A/C Problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

m455sx · 07-30-2012, 10:17 AM

I just starting to notice that the A/C is not working correctly. It works well going down the road but when in slow traffic in blows cold at slow speed10-25 mph, then once i hit gas and RPM's raise the warmer it blows. It seems i have a vacuum problem or control going bad? Please advice.
The truck is a 2003 GMC 2500 HD Crew Cab SLT with the 8.1L.

pontgta · 07-30-2012, 02:50 PM

More than likely you are low on freon(leak)

Take a reading when the car is idiling should have about 35-45 psi... If you acelerate while parked i bet your compressor will cylce on and off(should not cycle off below 2000rpm).

**truckdude239** · 07-30-2012, 03:27 PM

at idle pressure should be anywhere from 35-50 on the low and 150-225 on the high side

m455sx · 07-30-2012, 05:15 PM

I thought it maybe a freon leak. I picked up a can from Walley world that had oil, freon in one with gauge. I put in just 3 lbs worth. from 48 lbs to 51lbs, keep in mind it was 95 degrees at Myrtle beach that day. No change at all. Im not sure if problem is new or old as the truck only gets driven 3k-4k miles a year.

pontgta · 07-30-2012, 06:26 PM

Quote:

Originally Posted by m455sx

I thought it maybe a freon leak. I picked up a can from Walley world that had oil, freon in one with gauge. I put in just 3 lbs worth. from 48 lbs to 51lbs, keep in mind it was 95 degrees at Myrtle beach that day. No change at all. Im not sure if problem is new or old as the truck only gets driven 3k-4k miles a year.

3lb worth seems to me like you had 0 to begin with.... what did the label say in the engine bay? 48 to 51 seems high...

at 95 degrees the high should be about 230....low should still be 35-45...maybe even 25-40....

**truckdude239** · 07-30-2012, 09:25 PM

ummmmm theres not way that the truck will take 51 lbs of freon, 3 lbs is still alittle high.

the factory spec for frezon is 1.76lbs system charge if you hvae to much freon in it it wont cool either you need to take it in for a a/c service to have the freon pulled out and proper ammount put back in. thats why i love my reclaim machine at work take all the guess work out just recover and charge back to factory specs

m455sx · 07-31-2012, 01:22 PM

according to direction that 45lbs max at 85 degrees or lower, but 55lbs is OK if 95 degrees or higher. I am talking lbs of pressure???

**truckdude239** · 07-31-2012, 06:10 PM

maybe you mean psi pressure is messured in psi not lbs

07-30-2012, 10:17 AM	#1
m455sx Registered User Join Date: Nov 2011 Location: powhatan virginia Posts: 402	A/C Problems I just starting to notice that the A/C is not working correctly. It works well going down the road but when in slow traffic in blows cold at slow speed10-25 mph, then once i hit gas and RPM's raise the warmer it blows. It seems i have a vacuum problem or control going bad? Please advice. The truck is a 2003 GMC 2500 HD Crew Cab SLT with the 8.1L. __________________ 1970 442 convertible 1970 Cutlass SX 1962 Chevy Stepside 2011 GMC 3500HD Crewcab SLT DRW

07-30-2012, 02:50 PM	#2
pontgta Registered User Join Date: Nov 2009 Location: Haines City FL Posts: 461	Re: A/C Problems More than likely you are low on freon(leak) Take a reading when the car is idiling should have about 35-45 psi... If you acelerate while parked i bet your compressor will cylce on and off(should not cycle off below 2000rpm).

07-30-2012, 03:27 PM	#3
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,237	Re: A/C Problems at idle pressure should be anywhere from 35-50 on the low and 150-225 on the high side __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

07-30-2012, 05:15 PM	#4
m455sx Registered User Join Date: Nov 2011 Location: powhatan virginia Posts: 402	Re: A/C Problems I thought it maybe a freon leak. I picked up a can from Walley world that had oil, freon in one with gauge. I put in just 3 lbs worth. from 48 lbs to 51lbs, keep in mind it was 95 degrees at Myrtle beach that day. No change at all. Im not sure if problem is new or old as the truck only gets driven 3k-4k miles a year. __________________ 1970 442 convertible 1970 Cutlass SX 1962 Chevy Stepside 2011 GMC 3500HD Crewcab SLT DRW

07-30-2012, 09:25 PM	#6
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,237	Re: A/C Problems ummmmm theres not way that the truck will take 51 lbs of freon, 3 lbs is still alittle high. the factory spec for frezon is 1.76lbs system charge if you hvae to much freon in it it wont cool either you need to take it in for a a/c service to have the freon pulled out and proper ammount put back in. thats why i love my reclaim machine at work take all the guess work out just recover and charge back to factory specs __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

07-31-2012, 01:22 PM	#7
m455sx Registered User Join Date: Nov 2011 Location: powhatan virginia Posts: 402	Re: A/C Problems according to direction that 45lbs max at 85 degrees or lower, but 55lbs is OK if 95 degrees or higher. I am talking lbs of pressure??? __________________ 1970 442 convertible 1970 Cutlass SX 1962 Chevy Stepside 2011 GMC 3500HD Crewcab SLT DRW

07-31-2012, 06:10 PM	#8
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,237	Re: A/C Problems maybe you mean psi pressure is messured in psi not lbs __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube



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