Jump to content

04 Ac Concerns

miket_99

Recommended Posts

miket_99 New Member

miket_99

Posted
Posted

Have an 04 GMC Z71 with the SLT pkg. The truck has the digital dual climate controler. I am having issues with the A/C working intermittently. If I do not turn the A/C off then the fan off before shutting the truck off, the next time I start back up the A/C will not work. In order to get the A/C back on, I have to turn off the A/C, then the fan, then the truck. This often works, but can take muliple tries in order to get the A/C operating again. I am wondering if the controller might be going out, or if ther is some other switch that might be having an issue.

 

Any suggestions would be appreciated.

 

Thanks,

Mike

bill190 Enthusiast

bill190

Posted
Posted

These things are quite complex with various electronic (computer) modules controlling this and that. Then all sorts of sensors for various things. You would pretty much need a factory wiring diagram manual to test the inputs/outputs and a multimeter. Also to check that each electronic gizmo is getting its full 12 volts as it should (not a poor connection somewhere).

 

Then also you would need to be skilled in advanced electronic troubleshooting. Need to understand how all this works as a system, then be able to monitor/test various inputs outputs. If you can do this, then get a GM factory service manual for your year/model vehicle, and test away!

 

Other than that, your options would be to guess and start replacing things. Maybe start with the main control module. But it could be something else and doing this would be money down the drain. Maybe you could find the same modules at a wrecking yard for not too much?

 

Or take it to a GM dealer.

flhusa1 Enthusiast

flhusa1

Posted
Posted

open the hood and tap on the low pressure switch. if your ac starts working go to napa and buy a new one. unsrew old one screw in new one and you will have ac. mine did exact same thing replaced low pressure cycling switch and it has been fine. there was a gm tech bulletin on this problem.

miket_99 New Member

miket_99

Posted
  • Author
Posted
open the hood and tap on the low pressure switch. if your ac starts working go to napa and buy a new one. unsrew old one screw in new one and you will have ac. mine did exact same thing replaced low pressure cycling switch and it has been fine. there was a gm tech bulletin on this problem.

 

 

Thanks, I will give that a try. But I am like Medic550, Where is the low pressure cycling switch located?

bill190 Enthusiast

bill190

Posted
Posted

I don't know about your specific year (they like to move these things) but on older vehicles it is on the accumulator which is a metal "can" which the A/C lines connect to. It looks like this...

 

accumulator.jpg

flhusa1 Enthusiast

flhusa1

Posted
Posted

thats where it is. left side of firewall has a plug with wires going to it. just tap on the switch with a scewdriver handle. if the ac kicks on buy a new switch.

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.3k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,716
    Total Members
    8,960
    Most Online
    BDS my HD
    Newest Member
    BDS my HD
    Joined

  • Who's Online   5 Members, 0 Anonymous, 602 Guests (See full list)

  • Latest Articles

  • Posts

    • BDS my HD
      Brand new to this forum. Questions about re-gearing my 26’ HD

      By BDS my HD · Posted

      Hello hello looking forward to expanding my knowledge of the 2026 2500 HD that I just bought.   Truck has 3500 miles on it four-wheel-drive crew cab and I’m about to put a 6 1/2 inch BDS lift on it 18 x 10 -25 offset with 37’s   Already have the wheels and tires just waiting on the lift install in about three weeks   Question what surprises am I not gonna be happy with?  I’m not new to lifted trucks so I know that acceleration towing gas mileage all that is affected..   Question is those of you that have this truck this powertrain with a 10 speed Allison and have done the mods that I’m doing,,, how bad is it? Is that Allison constantly gonna be hunting for the right gear to go into? And what about towing, acceleration, fuel consumption as mentioned?    Lastly how come I can’t find any ring pinion gear set up for these axles and when could I expect to see them?   I apologize if there’s any typos I’m doing speech to text on my iPhone.    
    • linc45bn
      2013 2500HD 6.0L intermittent no crank no start

      By linc45bn · Posted

      I've got a 2013 2500 6.0L Flexfuel. Drove the truck earlier today with no issues. Went to run an errand tonight and noticed key fob wouldn't work. Figured battery was dead, so replaced fob batter. Still wasn't working. Grabbed my other set of keys with the other fob and that one wasn't working either. So I manually unlock truck and insert key. Interior lights come on, dashboard lights up, turn key and truck starts. Turn truck off, like a moron, and try starting again. This time no crank, no click, no nothing. Lights still come on and dash lights up, but now I'm getting a service 4wheel drive, service tire monitor, etc. Check voltage on battery and Im showing 12.2v. Throw my battery charger on it and give it 15 mins and try starting again. But still no crank no start. Decide maybe its a bad battery, run to autozone grab a new one and put it in. Same issue. Disconnect battery and let it sit for 15 mins. Try again and still nothing. I had managed to roll the windows down earlier as its a humid night, but now I can't get them to roll up. Power locks are also not working now. Then randomly I try the key again, and it fires right up. Immediately I roll up the windows as we have nothing but rain forecast this week. I shut it back off wait 30 seconds and start up again. Worked a 2nd time. So turn it off, start putting things back together. Try one more time, and back to no crank no start. And now the car alarm starts going off. Had to disconnect battery and leave it that way for the night as I don't think my neighbors would appreciate my alarm going off again tonight. Any thoughts or help would be appreciated. 
    • Grumpy Bear
      first oil change - 2026 2500HD gas

      By Grumpy Bear · Posted

      No one will care for you like you care for you. Do what you can for as long as you can. IMHO of course. 
    • Grumpy Bear
      Oil Consumption

      By Grumpy Bear · Posted

      How about them NICKS!!! 
    • Peoplemvr
      GMC 1500 Illuminated Front Grill Emblem REPLACEMENT.

      By Peoplemvr · Posted

      Hi there.  Long time lurker, first post.    i have read the previous posts regarding the water ingress problem with this emblem.  I bought my 1500 SLT the  summer of 2025 new and after reading the MANY problems with these emblems failing I decided to install one anyways.  As per a YouTube video, I sealed ( or tried to) this sign with silicone sealant around the outer perimeter joint and the holes that were already somewhat sealed on the rear plate of the emblem.  And installed the connector assembly using dielectric grease on the connectors. The installation looked great and worked well for about 4 months……then FAILURE.  Grrrrrr…… I live in the great white north and wash my truck weekly in an automatic car wash  to keep the salt off.  Let me tell you that removing the old, failed emblem is a whole different animal than removing the OEM individual letters without removing the grill assembly. Mainly because the illuminated logo is built differently than the original letters which  you can remove the red surface lettering with a knife or some kind of blade which gives access to the tabs which hold the logo onto the grill. So I had to essentially destroyed the old emblem to remove it. Doing so killed my chance of doing somekind of autopsy on the failed , old logo.  But there was plenty of water inside when I ripped it apart.  Prior to installing the new assembly I tried it with the old harness and it works fine.   Does anyone have any insight as to where the water is getting into this emblem? I intend to seal the new logo with slow curing epoxy this time around using a syringe.  I think this newer emblem may be an updated unit which I hope GM got the vendor to fix. It has an October 2025 date on it.    If this one  fails,  I am just going to revert back to the non-illuminated letters….AFTER PULLING THE GRILL.    Any thoughts on sealing with epoxy would be appreciated. Thx!   Doug  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...