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Chris_W
Chris_W 2/10/2014
2001 Chevrolet Silverado 1500 LT 8Cyl5.3L - Body & Interior
HVAC air flow problems...
01 Silverado LT, 5.3L, 4WD, $150k miles.
HVAC blower only turns on at setting 5; no blower action at all on settings 1-4. At #5, very limited air flow from any vents; face, foot, defrost. A stretch to say it is blowing at even a normal #1 fan speed.
Resistor and blower motor replaced within last year. Took them out for visual inspection yesterday and both appear ok, no visible issues with either. Original was melted and easy to see the trouble. Has worked well since the repair, until now...
Looking for advice on next trouble shooting steps - I assume the resistor and blower motor are still "good". Switches on dash? Vacuum problem with doors in ducting?
Thanks to all in advance!
Chris
Austin, TX
6 Answers
  • HouseCallAuto
    HouseCallAuto 2/10/2014
    You have a totally clogged cabin filter, that is preventing the strong airflow. The 1-4 blower speeds is a bad blower resistor or a burned connector that goes to the blower resistor.
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    HouseCallAuto
    Chris_W 2/11/2014
    HCA: Thanks for the filter tip! Pulled 2 filters, both very dirty and lots of leaves and small twigs came out as well. Ran the fan on #5 before reinstalling the filter cover clamp and lots of air was flowing from the filter compartment, but nothing from the vents. Reinstalled the cover clamp and still nothing... Other ideas I can chase on this one?

    Thanks for your help. Your time and information is very much appreciated!
  • HouseCallAuto
    HouseCallAuto 2/11/2014
    if it does not come out from the vents when the mode is set to vent, do you feel it coming out another place? Floor or defrost? If it is that you hear the blower running at high speed yet little or no airflow from anyplace then you may have a stuck mode door actuator. try removing the actuator and manually moving the mode door. You will need to get some repair info from a manual or online so you know how to access the mode door actuator. Its not bad to do.
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    HouseCallAuto
    Chris_W 2/13/2014
    HCA:
    Resistor changed. I have fan speed control again. Part was under warranty too.

    Mode door actuator has to be my problem. Airflow still very low at all settings. When set to foot level, get air from defrost. I did not pull the mode actuator yet, but the auto parts store states the heat blend and mode actuators use the exact same part. Only one they had was listed as heat blend; I picked it up, but thought I would check with you before changing.

    Do you agree they are the same?

    Many thanks.
  • HouseCallAuto
    HouseCallAuto 2/13/2014
    No they are not the same. The Mode door >. DORMAN Part # 604113
    The Blend door >. DORMAN Part # 604101
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    HouseCallAuto
    Chris_W 2/17/2014
    Changed mode actuator - what a chore! - and have mode control again. Will replace blend actuator as well. If we put on heat, does not go back to cool unless we turn system off.

    Curios... From your experience, is it odd to have the resistor, mode and blend actuators all go bad at same time?

    Lastly, I just got a CEL with P0139. Possible with my recent work I may have triggered a false
    code? Seems awfully coincidental to have multiple issues at same time...

    Your help is greatly appreciated!
  • HouseCallAuto
    HouseCallAuto 2/17/2014
    The fault code P0139 is not a code that is applicable to an '01 Chevy Silverado 5.3 but the code is a valid code on some other make. I suspect you read it wrong. I would understand mode only or blend only going bad. Never saw both. The resistor yes all the time goes bad but when the resistor fails more than once then it is time to replace the blower motor (drawing too much current) or else a burned connector at the resistor or blower motor.
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    HouseCallAuto
    Chris_W 2/26/2014
    I stand corrected. Had the code re-read last weekend and it is P0135 - 02 sensor. They could not tell me which one; I understand there are 4 sensors on 2 banks. Any hints on identifying which one is bad? I have not looked into the details of replacing, but assume it is something a handy DIYer can handle.

    Also, is this something that must be replaced sooner, rather than later? If I don't address sooner, will it lead to other, more serious and costly repairs?

    Thanks as always
    HouseCallAuto
    Chris_W 3/8/2014
    The fan sage continues. With your help, mode door actuator is replaced and working well. 2/3 weeks ago, fan speed only worked on #5; changed resistor and all was well until yesterday. Now fan only works on 1-4, NOT 5. Changed blower motor last night (under warranty), but still no action on #5. Another resistor? Always possible to give up after just 2 weeks, but given all recent work, possible I have other issues causing problem? All connections look very good; nothing burned out or melted.
  • HouseCallAuto
    HouseCallAuto 2/26/2014
    Replace the driver side front O2 sensor. It would be wise to replace BOTH front O2 sensors. These are the two sensors located before the cats. There is one on each side. It is a fault with the heater circuit of the Bank 1 sensor 1 heater circuit and the fix most often is replacing the O2 sensor. Sometimes it is a wiring issue but not that often.
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  • HouseCallAuto
    HouseCallAuto 3/8/2014
    Check the fuse labeled FRT HVAC which is a 30 amp fuse that is only for the # 5 setting. Check the orange wire at the blower resistor with connector unplugged for battery voltage with key on and blower switch on # 5 setting. If no voltage there on 5 then the blower switch is junk. If the fuse is good and there is voltage at the orange wire then the relay that is only for high blower is junk. The speeds 1 through 4 do not go through this relay the same way. Only highest speed uses the function of this relay to flow separate power from the FRT HVAC fuse just to operate speed # 5.
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