A/C blows ice cold then just cool then ice cold again?

Dozerboy

Well-known member
Jun 23, 2009
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I've never been in an LBZ or LMM that had a fully engaged fan at idle unless it just stopped after pulling a heavy load up a hill or doing some other sort of hard work or there was a cooling system problem. I don't recall my coolant temps going over 185 either unless I'm pulling a fairly heavy trailer.



Same here other then my coolant is higher then that. I just replaced my tstats a few years ago due to low coolant temp though. I think I'm sitting around 200* now.




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JoshH

Daggum farm truck
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Feb 14, 2007
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i have no issue doing it. turn a/c on, run idle up to 2k, sit there for a few minutes and temp gets hot enough to kick the fan on. this is 95+ degree heat too though. everyone brings me their broken shit when its the hottest out side.... go figure
I see. I thought you meant normal driving/idling should see temps higher than 185. I've tried holding mine at 2,000 RPM to see how hot it gets.
Same here other then my coolant is higher then that. I just replaced my tstats a few years ago due to low coolant temp though. I think I'm sitting around 200* now.
Is that going off the gauge or a scan tool? I put new thermostats in mine a few years ago, but the temps are still what they were when I first installed them.
 

Dozerboy

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Jun 23, 2009
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Both. Right after I did them I pick up 10*-15* and it seemed to help my mileage out some.
I did it more for my trips up north. It sucks when you're running down the freeway in the winter and the defrost isn't enough to keep ice off the windshield.

I miss read James last post. I'm not sure if my fan would lock up if reved it to 2k sitting in park. Other than that the only time it's locked up at Idle is when I have "morning sickness".


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Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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you usually dont get a "full lock up" but you get like a 50% load or so. its enough to pull air across the condenser and keep gauge readings accurate.

a non working fan clutch seriously plays havoc on an a/c system. when i swapped to the kodiak clutch, the a/c worked much better in traffic as the fan came on sooner/longer than the stock clutch. in a black truck thats been outside all day in 110+* heat, every little bit helps :roflmao:
 

Burn Down

Hotrodder
Sep 14, 2008
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Boise Idaho
Does GM not have a specified amount/weight of refrigerant? The first thing they told us in A/C (Caterpillar) class was to forget about the gauges for cooling. Gauges are for showing restriction issues or to show if the system was cycling properly or not. Not questioning anyones methods, just curious if they have a weight recommendation or not.
 

whitetrash21

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Apr 29, 2008
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Does GM not have a specified amount/weight of refrigerant? The first thing they told us in A/C (Caterpillar) class was to forget about the gauges for cooling. Gauges are for showing restriction issues or to show if the system was cycling properly or not. Not questioning anyones methods, just curious if they have a weight recommendation or not.

Mine was acting up last year. Sitting in it eating lunch, AC running, ambient temp about 105*. It was blowing cold, then went hot real fast, stayed that way for a minute then went cold again. Kept repeating this every 5 mins or so. Mike used a SnapOn AC machine to pull it down and check for leaks, then recharged it. If I remember correctly, the system in our truck calls for 26 oz of 134....Mine was about 2 oz low. After the recharge, it blows ice cold all the time
 

zakkb787

<that’s not me...
Sep 29, 2014
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Granite Falls NC
I remember mine had a lbs requirement in the manual. I wanna say 1.74? Just replaced everything except my evaporator. Fresh oil and charge and it's so cold it blows frost sometimes :roflmao: gotta turn it down cause it'll freeze you out.

I can honestly say tho that I've never been in a vehicle that at idle the AC gets colder. It always gets warmer for me in all vehicles
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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There is a sticker on the plastic cover by the hood latch that tells you how much weight the system takes.

My truck likes to have 2-3oz less than required. Gauges showed that by high high side pressure and high low side pressure. Pulled some out and it will freeze up the evap on blower speed 1 and 2 quickly when the humid months come. My tracker needs to be spot on or it causes the belt to squeak when the condenser heat soaks or if under filled it will get really warm at idle quickly. I also bypassed the thermistor in it as I could t get it in a good place on the evap that didn't make the compressor kick off too soon and start blowing warm air.

You can go by weight only but I like both cause I'll fine tune the system in. Its like setting up gears, you can go by factory specs and call it good but depending on what you do, you might benefit from setting the pinion abbot deeper into the ring gear or slightly less back lash.
 

Burn Down

Hotrodder
Sep 14, 2008
7,093
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Boise Idaho
Mine was acting up last year. Sitting in it eating lunch, AC running, ambient temp about 105*. It was blowing cold, then went hot real fast, stayed that way for a minute then went cold again. Kept repeating this every 5 mins or so. Mike used a SnapOn AC machine to pull it down and check for leaks, then recharged it. If I remember correctly, the system in our truck calls for 26 oz of 134....Mine was about 2 oz low. After the recharge, it blows ice cold all the time

2 oz is sensitive... The 793F takes 5.5 pounds and the 994 is 6.5 IIRC:rofl:
 

06LBZCrew4x4

New member
Aug 12, 2017
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Florida
It may be low on freon or your compressor is going out. Sounds like low on freon though.


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My other vehicle 2013 Nissan Altima 3.5 V-6 was doing the same thing kinda, it would blow cold as long as you where moving, parked in the shade it still wasn't as cold as it was brand-new, parked in the shade with the hood open and again it still wasn't as cold as it was new. Took it back thinking Freon, Nope Compressor. Good Luck.
 

zakkb787

<that’s not me...
Sep 29, 2014
2,340
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Granite Falls NC
My other vehicle 2013 Nissan Altima 3.5 V-6 was doing the same thing kinda, it would blow cold as long as you where moving, parked in the shade it still wasn't as cold as it was brand-new, parked in the shade with the hood open and again it still wasn't as cold as it was new. Took it back thinking Freon, Nope Compressor. Good Luck.

Same with my truck. Would get warm on long trips. Turn it off for a while and back on it'd be fine. But on my last trip I believe it froze up and fried my compressor.