Logan Posted August 27, 2005 Report Share Posted August 27, 2005 Hmmm....over the last week or so the drivers side air was getting warm. Passenger side seemed plenty cold. (dual air system) No codes. No funny sounds. Study the service manual. Mix door or actuator going bad? Started taking the dash apart today to check sensors/doors etc. Study service manual more...... Everything looks ok. Freon pressure looks ok. Perfect pressure for outside temp. Study service manual again....... Then find this little obsure message in the service manual.... "Does the discharge air temperature between the right and left center I/P outlets differ by 2-3 degrees?" Well yeah....more like 5-10 degrees different but.....says go to step 7.... "The A/C system is under charged but not enough to show a difference in low or high side pressures." Grrrrrrrrrrrrr........ Sure enough. 1 can 134a fixed the car. 6 hours wasted taking the IP apart. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
Ranger Posted August 27, 2005 Report Share Posted August 27, 2005 I would have never guessed that low freon would/could cause that. Link to comment Share on other sites More sharing options...
JimD Posted August 27, 2005 Report Share Posted August 27, 2005 Good one, Logan. It took some courage to send this tip to the world. Moral of the story could be; RTFM at least 3 times! Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Bob D Posted August 28, 2005 Report Share Posted August 28, 2005 On some of my cars, 1/2 lb low of freon can make a BIG difference, when everything appears to be in spec. Sticking as 1/2 lb in is the first thing I do when things get wierd... '93 STS.. opened, dropped, wide...fast. Link to comment Share on other sites More sharing options...
95SLS Posted August 28, 2005 Report Share Posted August 28, 2005 And here I thought only I had this type luck. If it can fool Logan, it can get anyone. Mike Link to comment Share on other sites More sharing options...
KHE Posted August 29, 2005 Report Share Posted August 29, 2005 Hmmm....over the last week or so the drivers side air was getting warm. Passenger side seemed plenty cold. (dual air system) No codes. No funny sounds. Study the service manual. Mix door or actuator going bad? Started taking the dash apart today to check sensors/doors etc. Study service manual more...... Everything looks ok. Freon pressure looks ok. Perfect pressure for outside temp. Study service manual again....... Then find this little obsure message in the service manual.... "Does the discharge air temperature between the right and left center I/P outlets differ by 2-3 degrees?" Well yeah....more like 5-10 degrees different but.....says go to step 7.... "The A/C system is under charged but not enough to show a difference in low or high side pressures." Grrrrrrrrrrrrr........ Sure enough. 1 can 134a fixed the car. 6 hours wasted taking the IP apart. Glad you got it fixed. Cars today have 1/2 the amount of refrigerant that they used to 20 years ago. When the system is slightly low on refrigerant, the lack of cooling will show up much sooner than it used to. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
bigjayzway Posted August 29, 2005 Report Share Posted August 29, 2005 I think I too would be a little P'd off if I took the dash apart! Big Jay Life is too short to grow up! Link to comment Share on other sites More sharing options...
TDK Posted August 30, 2005 Report Share Posted August 30, 2005 BigJay, You might not realize that Logan has re-built his DHS into a DTS... a few pieces at a time. This includes as I recall, installing a center console with shift controls, wires etc. and then there are the exterior items like bumpers, Although he went through a lot to diagnose the HVAC, its not much compared to what he did for the transformation (which might be ongoing?) I would guess that Logan knows every clip, nut or screw in a Deville interior (both kinds of 'em) and a great deal of the body work Go Logan go Add power to leave problems behind. Most braking is just - poor planning. Link to comment Share on other sites More sharing options...
KevinW Posted August 30, 2005 Report Share Posted August 30, 2005 I would have never guessed that low freon would/could cause that. Think of it this way: If there isn't sufficient refrigerant to 'flood' the evaporator, the portion near the inlet will be significantly colder than the outlet, which is the opposite effect of normal pressure drop across the core. The left and right airflow separation probably occurs near the evaporator. I would imagine it is next to impossible to balance the refrigerant flow path between the left and right portions because the designs are optimised to minimise pressure drop and overall performance. Vent discharge temperature also varies according to distance from the evaporator. ___________________________________________________ Link to comment Share on other sites More sharing options...
WarrenJ Posted August 30, 2005 Report Share Posted August 30, 2005 Logan, Gotta thank you for the report (in between chuckles at your expense). Low freon, it seems, can be a tricky thing. I got my car back from the detailer a few days ago and was generally pleased. EXCEPT (!) that the very next day my DIC reported "REFRIGERANT VERY LOW," and also "A/C COMPRESSOR OFF." Not "Low" mind you, but "Very Low." Man, was I PO'd! I also had some really bad thoughts about the detailer. Today, I stopped at the local auto parts place and purchased a recharging kit. Since I was "Very Low," I bought the 16 ounce kit instead of the 12 ounce kit. Cleared the codes, hooked up the bottle and started up baby. In short order I was makin' ice cubes. Near as I can tell, the "bottle" is still nearly full! I'd guess the extra 12 ounce can I also bought will likely gather dust for awhile until I can find a needy recipient. I'm a bit suprissed that so small (presumably) a loss resulted in a DIC display of "VERY LOW" refrigerant. Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
WarrenJ Posted August 30, 2005 Report Share Posted August 30, 2005 Think of it this way: If there isn't sufficient refrigerant to 'flood' the evaporator, the portion near the inlet will be significantly colder than the outlet, which is the opposite effect of normal pressure drop across the core. The left and right airflow separation probably occurs near the evaporator. I would imagine it is next to impossible to balance the refrigerant flow path between the left and right portions because the designs are optimised to minimise pressure drop and overall performance. Vent discharge temperature also varies according to distance from the evaporator. Kevin, That sounds quite sensible, but one might think a better design would take that into account. On the other hand, isn't it a wonderfully simple indication of low refrigerant? Oh well, ya pays yer money and ya takes yer choice. Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
Logan Posted August 30, 2005 Author Report Share Posted August 30, 2005 Well, that was the direction of my thinking... With the dash have torn apart, I was thinking to myself...."you know, if the freon is low, this system could be cold one side, and warm on the other." But, the freon pressure gauge readings were perfect. Then I found the service manual statement. It will be a huge time saver for the next guy who's system is a little warm on the drivers side Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
95SLS Posted August 30, 2005 Report Share Posted August 30, 2005 Like I said who would have thunk it? And TDK, you forgot to mention Logan has the only wood grain gas tank! Mike C Link to comment Share on other sites More sharing options...
KevinW Posted August 31, 2005 Report Share Posted August 31, 2005 But, the freon pressure gauge readings were perfect. In my experience, high and low side pressures are not an effective indicator of state of charge. The low side is influenced by evaporator load and compressor RPM, and the high side is more dependent on temperature than level of charge, unless the system is grossly overcharged. An accumulator-based system is best assessed by placing a moderately heavy load on the system and comparing the evaporator inlet and outlet temperatures; the outlet (accumulator side) should be slightly colder than the inlet due to the internal pressure drop across the core. ___________________________________________________ Link to comment Share on other sites More sharing options...
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