sonjaab Posted April 25, 2019 Report Share Posted April 25, 2019 Anybody know the procedure/trick to engage the a/c compressor to add r-134 to my system? The converted a/c system in my 93 Deville was ice cold when I bought it in Fla. in Dec. Now after the long winter the a/c compressor wont engage because I figure the r-134 has leaked out. I have the connectors and r-134 to add the stuff but need the compressor to turn on to suck it into the system. Whats the trick? Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
rockfangd Posted April 27, 2019 Report Share Posted April 27, 2019 If the system is too low you should pull a vacuum first, That helps it to pull the charge. I am not familiar with the system on your 93 to say if it can be reset, but I think not. You can always bypass the low pressure switch and see if it engages BodybyFisher 1 Quote GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
sonjaab Posted April 27, 2019 Author Report Share Posted April 27, 2019 (edited) Yea now its so low the comp. dont engage. I need to know the procedure/trick to turn on compressor to suck in the 134. 93 deville. EDIT: I note the other a/c post so I will try that using the climate cont. buttons to turn on the compressor to suck it in. I have a leak detector and will put the wrench to all the fitting to see if they are secure and recharge. The PO had the system changed to r-134 a few years back. It was cold when i bought it in Dec. yea prob. has a leak and will test when dye and 134 added. I do have a homemade evacuator to clear the system BTW. Just dont know the trick to start comp. Its buried down low. Funny my 84 Z-28 the comp. is on top and i can jump the comp.to start and I can add 134. (Yea its been converted too and a leaker) Edited April 27, 2019 by sonjaab Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
rockfangd Posted April 27, 2019 Report Share Posted April 27, 2019 If you had a switchable relay that would work as well. I love them. Basically a relay that has a switch in it. Easier than jumping with wires Quote GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
sonjaab Posted June 8, 2019 Author Report Share Posted June 8, 2019 Still having a issue trying to clear the code to engage the a/c compressor to take a charge of r-134. (Yea its been converted) How do you bypass the lo-pressure switch and exactly where is it? Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 8, 2019 Report Share Posted June 8, 2019 What code you may have a bad low pressure switch Jump the low pressure switch plug if it is bad, I did that on my 96. But don't run it like that, change the pressure switch asap, you do not need to depressurize the system to change it. See my post in this thread, its a long post where I jumped the switch. My name here is Scotty Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
sonjaab Posted June 8, 2019 Author Report Share Posted June 8, 2019 no help............. Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 8, 2019 Report Share Posted June 8, 2019 16 hours ago, sonjaab said: no help............. Here are a couple of photos from a 91 FSM of the 4.9 AC system. The low pressure switch appears to be along the firewall on the passenger side. @sonjaab Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 8, 2019 Report Share Posted June 8, 2019 Did you try deleting the low pressure code? Are you evacuating the system down to -25 psi for a couple of hours to rid moisture, my shop does that to check for leaks and then allow the vacuum to draw the freon in. The stupid little can method that does use the compressor to draw in freon won't fix a system that has become depressurized. Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
sonjaab Posted June 9, 2019 Author Report Share Posted June 9, 2019 Yea I used my FSM and followed inst. to delete comp. lockout code. No luck! Tried several times, disconnected battery. Wasnt sure how to jump the low pressure switch. Couldnt tell if the comp. was engaging or not. Cant actually see the comp. engaging because its buried down underneath. The a/c did work when I bought it in Fla. last year. It was converted to 134. I do have a couple of 20s of r-12 Prob gonna send it to the a/c shop. Figured i would at least try to jump at switch to suck in the 134. Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 9, 2019 Report Share Posted June 9, 2019 I would just remove the plug and jump it, it is possible that the switch is bad because of moisture. Let us know how it turns out Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
sonjaab Posted June 9, 2019 Author Report Share Posted June 9, 2019 (edited) Yea the place I took it to said it had some charge in it but not enuff to engage comp. That guy does not do any repairs or diagnosis just fills. I just couldnt figure out where the lo pressure switch was. The FSM is sort of confusing sometimes. So it will jump da switch and see if comp. engages. I have had success using the small cans to recharge tho. Just have to give it another shot...................... Edited June 9, 2019 by sonjaab Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 9, 2019 Report Share Posted June 9, 2019 The small cans are ok go sort of top off but when the system is depressurized it usually needs evacuation Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
sonjaab Posted June 9, 2019 Author Report Share Posted June 9, 2019 SOB! What a dum-dum I am. I didnt know the location of the lo pres. switch till BBF clued me in! FSM is hard to navigate. Anyhoo, I took off the beauty cover to get to the LPS to jump it and it was DISCONNECTED! I figured it got missed when I had the heater core put in or I figured it was dis. because of the r-134 conversion. Anyhoo I hooked it up and the comp. turned on and I have frigid 34 degree air out of the vents! Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 9, 2019 Report Share Posted June 9, 2019 Success! You know its funny one of the diagrams in the FSM I posted above shows the low pressure switch next to the drier the other near the firewall?! 🤪 What no likes or thanks icons? 😉😂I am trying to catch Bruce 😀 sonjaab 1 Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
sonjaab Posted June 9, 2019 Author Report Share Posted June 9, 2019 Hows that? MMmmmmm Cold a/c Yea it was on the firewall under the beauty cover and un-plugged! Now I can put my Z-28 on the road for summer crusin! Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 9, 2019 Report Share Posted June 9, 2019 I am glad you figured it out and also glad it hadn't leaked down to need a charge. Nice Z-28 Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted June 9, 2019 Report Share Posted June 9, 2019 Glad it sorted out ; good job guys. BodybyFisher 1 Quote Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
rockfangd Posted June 9, 2019 Report Share Posted June 9, 2019 Excellent. Thanks for updating. I have seen them in either place. Quote GM FAN FOREVER Nice, clean, luxury= fine automobile Link to comment Share on other sites More sharing options...
sonjaab Posted June 10, 2019 Author Report Share Posted June 10, 2019 (edited) The 84 Z-28 Was a Va. car and had been converted to 134 when new! The a/c did work when I got it. But the comp. locked up so I removed the belt. New Delco comp. $133 bucks on line. I guess with a system flush, evac. and a new charge of r-134 it should work again. This car came with a set of GM t-top sun shields too. First time I ever seen them or found a on line pic and description. Funny there is no water valve in the heater core lines like the older Caddy, olds, etc. Your feet still get hot! I am gonna put a manual valve in the line in the Z-28. Lots of glass in that car even with the shades! The supposed heater "valve" in these 90 Caddys is a strange one too! Still has hot water going to the core. My 84 and 72 Edited June 10, 2019 by sonjaab Quote 93 DeVille-13 Chevy Impala 72 GTO - 77 Triumph Bonneville 84 Z-28 Syracuse NY Link to comment Share on other sites More sharing options...
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