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A/C inop in max setting #4706722
03/25/18 06:56 PM
03/25/18 06:56 PM
Joined: Aug 2004
Posts: 1,464
San Antonio, Texas
sasilverbullet Offline OP
sasilverbullet  Offline OP
Joined: Aug 2004
Posts: 1,464
San Antonio, Texas
2002 Chevy 1500 Express Conversion van. A/C works fine except when you select the highest setting on the blower switch, quits blowing. Does this in either A/C or Max A/C setting.

Anyone have any ideas of what to replace/check?


03 Porsche 911 Liqui Moly Leichtlauf High Tech 5w-40 & Mahle filter
14 Honda Accord 4dr EX-L 4cyl-M1 0W-20 & WIX XP
02 Chevy 5.7L van-GTX HM 10W-40 & WIX filter
Re: A/C inop in max setting [Re: sasilverbullet] #4706727
03/25/18 07:04 PM
03/25/18 07:04 PM
Joined: Sep 2007
Posts: 8,598
Florida
artificialist Offline
artificialist  Offline
Joined: Sep 2007
Posts: 8,598
Florida
Sometimes the highest speed is on a different electrical circuit than the lower speeds. Diagnosing that circuit is key, and you probably should have a service manual. In any case, check all fuses and relays related to the air conditioner and you might be able to solve the problem.

This is also why in some situations, lower fan speeds don't work, but maximum speed does work.


2010 Lancer Ralliart Sportback
Re: A/C inop in max setting [Re: sasilverbullet] #4706730
03/25/18 07:05 PM
03/25/18 07:05 PM
Joined: Dec 2002
Posts: 42,085
New Jersey
JHZR2 Offline
JHZR2  Offline
Joined: Dec 2002
Posts: 42,085
New Jersey
Aren't these blowers often controlled by a set of resistors? Id suspect that the max speed is no resistor, or a minimal one. Regardless, I'd start there.

If it's PWM, then I think all the circuit hardware is used all the time, so then it would have to be a control issue Id think.

Re: A/C inop in max setting [Re: sasilverbullet] #4706749
03/25/18 07:18 PM
03/25/18 07:18 PM
Joined: Oct 2014
Posts: 1,218
NoVA
Jimzz Offline
Jimzz  Offline
Joined: Oct 2014
Posts: 1,218
NoVA
See if there is a blower fan relay. If so its probably bad. The relays have a low and a single full/high speed setting. They are known to go bad on a single side so it either works at full only or the lower settings only.


yup
Re: A/C inop in max setting [Re: sasilverbullet] #4706751
03/25/18 07:22 PM
03/25/18 07:22 PM
Joined: Nov 2008
Posts: 9,033
Phoenix
dishdude Offline
dishdude  Offline
Joined: Nov 2008
Posts: 9,033
Phoenix
Wow, that's weird. Usually the resistor goes bad killing the slower speeds - my guess is the switch. Does it do it in modes other than A/C?


2018 Challenger SRT
Re: A/C inop in max setting [Re: sasilverbullet] #4706761
03/25/18 07:36 PM
03/25/18 07:36 PM
Joined: Oct 2011
Posts: 2,975
Chicago, IL
Brybo86 Offline
Brybo86  Offline
Joined: Oct 2011
Posts: 2,975
Chicago, IL
Odd, sometimes the max is the same temp/blend door setting and fan speed but just forces recirc mode..?


08 Honda Accord EX-L 2.4L M1 EP 0w20 145k
01 Kymco People 50
95 Lexus LS400 M1 AFE 0w30 193k
95 Yamaha Jog
Re: A/C inop in max setting [Re: sasilverbullet] #4706763
03/25/18 07:38 PM
03/25/18 07:38 PM
Joined: Dec 2013
Posts: 2,177
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,177
Fort Worth, Texas
Check the BLOWER fuse in the underhood fuse block.
Unplug the Blower Resistor assembly harness & Check for melted plastic/overheated Terminals.
Blower on high/Key on...Check for 12 VDC on the Orange & Red wires at the blower resistor assembly connector.

*If you find melted Terminals....Replace the Resistor assembly & Connector along with the Blower Motor as it's probably drawing more continuous current than the connection at the resistor can support. Check Ground# G103 for cleanliness/tightness.

*If everything checks out good.....Replace the Resistor assembly, The High Blower Relay is built into the assembly.


Last edited by clinebarger; 03/25/18 07:45 PM.

2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
Re: A/C inop in max setting [Re: Jimzz] #4706817
03/25/18 08:14 PM
03/25/18 08:14 PM
Joined: Jun 2003
Posts: 33,071
ME
eljefino Offline
eljefino  Offline
Joined: Jun 2003
Posts: 33,071
ME
Originally Posted By: Jimzz
See if there is a blower fan relay. If so its probably bad. The relays have a low and a single full/high speed setting. They are known to go bad on a single side so it either works at full only or the lower settings only.



