Sorry if this has been asked before.

I recently purchased a 1998 base model 3.1L Malibu. I'm very happy with it except for one nagging inconvenience.

It's HOT up here in MN right now, thus I've been using my A/C a lot lately. The problem is that when I first start the car, the airflow setting always defaults to external. With 100+ degree weather, the A/C can't keep up so I always have to try to remember to switch to re-circulate (internal air). This setting will also change sometimes when I change the fan speed and I have to change it back.

My questions are:

1) Is this some kind of feature?

2) I'm an Electrical Engineer so I can easily build a 555 circuit to force the setting to re-circulate upon start-up while leaving the option to switch to external air intact (for winter defrost). Can anyone think of a reason that this would be a bad idea from a mechanical perspective?

Thanks for any responses.

Sorry if this has been asked before.

Can anyone think of a reason that this would be a bad idea from a mechanical perspective?

Thanks for any responses.

Welcome to the forum. Hope you stick around and help some others out whenever you can.

This subject has been discussed a LOT in the last few weeks.
Please do us the courtesy of looking around just a LITTLE bit before asking your first question.

Yes, it appears that it is a feature and with good reason.

After your car sits out in the sun, the temp inside can get above 140 F.
The outside temperature, however, is only 95 (or example).
So cooling the outside air is easier than cooling the recirculated inside air........for the first few minutes. It also helps to crack a back window or sun roof just a tad for a few minutes too to help exhaust that super-heated air, before you switch it over to recirc.

I cannot take credit for figuring this out; another forum member pointed it out to us.

Not sure why the fresh/recirc changes when you change fan speed. That could indicate some sort of system glitch, or it could be the BCM's programming but I doubt that.

If you've ever tinkered with temp sensors you could place one outside and one inside and have your 555 use the input from both, choosing the lower one then the setting is on AC, and the higher one when the setting is on heat. That way you'll get the kind of air input to the system you want, depending on air temps (did you just recently run the car?) and season (summer/winter). Detecting the setting could be from the mode control or temp position or storing the last setting of the fresh/recirc button.

Sorry if this has been asked before.

I recently purchased a 1998 base model 3.1L Malibu. I'm very happy with it except for one nagging inconvenience.

It's HOT up here in MN right now, thus I've been using my A/C a lot lately. The problem is that when I first start the car, the airflow setting always defaults to external. With 100+ degree weather, the A/C can't keep up so I always have to try to remember to switch to re-circulate (internal air). This setting will also change sometimes when I change the fan speed and I have to change it back.

My questions are:

1) Is this some kind of feature?

2) I'm an Electrical Engineer so I can easily build a 555 circuit to force the setting to re-circulate upon start-up while leaving the option to switch to external air intact (for winter defrost). Can anyone think of a reason that this would be a bad idea from a mechanical perspective?

Thanks for any responses.

You have two things going on.

First, as MalibuKen points out, that's a feature - consider carefully that any A/C unit is just a heat pump and can only pump so much thermal energy. Would you rather it cool 95F air, or 140F air, if it can only cool it 50F?

As to the "fan speed causes it to kick off", there's a link I've posted to the problem with the Gen5 A/C head units - as an EE, it should be easy to handle taking it (or what I recommend, another one from a Pick/n/Pull or U-Pull-It type yard) and fixing it right.

http://www.imcool.com/articles/aircondition/AC_ControllersAreRepairable.pdf is a PDF from an article written in 1998 or 1999 about this very problem.

What happens is you're jarring the temp control just enough for it to drop A/C and bring it back. It does NOT get any better, and as far as anyone I've talked to can tell, GM never fixed the design - so we get to fix it later.

Read that PDF, buy another head unit, fix the other one, swap out, and you should be good to go.

I'll add that while you've got it open, not a bad idea to replace the grain-of-wheat type lamps so that you don't lose illumination (I have one good bulb in mine, since they're soldered in. Gotta fix a spare one and swap. AGAIN.)

RwP