99 GMC air conditioning
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=159915
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Topic: 99 GMC air conditioning
Posted By: Tracy Martin TN
Subject: 99 GMC air conditioning
Date Posted: 11 Apr 2019 at 7:46pm
My air quit cooling today. Was working fine. A couple days last year in the fall, it iced over on dryer line back to the compressor. What is most like cause? Thanks Tracy
------------- No greater gift than healthy grandkids!
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Replies:
Posted By: jaybmiller
Date Posted: 11 Apr 2019 at 8:02pm
Shameless and his machine !!!
OK, I know dehumidifiers will ice up if it's too humid and my Ferd stopped running aftr several hours of very hot/humid weather when it was on full cold....
------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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Posted By: Dakota Dave
Date Posted: 11 Apr 2019 at 8:18pm
If you turn it off let it warm up and turn it back on does it work again. Could be over serviced.
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Posted By: Dave H
Date Posted: 11 Apr 2019 at 8:37pm
My guess is low refrigerant, but you have to check it. Unless you have had someone stuffing gas in there before the problem, i think over charging is highly unlikely.
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Posted By: Brian Jasper co. Ia
Date Posted: 11 Apr 2019 at 9:38pm
Does the compressor turn on when you select A/C? Generally the first thing I look at is refrigerant pressures first. If static pressures are reasonable I look for reasons for the system to inhibit compressor operation. It depends on whether your 99 is a half ton or 3/4 as to how the compressor is controlled. Half ton the ECM actually controls the compressor. Looking at HVAC data on a scan tool will show why if the system is inhibiting operation.
------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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Posted By: shameless dude
Date Posted: 12 Apr 2019 at 12:55am
usually to much pressure inside with a lack of freon
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Posted By: Tracy Martin TN
Date Posted: 12 Apr 2019 at 8:35am
Going check pressure today..........I can't post from home on here. Something has changed and I can't figure it out. Thanks Tracy
------------- No greater gift than healthy grandkids!
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Posted By: steve(ill)
Date Posted: 12 Apr 2019 at 8:55am
with motor off there should be approx. 100 psi on the low and high side.. Start truck and turn the AC - ON.. the compressor should engage..... the low side drops to about 30- 40 psi and the high side goes up to approx. 200 psi... If the low is LOW and the HI is LOW, then the compressor might cut out, or run, but not cool........ see where the system STOPS working from above.
------------- Like them all, but love the "B"s.
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Posted By: Dave H
Date Posted: 12 Apr 2019 at 11:14am
What Steve said.
Now a shade tree deal is if the compressor engages, goes a few rounds and disengages and repeats that cycle, there is probably not enough refrigerant in there to build up pressure to keep the clutch engaged.
I am assuming that you have a 134A system. if you just need gas don't let someone talk you into mega bucks to convert to 134A if you do have 12. So if you have 12 and need some there is a product on the internet called Freeze 12 that will fit right in there on a 12 system.
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Posted By: Stan IL&TN
Date Posted: 12 Apr 2019 at 12:45pm
With it icing up last year it sounds like you have low refrigerant. Check them pressures would be good first step. If pressure is low enough the compressor will not come on to protect the compressor.
------------- 1957 WD45 dad's first AC
1968 one-seventy
1956 F40 Ferguson
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Posted By: Tracy Martin TN
Date Posted: 12 Apr 2019 at 5:26pm
The pressure checks 100 on both sides. Current to low pressure switch good. Checked voltage to compressor clutch, it is good. Clutch won't engage. Looks like clutch is bad. Really looking forward to fixing it! Couldn't be more in the way to take compressor off if they tried!........................ If anyone can figure why I can't post from home it would be greatly appreciated. Tracy
------------- No greater gift than healthy grandkids!
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Posted By: desertjoe
Date Posted: 12 Apr 2019 at 8:30pm
Hey Tracy,,,this statement don't sound right,,," The pressure http://i.viglink.com/?key=d7d7aa5ced1ebc0821effbccab897fa0&insertId=81c049fbb13be4af&type=H&exp=60%3ACI1C55A%3A13&libId=juesvb3g010009ks000DAcisuqjnj&loc=https%3A%2F%2Fwww.allischalmers.com%2Fforum%2F99-gmc-air-conditioning_topic159915_post1338699.html%231338699&v=1&iid=81c049fbb13be4af&opt=true&out=https%3A%2F%2Frover.ebay.com%2Frover%2F1%2F711-53200-19255-0%2F1%3Ftoolid%3D10029%26campid%3DCAMPAIGNID%26customid%3DCUSTOMID%26catId%3D11450%26type%3D2%26ext%3D223455388398%26item%3D223455388398&ref=https%3A%2F%2Fwww.allischalmers.com%2FFORUM%2Fshops-barns-varmints-and-trucks_forum4.html&title=99%20GMC%20air%20conditioning%20-%20AllisChalmers%20Forum&txt=%3Cspan%3Echecks%20%3C%2Fspan%3E%3Cspan%3E100%3C%2Fspan%3E" rel="nofollow - checks 100 on both sides.""