This. A GM thing.

Re: A/C inop in max setting [Re: clinebarger] #4706841
03/25/18 08:33 PM
03/25/18 08:33 PM
Joined: Aug 2004
Posts: 1,464
San Antonio, Texas
sasilverbullet Offline OP
sasilverbullet  Offline OP
Joined: Aug 2004
Posts: 1,464
San Antonio, Texas
Originally Posted By: clinebarger
Check the BLOWER fuse in the underhood fuse block.
Unplug the Blower Resistor assembly harness & Check for melted plastic/overheated Terminals.
Blower on high/Key on...Check for 12 VDC on the Orange & Red wires at the blower resistor assembly connector.

*If you find melted Terminals....Replace the Resistor assembly & Connector along with the Blower Motor as it's probably drawing more continuous current than the connection at the resistor can support. Check Ground# G103 for cleanliness/tightness.

*If everything checks out good.....Replace the Resistor assembly, The High Blower Relay is built into the assembly.



Thanks for the exact instructions!

Would you happen to know a link to a manual?


03 Porsche 911 Liqui Moly Leichtlauf High Tech 5w-40 & Mahle filter
14 Honda Accord 4dr EX-L 4cyl-M1 0W-20 & WIX XP
02 Chevy 5.7L van-GTX HM 10W-40 & WIX filter
Re: A/C inop in max setting [Re: JHZR2] #4706877
03/25/18 08:57 PM
03/25/18 08:57 PM
Joined: Sep 2005
Posts: 5,663
MIchigan
Warstud Offline
Warstud  Offline
Joined: Sep 2005
Posts: 5,663
MIchigan
Originally Posted By: JHZR2
Aren't these blowers often controlled by a set of resistors?


Yep...Sounds like a bad Blower Motor Resistor.

Last edited by Warstud; 03/25/18 09:08 PM.
Re: A/C inop in max setting [Re: sasilverbullet] #4706932
03/25/18 09:34 PM
03/25/18 09:34 PM
Joined: Dec 2013
Posts: 2,177
Fort Worth, Texas
clinebarger Offline
clinebarger  Offline
Joined: Dec 2013
Posts: 2,177
Fort Worth, Texas
Originally Posted By: sasilverbullet

Thanks for the exact instructions!

Would you happen to know a link to a manual?


I used to subcontract to a subcontractor that worked on nothing but EMT vehicles when your van was new, I know the circuits by heart. The FSM's for your van can still be found in print.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
Re: A/C inop in max setting [Re: sasilverbullet] #4707016
03/25/18 10:43 PM
03/25/18 10:43 PM
Joined: Jun 2003
Posts: 17,342
Deplorable in apple valley, ca
Chris142 Online content
Chris142  Online Content
Joined: Jun 2003
Posts: 17,342
Deplorable in apple valley, ca
Common blower resister problem. Replace the plug that plugs into it too.


02 Wrangler durablend 10w40
87 F250 traveler 15w40
04 Tahoe super-s 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: A/C inop in max setting [Re: sasilverbullet] #4707025
03/25/18 10:47 PM
03/25/18 10:47 PM
Joined: Jul 2009
Posts: 432
Seattle
Superflop Offline
Superflop  Offline
Joined: Jul 2009
Posts: 432
Seattle
Under the hood on the Passenger side on top of the heater housing to the left of the blower motor is where the resister screws in(its rectangular). pull the plug to it and to the motor, check for melt. Most likely need a new resistor.

Last edited by Superflop; 03/25/18 10:49 PM.

2002 saab 9-5 2.3t wagon
2014 dodge grand caravan
Re: A/C inop in max setting [Re: sasilverbullet] #4707029
03/25/18 10:49 PM
03/25/18 10:49 PM
Joined: Jul 2014
Posts: 913
Winnipeg MB CA
Number_35 Offline
Number_35  Offline
Joined: Jul 2014
Posts: 913
Winnipeg MB CA
Originally Posted By: sasilverbullet
2002 Chevy 1500 Express Conversion van. A/C works fine except when you select the highest setting on the blower switch, quits blowing. Does this in either A/C or Max A/C setting.

Anyone have any ideas of what to replace/check?

Just AC, or when calling for heat as well?

Re: A/C inop in max setting [Re: sasilverbullet] #4707384
03/26/18 10:42 AM
03/26/18 10:42 AM
Joined: Sep 2007
Posts: 967
TX, USA
JMJNet Offline
JMJNet  Offline
Joined: Sep 2007
Posts: 967
TX, USA
Have you checked with specific chevy forum?
If there is a common issue, they usually have better experience on the solutions from members.

Nothing against this forum but it is a variety of different brand of vehicle owners which is not necessarily just Chevy or GM.

Last edited by JMJNet; 03/26/18 10:43 AM.

  • 2017 Toyota Sienna
  • 1995 GMC Suburban 6.5L Turbo Diesel


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