A/C / Defrost blower not blowing.

[rashwor]

All,



I drove my '05 to the store and took care of an errand. Came out and fired it up and the A/C blower is not blowing on any position (low, 2, 3, or purge). I can move the air direction / vent selection control to any position and no air blows out of any of the vents. The light indicating the the A/C compressor is allowed to run is on and the A/C compressor is cycling on and off as it should. When driving down the street on the way back to work, there is a small amount of cool air coming out the vents with highway speeds and it is cooler than outside air.



What gives and where to start?

 

[B.G. Smith]

Can you hear the blower motor running? Sounds like the motor may have failed. bg

 

[rashwor]

No, the blower motor makes no noise and is not running.

 

[B.G. Smith]

Look behind the glove box and you can see the resistor block for the fan motor, it is held in place by a screw and has several wires running to it. The resistor plugs into a receptacle, the contacts in the plug could be corroded, even if the resistor is bad the fan should still run on high setting. If resistor is ok then the motor has probably failed, I believe you can replace the blower motor from inside the cab without removing a lot of equipment. Might have to remove the glove box insert. bg

 

[rashwor]

Thanks BG. I am going to try to get to the wire harness that plugs into blower motor when I get home and check it with a test light. If I get juice to the motor, then the motor is bad.



My hunch is the control unit in the dash is bad. Reason: The amber light indicating that the A/C compressor is in use stays on irregardless of pushing the button to turn it off or turning the blower control switch to the off position. Previously, the pushbutton would turn the amber light and the A/C compressor off just as the off position would on the A/C speed control dial.



I will update as I know more. Please chime in if you have additional thoughts.

 

[rashwor]

Update. It appears that Gremlins have moved in. I got in the truck to drive to the auto parts store to see what was available aftermarket. Cranked the truck and the A/C starts blowing cold air! I proceeded to the parts store and found that all of the electronics except for the control unit in the dash is available aftermarket as I expected. Cranked the truck to go back to work and the A/C proceeded to blow cold air on the return trip.



It will quit working again and I will do some testing to see what I can figure out. In the mean time, I am going to be happy that it is blowing cold air! I hate Gremlins, especially electric ones!

 

[B.G. Smith]

Yeah, I don't understand the light staying on??? The problem being intermitten is gonna make it hard to find. May just be a bad connection somewhere/ bg

 

[SWithrow]

My truck did the same thing a few years ago, turned out to be the igntion switch.

 

[rashwor]

It all worked as it should yesterday on the way home and this morning on the way back to work. I hate trying to track this kind of thing down. If / when it rears its head again, I will do some testing to make sure it is not the blower motor and then probably swap the ignition and / or A/C control in the dash. If I can find someone that I trust to do diagnostic troubleshooting, that would be the best way to go but I am pretty picky and most local techs don't care very much.



BG, the light staying on is what made me think it might be the A/C control unit in the dash... that simply should not happen as long as the control is working correctly.



SWithrow, thought about that briefly... makes since since as according to the service manual it is part of what completes the circuit and technically anything involved in completing the circuit could be the problem.



I appreciate everyone's thoughts and help. If you have any more, don't hesitate to share. I will keep everyone updated as things happen.

 

[SWithrow]

Had returned to my truck a couple of times only to have the blower motor running, come to find out that the tilt was causing stress on the ignition wires pulling on the connector and plug. It burnt the plug and switch so bad that I had to replace both. Now I opt out of using my tilt.

 

[TLane]

I've seen this happen on other vehicles where the brushes in the fan motor were worn. The brushes reach the end of travel and make poor connection to the armature. One day it works, the next it doesn't. Try tapping on the motor next time it doesn't work and see if it comes on. Also, if you can, connect a test light to the two wires going to the motor, you'll be prepared next time it doesn't work. You'll be able to see if power is going to the motor or not, this should give you a better clue as to where the problem is.

 

[rashwor]

The issue returned today at lunch. Once again, later this afternoon it worked fine. We will see how it does on the way home. I will have to do some investigating this weekend looks like.



Any suggestion on how to pop the clips loose on the dash trim in case I need to get into the center dash? Service manual says to use trim tool C-4755 or similar to pop them loose. I have no idea what the tool looks like or the clips look like and I don't want to break the clips.

 

[SWithrow]

Try to tilt the steering wheel up and down and see if the blower comes on... just a thought


I can't say how the 05's are but no special tools to remove the center on a 03. Just one screw where the hook is on the dash.

 

[rashwor]

I will try the tilt the next time it quits. I almost never move the tilt steering as I am the only one that drives the truck, but it is still worth a shot.



SWithrow, it sounds like you have had your center out from your previous reply. If you have, how did you get the retainer clips to release after you took the one screw out?



Thanks for all the help and input everyone.

 

[SWithrow]

SWithrow, it sounds like you have had your center out from your previous reply. If you have, how did you get the retainer clips to release after you took the one screw out?

Grab the hook and give a slight tug, I'm not positive on yours so be careful, once it pulls free at the hook just work your hand around and the rest should pop free

 

[rashwor]

Update. Well, I tested the tilt steering wheel theory Friday afternoon on the way home from work. It had no effect. I got the blower speed control unit changed out of the center console Saturday afternoon. SWithrow, the center console popped out just like you said it would. It took less than 15 minutes to change out start to finish.



Did not get a chance to test it to see if that solves the problem. I was going to, but I opened the hood to check the oil and give a quick once over. Once over revealed the water pump is out. Crude! Hope to get that fixed today and be back in the truck Tuesday.



On the up side, it was time to change the coolant again anyway... this will get that little chore done!

 

[rashwor]

Update again: I got the water pump thermostat swapped Monday and that cured my water leak. To my surprise, the pump did not have any slack in the shaft (side to side or in and out); it was only leaking with a bad seal.



Since then, I have been driving the truck and the A/C blower has been working as it should. The last couple of days have been in the 90* range where I was having the problem with the old control so it seems to indicate that the problem is fixed.



Thanks to everyone for the help, advice, and pointers.

 

[rashwor]

Electrical Grimlins... . The blower had a spell this last week so I am still hunting. I will keep you updated. I am hoping it is not the ignition switch. What is involved in changing the ignition switch so that it and the driver door are keyed to match each other?

 

[rashwor]

SWithrow it sounds like you change your ignition switch. I have decided that my problem is the ignition switch. I am looking for guidance from someone who has changed the switch before. I have looked at the service manual for the process and it is kind of lengthy and a bit intimmidating to me. I have a couple of questions about the process:



1) Do I need to remove the lock cylinder as stated in the service manual? I know the lock cylinder and ignition switch connect, but does the cylinder lock need to come out?



2) Is disconnecting the negative battery cables sufficient to prevent accidental airbag deployment? In the service manual, it says that you need to actually open up the steering wheel and disconnect the electronic control of the airbag in there.

 

[SWithrow]

I don't recall taking out the cylinder just the screws holding the switch and as for removing just the negative that is all I did.