Jump to content

Fan In Heating Controls Not Working

RAF

Recommended Posts

RAF Enthusiast

RAF

Posted
Posted

Hey guys, Ive been having an issue with my 2001 Sierra for the last few days. When I try to turn the A/C or heating fan control on nothing blows out. I can hear the A/C compressor turn on and the light marked A/C goes on and the temp from cool to hot works aswell.

Everything seems to be working except the fan does not go on. I can even hear a click when I put it into high but still nothing blows out of the vents. I checked all the fuses and they are all ok. This also happened to me 2 weeks ago for one day and then went back to working like normal

 

Any help would be greatly appreciated

thanks

tesnoboy Enthusiast

tesnoboy

Posted
Posted
Hey guys, Ive been having an issue with my 2001 Sierra for the last few days. When I try to turn the A/C or heating fan control on nothing blows out. I can hear the A/C compressor turn on and the light marked A/C goes on and the temp from cool to hot works aswell.

Everything seems to be working except the fan does not go on. I can even hear a click when I put it into high but still nothing blows out of the vents. I checked all the fuses and they are all ok. This also happened to me 2 weeks ago for one day and then went back to working like normal

 

Any help would be greatly appreciated

thanks

Have you tried it without AC on? How about with it just on vent, you turn the fan speed control through its speed ranges and does it change speeds? If it doesn't, it is probably the resistor module under the dash. They crap out especially when they get hot. You also said it didn't work on high either which is controlled by the fan motor itself. Be sure to double check everything slowly and separately before you waste a lot of money on the wrong thing. Good luck!

RAF Enthusiast

RAF

Posted
  • Author
Posted

Yes, all speeds are not working but everything else is working. It does the same no matter if it's in the A/C or Hot position

RAF Enthusiast

RAF

Posted
  • Author
Posted

I just went for a short drive with the fan on 2 and nothing came out. After about 10 mins I felt the fan blow but it was really week. I tried to put it onto 3 and 4 and it just stopped working again.

 

Any idea?

tesnoboy Enthusiast

tesnoboy

Posted
Posted
I just went for a short drive with the fan on 2 and nothing came out. After about 10 mins I felt the fan blow but it was really week. I tried to put it onto 3 and 4 and it just stopped working again.

 

Any idea?

That sounds like the resistor module under the passenger side dash. Does it work on 5? The fan itself controls that speed.

RAF Enthusiast

RAF

Posted
  • Author
Posted

No, when it doesnt work, it doesnt work on 5 either

Last night after I picked my gf up from work I had the fan on 3 and told her to kick under the passenger side dash. She did and nagically it started working! Later it stopped working I asked her to do it again and it worked again! lol

I'm guessing it's the motor blower resistor loose? I'll go take it apart in a min and have a look

Archived

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

Go to topic listing

  • Latest Articles

  • Posts

    • Atlas
      AC diagnostic on a neo-classic Camaro

      By Atlas · Posted

      tldr; Shade tree mechanic stumped by variable displacement AC compressor.   Not Silverado related, but for my 2000 Camaro SS. I've never really used the AC since acquiring the car a good handful of years ago. I plan to take it on a trip this summer so I wanted to make sure the AC was in good shape. On an 73 degree day in the shop with the car idling I set the AC on "Max", temp set to cold, and fan on hi. The compressor turned on and air turned nice and cold.   I let it run for several minutes but noticed the compressor never cycled off. The engine was up to temperature enough that it began cycling the cooling fans on high. I had a set of manifold gauges hooked up and it was consistently at about 25 psi on the low side and between 200 and 225 psi (warm engine) on the high side. Per temperature charts, the low side is low (should be 30-35) and the high side is a little high (up to 170 per chart). I read the low pressure as potentially being under-charged underscored by a continually running compressor This was also underscored by temp readings of mid-20 degrees at the vents. Not just cold, freezing cold. Switching off the AC but leaving the HVAC fan on high produced a deluge of condensation underneath the vehicle. I was getting ice buildup on the evap core most likely.   The low reading (25psi) concerned me that the compressor wasn't switching off so I swapped out the pressure switch. No change in behavior, still ran constantly.   The AC clutch works fine as it engages/disengages with the HVAC switch on command. The compressor relay is good as I swapped it with two different known good relays just to be sure. Having eliminated that, and the pressure switch, I added refrigerant, thinking the constant run and low "low" pressure were signs of a slight undercharge. Makes sense, the car is 26 years old and it doesn't appear the AC system has ever been touched.   Adding some R134a didn't meaningfully change the low side pressure. And that's when a lightbulb flashed upstairs. While I consider the car "old", it's possibly "new" enough to have a variable displacement compressor. Did some reading and sure enough. Dangit. I don't work on these for this reason.   Adding refrigerant means the compressor will just compensate and won't really change pressures until it's severely overcharged or undercharged. But at least I wasn't getting ice/frost anymore, but instead high 30 degree temps out of the vents. That's more normal, but with variable displacement now I have no idea where my charge level is at. It's probably overcharged now. The high side even with the engine radiating serious heat was never really over about 225.   The static pressure at room temperature is dead on, before and after the charge. Both high/low equalize after some rest.   I'm thinking I'll need to take it to a shop. I want the proper charge level so I'm not working the compressor too hard. The only way to get an accurate charge is to evacuate and then re-charge with the exact amount specified for the system -- at least that's what I'm reading.   Anyone here with modern automotive AC knowledge?  
    • Byrds8
      Ac not keeping up

      By Byrds8 · Posted

      Mine is in the shop for the AC now. While it did get cold after a bit, it would take a while to even start to cool the air at all. Turns out the compressor was bad and cycling. 
    • KARNUT
      Ac not keeping up

      By KARNUT · Posted

      I call B.S. when I first moved to Texas my first house would only cool to 80 with the Texas heat. The AC tech said it was normal at 100 degrees outside. I remodeled the house put in a new AC. I could hang meat. My cars may need recirculating to start. Once moving it switches to regular AC and I could hang meat. Living in Texas no one would put up with only 20 degrees difference. 
    • Silverado4x4
      Ac not keeping up

      By Silverado4x4 · Posted

      AC in home or auto only cool down 15-25 degrees from outside temp, but what will help is to put the ac in recirc mode this will recirc the Inside cabin air rather then trying to cool down the outside hot air, I always have mine in recirc mode.
    • Mrob7
      1965 GMC 1000 series floor shifter

      By Mrob7 · Posted

      Found the fix for this.  Untightan the bolt just below top linkage on the steering column, turn assembly left to reduce space between the two linkage rods at the steering column, tighten bolt.  Made a big improvement.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...