dash vents not working

telemaster

Original poster
Member
Jan 1, 2013
4
hi everyone . joined the site today and could use some help. the dash vevts on my 2002 trail blazer wont work after installed a new battery last year. defrost, floor and rear vents work fine. also cant listen to radio with motor not running even for a few minutes or battery will go dead. any ideas. sure could use some help
 

Matt

Member
Dec 2, 2011
4,009
telemaster said:
hi everyone . joined the site today and could use some help. the dash vevts on my 2002 trail blazer wont work after installed a new battery last year. defrost, floor and rear vents work fine. also cant listen to radio with motor not running even for a few minutes or battery will go dead. any ideas. sure could use some help

Sounds like the actuator for the vents has had the dick. You could pull the fuse and see if it resets it...but if it doesn't. it'll need to be replaced.

Can't really help with the radio, the only thing that comes to mind is the RAP feature that will allow everything to work for 15 minutes and then shut off automatically unless you have the key turned to ACC.
 

telemaster

Original poster
Member
Jan 1, 2013
4
I guess i should have been a little more specific about the battery going dead. it doesnt matter what is turned on, within 5 minutes or so the battery will go dead. I had to hooh up the battery charger to try to recalibrate the hvac actuators. Which, by the way did not sove the problem. Big suprise huh ? is there an easy way to tell which actuator is bad with out opening up the dash ? I sure hope some one has an answer for these problems . These newer cars boggle my mind. Also the t/b is a 2003. Sorry my typing is not very good.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
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In case you haven't heard:
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If the battery goes dead after only a few minutes, IMHO, either the battery is bad, the alternator is bad or both. There could also be a problem with one of the battery connections.
If the battery is that low on power, it could mess up the HVAC actuators every time.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
A battery that discharges that fast is a serious safety issue. Either the battery has gone bad after replacement, or there is a HORRIBLE current drain. If you had a bad actuator that could drain a battery within minutes, it would certainly blow a fuse.

The amount of energy that must be draining would be (I guess) in the 300-500 Watt range. Something's gonna heat up and lead you to it by the burning wiring if nothing else.

Do you have a voltmeter and some experience using it?

We need more details. Does the battery discharge when you have the ignition switch off and the key out? If the answer to that is no, what mode do you have the switch in to cause the discharge?

There are five actuators, and they are trivial to troubleshoot functionally. Driver's side temp, passenger's side temp, dash/feet airflow mode, defrost airflow mode, recirculate airflow mode. Whatever function doesn't work is the bad one.

But you have much more serious problems to deal with first.

Any other observations you haven't shared yet? We *do* have the best team of volunteer troubleshooters around. Trailvoy is a ghost town by comparison since we ALL left. I bet you just heard that phrase over there. :wink:
 

telemaster

Original poster
Member
Jan 1, 2013
4
Hi Roadie. thanks for your reply. I need help. Let me try to answer your question. Yes I do have a multimeter & can use it fairly well. Battery drain only occucrs with ignition switch in acc or engine run but have not started motor. Like if wife was listening to radio at lunch break. No hot wires or smoke. Have had this problem since last fall when a change the battery. Since then dash vents dont blow and have battery drain. Wife still drives car every day with no problem as long as she does not use batt pwr to listen to radio at lunch or forget & leave some lights on. if she does then batt is dead in a few minutes. otherwise can drive it normally with no problem. Alt charges batt at 14v. Hope you have some ideas , I am stumped. Also can you tell me how to find out which actuator operates the dash vents. Mabe this bad actuator is causing the drain as you said ? thankyou for helping me !
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
telemaster said:
Have had this problem since last fall when a change the battery.
See why we're suspicious of the battery? Recommend you charge the battery, get a good 12.6-12.7V on it, then put the voltmeter on it with the ignition off for a while. Write down the voltage every minute. Then turn the ignition on and do the same thing. Then put in another battery with jumper cables (removing the old one's connection) and run the same test as before, with another battery for comparison.
Also can you tell me how to find out which actuator operates the dash vents.
I posted which one. The one that selects dash/feet airflow mode.
Mabe this bad actuator is causing the drain as you said ?
No actuator could draw enough current to kill a good battery without blowing its fuse.

allactuators-orig.jpg
 

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