Air temperature oscillating from blower...
#1
02-17-2011, 02:38 PM
Air temperature oscillating from blower...
EDIT:
Skip ahead to post 13 for the solution. I suggest reading posts 13 through the end, and then THIS edit, before repairing the module.
(the 'FIX' described in this thread, for the common cracked gear - see pics, is working perfectly. BUT, BEFORE YOU DIS-ASSEMBLE THE MODULE, NOTE THE POSITION OF THE METAL STOP ON THE SHAFT pic post 16. And when you remove the shaft with the cracked gear, NOTE THE POSITION OF THE BLUE GEAR - DO NOT LET IT TURN; IT AFFECTS CALIBRATION AFTER RE-INSTALLATION.
The nylon washers are not necessary, but they will strengthen the gear from further breakage. If you glue them onto the gear, they WILL increase the working width of the gear on the shaft. I said somewhere that it appeared that the working width doesn't matter. It does, sort of. You'll have binding when you screw down the case. I solved this by Dremeling the interior surfaces of the case, to accommodate the increased width. )
USE CAUTION - THE GEAR IS PROBABLY BRITTLE AFTER SO MUCH EXPOSURE TO HEAT. I had mine fixed, and made the mistake of re-opening it, and cleaning it up. I broke the fixed gear COMPLETELY into 2 pieces, and had a SERIOUS job cleaning up the superglue, and RE-REPAIRING the assembly. It worked - AGAIN.
The MOST important thing, as noted elsewhere, is to NOT worry about the gap from the crack - if you follow directions on re-installing it onto the shaft, it does NOT mesh with the blue calibrating gear. AND, if you try to close that gap when you have the gear off of the shaft, YOU WILL NOT GET THE GEAR BACK ON THE SHAFT. Slippage of the gear is NOT a concern either.
================================================== ================================================== =============
... hot, then cold, then hot, and I can hear MAYBE the duct door spinning like a top back and forth.
I have FSM, but it is nowhere near as good as other GM FSM's...
Any ideas here on duct door control?
Skip ahead to post 13 for the solution. I suggest reading posts 13 through the end, and then THIS edit, before repairing the module.
(the 'FIX' described in this thread, for the common cracked gear - see pics, is working perfectly. BUT, BEFORE YOU DIS-ASSEMBLE THE MODULE, NOTE THE POSITION OF THE METAL STOP ON THE SHAFT pic post 16. And when you remove the shaft with the cracked gear, NOTE THE POSITION OF THE BLUE GEAR - DO NOT LET IT TURN; IT AFFECTS CALIBRATION AFTER RE-INSTALLATION.
The nylon washers are not necessary, but they will strengthen the gear from further breakage. If you glue them onto the gear, they WILL increase the working width of the gear on the shaft. I said somewhere that it appeared that the working width doesn't matter. It does, sort of. You'll have binding when you screw down the case. I solved this by Dremeling the interior surfaces of the case, to accommodate the increased width. )
USE CAUTION - THE GEAR IS PROBABLY BRITTLE AFTER SO MUCH EXPOSURE TO HEAT. I had mine fixed, and made the mistake of re-opening it, and cleaning it up. I broke the fixed gear COMPLETELY into 2 pieces, and had a SERIOUS job cleaning up the superglue, and RE-REPAIRING the assembly. It worked - AGAIN.
The MOST important thing, as noted elsewhere, is to NOT worry about the gap from the crack - if you follow directions on re-installing it onto the shaft, it does NOT mesh with the blue calibrating gear. AND, if you try to close that gap when you have the gear off of the shaft, YOU WILL NOT GET THE GEAR BACK ON THE SHAFT. Slippage of the gear is NOT a concern either.
================================================== ================================================== =============
... hot, then cold, then hot, and I can hear MAYBE the duct door spinning like a top back and forth.
I have FSM, but it is nowhere near as good as other GM FSM's...
Any ideas here on duct door control?
Last edited by Schrade; 02-24-2011 at 06:30 PM.
#3
02-18-2011, 06:53 AM
What are you working on here? Year, make, model, auto or manual climate control, etc?
The 2nd gens have an electronic temperature door and oscillation typically means that the actuator is broken inside, more specifically, a gear inside the actuator.
