Ac isn’t cold at idle

[scott_williams2]

I have a 97 k1500 with a 5.7 vortec. When highway or interstate drivin my ac is fine no complaints cold. But in stop and go traffic or a drive thru I’m sweating my balls off cuz it blows barely cool. What is the cause of this? Is this normal?

 

[Blanco_obs]

I have the same issue [emoji22][emoji22]


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[bugdewde]

Possibly not enough air flow through the ac condenser in front of the radiator. May have a bad fan clutch.

My limited knowledge of the ac system tells me it either works or it doesn't because it's a closed system. So it might be your radiator fan clutch .

 

[TheAutumnWind]

How clean is the condenser? What condition is your radiator shroud and fan? Have you put a set of gauges on? Hi/Low pressures?

 

[TheAutumnWind]

My 94 blows cold @ idle in 100 degree temps, so it is not "normal"

 

[jdla140]

AC not blowing cold at idle usually means there is insufficient airflow over the condenser. Make sure your condenser along with your entire cooling stack is CLEAN, if the air can't get through the rad the fan won't suck it past the condenser. If the condenser looks rough you can buy a comb specifically to repair the fins. Check operation of your fan clutch as well, if the motor is running warm and the AC isn't blowing cold at low speeds, it should be tight and hard to spin the fan with the engine off. If it freewheels, replace it. Another possibility is the compressor is starting to wear out and does not make sufficient pressure at low RPM's, but I'd start with cleaning the cooling stack and making sure the fan clutch is operating properly.

 

[kennythewelder]

These trucks are bad for this. Poor air flow across the condenser core can be an issue. Yes a new fan clutch can help if air flow is the issue, bit even better than that, is to do an electric fan swap. Electric fans move a lot more air, and at idle tons more air. I did mine some time ago. My AC is always cold. At idle, or driving down the HWY at 75 MPH, it makes no difference. Oh, and Im in south Louisiana, so our temps and himity are the same same as yours. Here is my how to write up on what I did to install my fans. Oh and also, you can pull the blower motor, and clean out the HVAC box. This will help some with how much air is blowing out of your vents. There are some videos about this on you tube.
https://www.gmt400.com/threads/electric-fan-swap-on-the-cheap.41756/

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[smdk2500]

I would also check and make sure that your system has the correct amount of refrigerant in it. Ive seen systems that cool fine at above idle but fall on there face at idle due to a low charge.

 

[TheAutumnWind]

These trucks are bad for this. Poor air flow across the condenser core can be an issue. Yes a new fan clutch can help if air flow is the issue, bit even better than that, is to do an electric fan swap. Electric fans move a lot more air, and at idle tons more air. I did mine some time ago. My AC is always cold. At idle, or driving down the HWY at 75 MPH, it makes no difference. Oh, and Im in south Louisiana, so our temps and himity are the same same as yours. Here is my how to write up on what I did to install my fans. Oh and also, you can pull the blower motor, and clean out the HVAC box. This will help some with how much air is blowing out of your vents. There are some videos about this on you tube.
https://www.gmt400.com/threads/electric-fan-swap-on-the-cheap.41756/

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That would help, but likely not fix the OP's particular problem unless the fan or shroud are the issue. The a/c in working condition should function @ idle.

 

[kennythewelder]

That would help, but likely not fix the OP's particular problem unless the fan or shroud are the issue. The a/c in working condition should function @ idle.

Its very hot and humid here. Same for where the OP lives. I used to have the same issue with my system. Yes it would work at idle, just not near as well. I tried a new fan clutch. That did a little, but very little. Then I tried a 12 blade fan with a new clutch, and that did a little better, but again, nothing like doing the electric fan swap. I did this on my truck, so this is first hand experience. It makes a world of difference, when your at idle for any amount of time in these hot, humid climates. There are a ton of videos on you tube with people saying the same thing I am saying. The large amount of air flow the electric fans pull across the condenser core, is so much more than any engine driven fan can pull, that it is a huge difference at idle. Again, I did this on my truck, and that is why I know what it does. My low and high pressures were with in spec, and my AC did the same thing as the OPs AC. As long as you were driving down the road, all was good, but once you stoped at the red light, the AC went from cold to cool. As soon as you stated moving again, the AC was cold again. Once I dis the electric fan swap, all if this went away. My AC is cold all of the time. Again, this is my experience on my own truck. Im Im not saying that the OP doesnt have other issues, maybe they do, and maybe they dont. And yes the system does need to be in good working order, and pressures with in spec, but an electric fan swap will make a big difference in the way the AC works at idle.