The only time the pressure on the high side and low side are the same is when engine is shut down and the pressures equalize thru the orifice tube and IF you are standing close to the car when engine is shut off,,,you can actually hear a hissing that is the freon going from the hi side to the low side of the system.. You should check the pressure switch by unplugging it at the accumulator and put a wire "jumper" to both terminals while engine is running. If the clutch comes on,,the pressure switch is bad and easy to replace. If compressor starts cycling,,check your gauges to see what the pressures are. Normal pressures should be in the range from 20-100 and those are dependant on ambient temps and general condition of compressor. If your pressures are in this ballpark,,and still not cooling,,the orifice tube may be plugged,,or compressor is weak, Hope this helps and Good Luck,,,,
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Posted By: Hubert (Ga)engine7
Date Posted: 12 Apr 2019 at 9:08pm
Joe, if the clutch is not engaging the pressures would still be equalized with the engine running. If there is voltage to the clutch I would go with Tracy's diagnosis of a bad clutch.
------------- Just an old country boy saved by the grace of God.
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Posted By: Coke-in-MN
Date Posted: 12 Apr 2019 at 10:53pm
Jumper out the clutch and apply voltage to it , bypassing switches - Can be other things besides bad coil on clutch
------------- Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel.
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Posted By: desertjoe
Date Posted: 13 Apr 2019 at 9:12am
Chit,,Hubert,,you is right and I went back and re-read ole Tracy's last post and he's pretty much ruled it is a bad clutch,,,but,,,here's another one,,,, On the PT Cruiser I'm workin on,,,I went back and forth checkin this and that and finally reached up from underneath and the friggin compressor was locked up,,,!!!! SOOoo,,,Tracy,,check out that possibility. Sorry for the misdiagnosis,,,,,, 
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Posted By: steve(ill)
Date Posted: 13 Apr 2019 at 9:40pm
Tracy, one thing that does happen with a clutch is wear which causes the air gap to increase in size and the magnet can NOT pull it closed.... Some are adjustable to close it up... you might try PUSHING on the side with a screwdriver while running to see if it will close and start to run ............... or like you said, the clutch could be trashed.
------------- Like them all, but love the "B"s.
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Posted By: steve(ill)
Date Posted: 13 Apr 2019 at 9:42pm
watch this on clutch air gap https://www.youtube.com/watch?v=Hqp9IJ2ivl4" rel="nofollow - https://www.youtube.com/watch?v=Hqp9IJ2ivl4
------------- Like them all, but love the "B"s.
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Posted By: Nbeaux
Date Posted: 25 Jun 2020 at 6:21am
Hey hope you figured with your A/C I've had the same issue with my A/C and my friend advised me to go to an http://https://www.socool.sg/" rel="nofollow - air conditioning service.
The service guy told me that the refrigerant level was low due to inccorect installation. After reinstalling my A/C worked like it was new. 
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Posted By: Tracy Martin TN
Date Posted: 25 Jun 2020 at 9:48pm
After it ran some, locked up compressor. Put a new one on with dryer and orifice tube. Sounded like from the gitgo. Lasted about 9 months. Got a replacement, dryer and orifice tube, pulled vaccum again, this one sounded great, really quiet and cool. Thanks Tracy
------------- No greater gift than healthy grandkids!
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Posted By: chaskaduo
Date Posted: 26 Jun 2020 at 9:54am
Yeah don't ya just hate buying new junk still in the box. 
------------- 1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp
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Posted By: Dakota Dave
Date Posted: 26 Jun 2020 at 8:49pm
Your onlylSted 9 months mine lasted 24 months and 7 days. Warrantee was 24 months. Napa did replace the pump even out of warrantee,barley I was on the hook for everything else. Keeping AC in my 93 lumina APV has been expensive.
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