Air condition performance - The 1947 - Present Chevrolet & GMC Truck Message Board Network

asolde · 08-17-2014, 02:53 PM

When running my air conditioner the temp of the air at the outlets goes between 60* and 68*. I have put a vacume on the system and leak check good, serviced it with freon with the engine running until the sight glass was clear reading about 38-40 psi on the guage. I weighed the freon going into the system at around 3.5 lbs. I replaced the compressor switch to begin with, replaced the water heater control valve. Replace the thermostat and fan clutch today engine runs normal 195* Seems like at lower speeds or at idle it runs the coolest,when I get up to speed the tempature goes up to 68* and back down to 60* or so depends. I would like to see 50* at all time at the outlets. Any Ideas of what is wrong?

**truckdude239** · 08-17-2014, 03:50 PM

i'd pull some back out try to get down around maybe 3 pounds witha pressure of 30-35 psi sounds like its over charged

Andy4639 · 08-17-2014, 04:41 PM

Is this R-12 are 134A Freon? If it's 134A it will take less than R-12. Don't go by the sticker for R-12.

To much charge is just as bad as not enough.

I would also put a mechanical shut off in line with the vacuum shut off. If any heated water is coming through to the heater core will make the AC seem hotter.

My 134a runs about 45-50* depending on outside temps. No matter what the motor is running. Make sure the belt on the compressor is tight, very tight!

asolde · 08-17-2014, 08:44 PM

I am running R12. I did a little test called out in the service manual for a over charged condition, but the test turn out normal. I might put that manual shut off in my water heater line just to make sure no hot water is going through the heater core.

**DeadheadNM** · 08-17-2014, 09:00 PM

Alex you can try feeling the supply hose to the heater core to see if the valve is malfunctioning and sending hot fluid to the core.

engineer_gregh · 08-18-2014, 08:21 AM

I would also check the flap in the diverter box on the inside of the truck. That seems to be easily broken. I'm not sure I understand what the compressor switch you referred to is? If you mean you replaced the POA valve with a hi lo pressure switch, was it calibrated for R12 or 134a?

08-17-2014, 02:53 PM	#1
asolde Registered User Join Date: Apr 2012 Location: Henderson Nevada Posts: 804	Air condition performance When running my air conditioner the temp of the air at the outlets goes between 60* and 68. I have put a vacume on the system and leak check good, serviced it with freon with the engine running until the sight glass was clear reading about 38-40 psi on the guage. I weighed the freon going into the system at around 3.5 lbs. I replaced the compressor switch to begin with, replaced the water heater control valve. Replace the thermostat and fan clutch today engine runs normal 195 Seems like at lower speeds or at idle it runs the coolest,when I get up to speed the tempature goes up to 68* and back down to 60* or so depends. I would like to see 50* at all time at the outlets. Any Ideas of what is wrong? __________________ 1972 cheverolet K5 CST Blazer 350/auto/AC/PS/PB/Aux Batt From Medford, Oregon

08-17-2014, 03:50 PM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,232	Re: Air condition performance i'd pull some back out try to get down around maybe 3 pounds witha pressure of 30-35 psi sounds like its over charged __________________ 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

08-17-2014, 04:41 PM	#3
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Air condition performance Is this R-12 are 134A Freon? If it's 134A it will take less than R-12. Don't go by the sticker for R-12. To much charge is just as bad as not enough. I would also put a mechanical shut off in line with the vacuum shut off. If any heated water is coming through to the heater core will make the AC seem hotter. My 134a runs about 45-50* depending on outside temps. No matter what the motor is running. Make sure the belt on the compressor is tight, very tight! __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

08-17-2014, 08:44 PM	#4
asolde Registered User Join Date: Apr 2012 Location: Henderson Nevada Posts: 804	Re: Air condition performance I am running R12. I did a little test called out in the service manual for a over charged condition, but the test turn out normal. I might put that manual shut off in my water heater line just to make sure no hot water is going through the heater core. __________________ 1972 cheverolet K5 CST Blazer 350/auto/AC/PS/PB/Aux Batt From Medford, Oregon

08-17-2014, 09:00 PM	#5
DeadheadNM Carpe manana Join Date: Dec 2010 Location: Eau Claire, WI Posts: 12,355	Re: Air condition performance Alex you can try feeling the supply hose to the heater core to see if the valve is malfunctioning and sending hot fluid to the core. __________________ 1972 K5 CST Highlander Blazer: http://67-72chevytrucks.com/vboard/s...d.php?t=708547 1972 K20 Cheyenne Super: http://67-72chevytrucks.com/vboard/s...d.php?t=528308 Members met: ORANGBLAZ, 2003 silverado, MikeCofield, BB72CHEVKT, Duncan&Son, Sameyrasmea72, THENEWMEXICAN, HotRod C/10, brianthelion02, Sport/Truck, ryanroo, michael bustamante, Dirt's72, Already Gone, WestButteTruck, 57taskforce, Moreyel, painterljp, AASmedic, SoCoC10, Lumaestas, carbuff382, Chevyland

08-18-2014, 08:21 AM	#6
engineer_gregh Registered User Join Date: Feb 2012 Location: Smyrna TN Posts: 1,153	Re: Air condition performance I would also check the flap in the diverter box on the inside of the truck. That seems to be easily broken. I'm not sure I understand what the compressor switch you referred to is? If you mean you replaced the POA valve with a hi lo pressure switch, was it calibrated for R12 or 134a?

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