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2000 gp a/c defrost cutout below 36 deg.

T

traveltyme

New member
I have a 2000 GP with climate control. The A/C - cuts out disabling the defrost. Can anything be bypassed to keep defroster / ac enabled??????
Thanks to anyone!
 


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The a/c has to cycle while in defrost its to keep the compressor oiled and the system going to prevent compressor failures urging the winter. But it shouldn't kill the defrost if there is a a/c problem I would say you have some sort of a defrost problem.. Does it stop blowing or does it just switch back to vent or something? Or is it your rear defrost that stops?
 
Let me re-phrase, defrost does function, BUT a/c compressor cuts out disabling dehydration. Service manual states a/c cut out @36deg.
 
Right once it gets that cold the a/c will freeze but once ur engine is warm it should cycle like its suppose to.
 
If the AC is working correctly in "AC mode" (compressor coming on and staying on like it should), but not when you have the defrost on, there may be an electrical problem.
 


I am a master gm tech! I guess I don't understand your issue right... Your having a issue that defaults to cutoff when temp is below 36 which is the way the system is designed to do? When I go in to work tomorrow ill read the description and operation and post it on here directly from gm service information
 
I'm sure there is a way ill get back to you tomorrow.. Have to see what module cuts it off and u could just tap into that circuit to go ahead and enable it to run.. But you could be flirting with compressor damage due to cold of temp in the low side and freezing up and causing a restriction
 
Ok when it's above 36 it cycles the a/c compressor and draws outside air in... When its below it only draws outside air into the vehicle as if the a/c is on because its so cold that's the description and operation of defrost in gm service info
 
Yes, that is by design. BUT, 36deg. (seems to me) is still to "warm" to disable compressor. I pull out of the warm garage, head down the road, say 35deg. outside temp., compressor drops out and windows fog up!! I was hoping that there was a "campaign" on this and I could re-flash the ecm-bcm. But it's probably hard wired in the hvac control module~
Thanks!
Ray
 


Seems kinda odd that you are having this problem, my AC compressor took a dump this past year, it doesnt even work at all and my windows never fog up in this minnesota winter. I also park my car outside so the whole body of the car is cold unlike where you pull out of the garage and its warmers than the outside air. That might be a reason it happens.
 
i pull the relay for my a/c every fall. my windows never fog up. unless in wet from rain or snow, but then it clears up rather fast.


maybe your pass side floor is wet causing all the fog. you know the good old leaking wiper cowl.
 
Being 36 is to cold for the a/c to run due to pressures differential in high and low side and a/c is designed to work in 70 ambient temps and up not below. If it were to be below there would have to be different pressures in the system to illuminate freeze up and any damage that may occur with freeze up condition. And the a/c would still be disabled by high pressure sensors in the a/c. If your haveing fogging issues then I would say they need to be cleaned very good clean windows rarely fog up and with little bit of defrost fog gone quick
 
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