Pullstart 64,531 #1 Posted June 7, 2023 NEVER OVERLOOK THE OBVIOUS! When we bought Mrs. P’s ‘97 Suburban “DeEtte” from Colorado sight unseen, the seller told me the A/C probably needs a recharge, as it doesn’t work. Two years later, I decide to look into it. Mrs. P is on a girls trip with her mom, three aunts and grandma, so I’m sure she’ll need some excitement when she gets home. They can be hard work! I checked the pressure. It seems to have been recharged about umpteen times too many. Prepared with my meter for real troubleshooting,I decided I’d check fuses and relays. What relay? It was missing. I used a spare from the parts truck. Huh. It works! Now she can ride as cool as she looks! 7 8 Share this post Link to post Share on other sites
SylvanLakeWH 27,515 #3 Posted June 7, 2023 Make sure you emphasize your hard work and extensive time/efforts to fix it - get them brownie points... We won't tell... 2 1 3 Share this post Link to post Share on other sites
ri702bill 8,967 #4 Posted June 7, 2023 (edited) 1 hour ago, SylvanLakeWH said: Make sure you emphasize your hard work and extensive time/efforts to fix it - get them brownie points... And remember, Kevin - one good screwup and the slate is wiped clean. From Hero to Zero in a heartbeat--how do I know? BT,DT...... That same relay, used in a different location, runs the e-lectric fuel pump. Perhaps that one expired and they "borrowed" the AC one...... Edited June 7, 2023 by ri702bill 1 1 Share this post Link to post Share on other sites
JCM 10,017 #5 Posted June 7, 2023 You know the good stuff, CHEVROLET IMO one of the best years. 1 1 Share this post Link to post Share on other sites
squonk 42,522 #6 Posted June 7, 2023 Recharged Umpteen times. Music to my ears. I made good money from the umpteen charge crowd. Almost as much as from the body shops who ran a vacuum pump for 20 minutes and called it good. Schooled more than 1 "know it all" mechanic on the importance of letting a vacuum pump run a couple of hours minimum. I had a garage replace the rear line set on my wife's van a couple years ago. AC worked 1 day. The next day no AC and these pressures! Took it back and asked, " How long did you run the vacuum pump?" He says " 20 minutes". I tell him to start the pump in the morning and turn it off at 2:00 and recharge it. Problem solved! 1 Share this post Link to post Share on other sites
Ed Kennell 40,470 #7 Posted June 7, 2023 7 hours ago, Pullstart said: Now she can ride as cool as she looks! Double fudge brownie points fur sure. 1 1 Share this post Link to post Share on other sites
squonk 42,522 #8 Posted June 7, 2023 8 hours ago, Pullstart said: I checked the pressure. It seems to have been recharged about umpteen times too many. Now she can ride as cool as she looks! Checking the non-running static pressure doesn't tell you a heck of a lot unless you have a PT chart and you compare your findings with the ambient temp. Watch my video. That was with 1.5 lbs. of refrigerant in the system. Exactly what was supposed to be in it. Share this post Link to post Share on other sites
Pullstart 64,531 #9 Posted June 8, 2023 3 hours ago, squonk said: Checking the non-running static pressure doesn't tell you a heck of a lot unless you have a PT chart and you compare your findings with the ambient temp. Watch my video. That was with 1.5 lbs. of refrigerant in the system. Exactly what was supposed to be in it. I understand, and am a big fan of a long run time on the vacuum pump as well 1 Share this post Link to post Share on other sites
Handy Don 13,340 #10 Posted June 8, 2023 15 hours ago, Pullstart said: I understand, and am a big fan of a long run time on the vacuum pump as well I didn’t know anything about this until a couple years ago. Wondered why an A/C tech said it was fixed but he wouldn’t be putting the charge back in for a few hours. He replied that in their shop the minimum vacuum time for a car is 4 hours plus 30 minutes to watch the gauge for change. He said a larger home system could be more, depending on the power of the vacuum pump. The things you learn by asking the right person and listening carefully to the answers. 2 Share this post Link to post Share on other sites
squonk 42,522 #11 Posted June 8, 2023 (edited) On big systems at work, ( 100lbs + of refrigerant) we will pressurize a system with nitrogen up to 400 psi for 24 hrs. Then connect 2 vacuum pumps and run them sometimes up to a week until the system gets down to. 500 microns or less. Often stopping a pump and changing its oil mid way thru. Edited June 8, 2023 by squonk Share this post Link to post Share on other sites