The 2nd gens have an electronic temperature door and oscillation typically means that the actuator is broken inside, more specifically, a gear inside the actuator.
#6
02-18-2011, 12:47 PM
Now I'm digging further. I turned off the motor, and turned the key back to 'ON', motor OFF, and the mechanism is STILL going back and forth - about every 5-10 seconds - perfectly timed.
Does this tell me for sure 'Broken gear'?
Looks like I might have a broken gear ...
'98 Heater blend door groan/squeek cycling hot cold hot cold
Perhaps I can be of some help here; it seems many have had this problem, but nobody took the time to post their results.
Wife complained about the groaning/squeeking heater for some time. Dead battery caused my blend door to cycle constantly between hot & cold. This is what the computer is supposed to do (once) to learn where full hot & full cold is. Computer showed codes B0408, B0415, & B0416. Mitchell repair info has you checking all the circuits, then replacing the actuator with a "known good unit"($). If that isn't the solution, then replace the heater control module($!).
I decided to take out the actuator to take a look at it. Turns out it's not that hard to get out. The bolt in the back is not a bolt, only a pin. Thank God. The 2 front bolts are accessible with a 5.5 mm box end ign wrench after getting the vacuum pod out of the way. It takes some tedius wrenching, but it's better than removing the dash as others have suggested here. After getting it out, I took it apart to see if I had the famous "split gear problem". Sure enough the big gear was split & rubbing on the case, this was causing the groan/squeek problems. I checked the door movement & it was free & quiet. After replacing the actuator both problems were solved. So if your blend door is groaning, be prepared to change your actuator soon, because if you loose battery power, your computer will not be able to calibrate the door. Also the aftermarket actuators seem to be incorrect if you have climate control.
I tried to post this in the How-To thread, but I was not authorized. I've gotten some good information from this fourm & hope this helps someone else.
Perhaps I can be of some help here; it seems many have had this problem, but nobody took the time to post their results.
Wife complained about the groaning/squeeking heater for some time. Dead battery caused my blend door to cycle constantly between hot & cold. This is what the computer is supposed to do (once) to learn where full hot & full cold is. Computer showed codes B0408, B0415, & B0416. Mitchell repair info has you checking all the circuits, then replacing the actuator with a "known good unit"($). If that isn't the solution, then replace the heater control module($!).
I decided to take out the actuator to take a look at it. Turns out it's not that hard to get out. The bolt in the back is not a bolt, only a pin. Thank God. The 2 front bolts are accessible with a 5.5 mm box end ign wrench after getting the vacuum pod out of the way. It takes some tedius wrenching, but it's better than removing the dash as others have suggested here. After getting it out, I took it apart to see if I had the famous "split gear problem". Sure enough the big gear was split & rubbing on the case, this was causing the groan/squeek problems. I checked the door movement & it was free & quiet. After replacing the actuator both problems were solved. So if your blend door is groaning, be prepared to change your actuator soon, because if you loose battery power, your computer will not be able to calibrate the door. Also the aftermarket actuators seem to be incorrect if you have climate control.
I tried to post this in the How-To thread, but I was not authorized. I've gotten some good information from this fourm & hope this helps someone else.
Last edited by swartlkk; 02-18-2011 at 01:37 PM. Reason: *Combining Consecutive Posts* - Please use the EDIT feature to add additional information to your post if another member yet to respond.
#10
02-18-2011, 03:47 PM
Ok - I found the DIY tech link:
https://blazerforum.com/forum/tech-articles-diy-29/how-2nd-gen-blend-door-actuator-replacement-29981/
HOW-TO: 2nd Gen Temp Door Actuator Replacement
I hope there's a little more than this on the boards, because that is really no help at all...
I got my camera goin', so maybe I can get a little more to contribute here (got a few stickies in the vette forums
).
Is there any other threads on this actuator removal?
Do I need to pull the dash?
https://blazerforum.com/forum/tech-articles-diy-29/how-2nd-gen-blend-door-actuator-replacement-29981/
HOW-TO: 2nd Gen Temp Door Actuator Replacement
I hope there's a little more than this on the boards, because that is really no help at all...
I got my camera goin', so maybe I can get a little more to contribute here (got a few stickies in the vette forums
).Is there any other threads on this actuator removal?
Do I need to pull the dash?