radride90 Posted June 6 Share Posted June 6 so another issue, relearning about the Reatta, i noticed the day i picked up the car that it didnt seem to go into MAX AC mode. I read that if you lower the temp to 60 degree it should at that point automatically move to MAX setting and the screen icon that shows outside air with the arrow should change to being a lower arrow indicating recirculate air not drawing in outside air. this does not happen. Any one have an idea as to why this does not occur? i do think it needs a bit of a charge, its not super cold and i know my last Reatta once we installed a new compressor with 134a conversion it was nice and cold even on the hottest days here in South Carolina. Any trouble shooting suggestion are appreciated. Phil Link to comment Share on other sites More sharing options...
2seater Posted June 6 Share Posted June 6 Does it do max ac if selected manually? Link to comment Share on other sites More sharing options...
radride90 Posted June 6 Topic Author Share Posted June 6 20 minutes ago, 2seater said: Does it do max ac if selected manually? how do you select the max ac manually on the 1990 model? i was not seeing that on the buttons. Link to comment Share on other sites More sharing options...
rogold Posted June 6 Share Posted June 6 (edited) On the 1989's, I think when you adjust the temp down below 65 degrees, the display states "Max Cool" or "Max AC" Edited June 7 by rogold 1 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted June 7 Share Posted June 7 My '89 does what rogold says. Otherwise, the climate control screen on the CRT does not have a max cool setting. Link to comment Share on other sites More sharing options...
radride90 Posted June 7 Topic Author Share Posted June 7 13 hours ago, rogold said: On the 1989's, I think when you adjust the temp down below 65 degrees, the display states "Max Cool" or "Max AC" right , so when i lower it to 60 , it should do that automatically but does not, so thats what i am wondering, is there a known reason why this would not operate correctly. the max setting would be nice its in the 90's here now. ..... Link to comment Share on other sites More sharing options...
Ronnie Posted June 7 Share Posted June 7 I'm not familiar with how a '90 HVAC operates. How can you tell if it is in Max Cool? Is there and indicator light on the control panel or something that tells you or does it have a digital readout to let you know like earlier models? Link to comment Share on other sites More sharing options...
2seater Posted June 7 Share Posted June 7 21 hours ago, radride90 said: how do you select the max ac manually on the 1990 model? i was not seeing that on the buttons. My bad 😞. I was away from home and must have remembered a different car. I just checked my 90 and if I adjust the temperature down, the next step down from 65* is 60* and I can hear the compressor engage and the fan kicks up to a high speed, but there is no other indicator it is on max cool. The ambient in my garage at the time was only 52* so it didn’t engage based on temperature alone. 1 Link to comment Share on other sites More sharing options...
ship Posted June 7 Share Posted June 7 I just checked my '91. I agree w/ 2seater. There is no notification on the HVAC unit that calls out "Max AC". I put mine on "Auto" (I always keep it on "Auto" anyway) and dropped the temp down to 60*. Compressor kicked in and fan runs on high. If you turn the temp up to 90*, you'll get the same max heat situation. 1 Link to comment Share on other sites More sharing options...
Ronnie Posted June 7 Share Posted June 7 1 hour ago, 2seater said: the next step down from 65* is 60* and I can hear the compressor engage and the fan kicks up to a high speed, but there is no other indicator it is on max cool. I believe on my '88 it did as you say when in Max Cool, but it also went into recirculate mode that made a louder noise than normal mode that pulls in fresh air. Link to comment Share on other sites More sharing options...
2seater Posted June 7 Share Posted June 7 34 minutes ago, Ronnie said: I believe on my '88 it did as you say when in Max Cool, but it also went into recirculate mode that made a louder noise than normal mode that pulls in fresh air. I believe you are right about recirculate but there doesn't seem to be an indicator for that nor a manual control as I have seen on multiple makes. 1 Link to comment Share on other sites More sharing options...
Anthony Posted June 9 Share Posted June 9 From a previous extensive reading of the service manual on this subject, and studying the duct diagrams, I came to the concusion that there is no way to turn off the outside air other than to turn the entire system off. A big thanks to GM engineers who did us another solid Link to comment Share on other sites More sharing options...
Ronnie Posted June 9 Share Posted June 9 1 hour ago, Anthony said: From a previous extensive reading of the service manual on this subject, and studying the duct diagrams, I came to the concusion that there is no way to turn off the outside air other than to turn the entire system off. Go back and read section 1B1, "Air Conditioning", one more time. I think you might have missed something. If you want to check to see if the BCM is putting your AC in MAX AC & Recirc mode, go to Diagnostics and check the number shown in BD24. Then see the chart below. Link to comment Share on other sites More sharing options...
2seater Posted June 9 Share Posted June 9 I remember looking at the outside air door and I do not believe it shuts off the outside air completely. I don't remember the exact details but either the door is smaller than the opening or it is porous, or something like that. I believe GM always wants at least a little positive pressure in the cabin. Maybe someone that has had this area apart can confirm. Link to comment Share on other sites More sharing options...
Ronnie Posted June 9 Share Posted June 9 2 minutes ago, 2seater said: remember looking at the outside air door and I do not believe it shuts off the outside air completely. When I look at the routing of air closely in part of the photo I circled in red above I think you are right. However, it does confirm there is a Recirculation Mode the system should go into on MAX AC. Is the door that controls that the one the is actuated by an arm that is prone to breaking and really hard to replace? Link to comment Share on other sites More sharing options...
Ronnie Posted June 9 Share Posted June 9 11 minutes ago, 2seater said: believe GM always wants at least a little positive pressure in the cabin. Yeah, on some of the GM vehicles I've owned you can't actually turn the blower motor completely off even though the switch shows it's off. It still runs on a slow speed to keep fresh air moving through the vehicle. Link to comment Share on other sites More sharing options...
Anthony Posted June 10 Share Posted June 10 Note that in the circled photo, there are still two arrows coming from outside. 1 Link to comment Share on other sites More sharing options...
Anthony Posted June 10 Share Posted June 10 Whoever designed this assumed the air would always be fresher outside. I guess they never got stuck in traffic behind a city bus, or drove past a hog farm 1 Link to comment Share on other sites More sharing options...
ship Posted June 10 Share Posted June 10 (edited) On 6/9/2024 at 1:32 PM, Ronnie said: Yeah, on some of the GM vehicles I've owned you can't actually turn the blower motor completely off even though the switch shows it's off. It still runs on a slow speed to keep fresh air moving through the vehicle. I believe this feature started back either in the early or mid 70's. A friend of mine bought a new '75 Olds Cutlass and made mention that the HVAC did not totally shut off. Edited June 11 by ship 1 Link to comment Share on other sites More sharing options...
Ron Walker Posted June 11 Share Posted June 11 I'll attach two photos. Mine is an '89. First photo shows temp set at 65 degrees. Second photo shows next coolest temp which goes to Max Cool and says so. No indicator to show recirculate, though the system may be doing so. 1 Link to comment Share on other sites More sharing options...
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