Posted by dsbrad1

I had thought of pulling the AC fan relay under the hood.

There (STILL) isn't one. There's an A/C relay, but that's for the A/C compressor, not the HVAC blower (the blower isn't [just] an "A/C fan"; it's primarily there for the heater). Then there's the FAN relay, which is for the cooling (radiator) fan.

Originally Posted by OldNuc

I wonder when Saturn decided that there was a need for a relay.

Maybe when one too many cars came in with dead batteries from the HVAC blower running all night....

[OldNuc]

Originally Posted by madpogue

There (STILL) isn't one. There's an A/C relay, but that's for the A/C compressor, not the HVAC blower (the blower isn't [just] an "A/C fan"; it's primarily there for the heater). Then there's the FAN relay, which is for the cooling (radiator) fan.

Maybe when one too many cars came in with dead batteries from the HVAC blower running all night....

If there is no relay then I would have to guess the Prince of Darkness is at work again. The OP mentioned that cycling the key turned it off.

My experience is that if you posses a functional spare for any installed automotive component that component will never fail. I am shopping for a new ignition switch and lock cylinder.

[BarnOwl]

Originally Posted by OldNuc

My experience is that if you posses a functional spare for any installed automotive component that component will never fail. I am shopping for a new ignition switch and lock cylinder.

Oh I dunno about that. The CPS went out on my wife's car and I pulled the one off that engine I used to have laying around with the cracked head. It worked fine. However, it's nice to know that my starters, alternators, power steering pumps, drive axles, wiper modules, and all sensors except the CPS are bullet proof now.

[dsbrad1]

Originally Posted by fdryer

Uh, unless you're mistaken but certain that the interior cabin fan is the occasional runaway, I am mistaken about the radiator fan being the problem. The radiator fan needs a relay to switch it on or off.

It is the interior cabin fan that is the runaway. It came on last night and I made sure that just the interior fan was running and not the radiator fan.

Originally Posted by fdryer

The interior blower, for heat and ventilation, has a four position switch that selects from a resistor card the two speeds (low, medium) and a direct connection for high speed. This circuit would be the area to examine for any short allowing the blower to run uncontrolled.

Where would I find this circuit? Since the fan only comes on at high speed, it's safe to assume that the resistor card is okay. It's the direct connection that I'm looking for.. I've been looking for a wiring diagram and not having any luck.

[dsbrad1]

Originally Posted by madpogue

There (STILL) isn't one. There's an A/C relay, but that's for the A/C compressor, not the HVAC blower (the blower isn't [just] an "A/C fan"; it's primarily there for the heater). Then there's the FAN relay, which is for the cooling (radiator) fan.

You're right, there is only the A/C relay. A poor choice of words on my part.

[madpogue]

Originally Posted by OldNuc

If there is no relay then I would have to guess the Prince of Darkness is at work again. The OP mentioned that cycling the key turned it off.

But His Dark Highness would have to be working in cahoots with something else; even if all the contacts on the ignition switch shorted, if the blower switch is set to OFF, it shouldn't go on. There's gotta be something somehow sending power PAST the blower switch, right to the fan motor.

My experience is that if you posses a functional spare for any installed automotive component that component will never fail.

Sounds like another of the "Laws of British Sports Cars" (check that gulp valve!).