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#1 |
Registered User
Join Date: May 2007
Location: East Haven, CT
Posts: 882
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Compressor cycles with defrost?
With cold weather here in New England, I have been using my defrost and heat. I never noticed this on other cars/trucks but when I have my defrost on, and I think even the heat, the ac compressor cycles on/off. What is up with this?
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#2 |
In the Forgotten far North.
![]() Join Date: Jul 2007
Location: Anchorage, Alaska
Posts: 2,627
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Re: Compressor cycles with defrost?
Vehicles from the early 80's and newer are designed to cycle the A.C. compressor every now and then to keep them from siezing up from non-use. All it's doing is circulating the oil in the compressor to keep everything lubed inside. No worries no biggie.
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1987 R3500 CREW CAB DUALLY (BIG RED)Acquired 06/12/2015 1990 chevy suburban V2500 5.7L My cluster Mods-Nov 2007 overhead console Stereo install Round 2 Aug 2009 Heated/turn signal mirror upgrade |
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#3 |
Registered User
Join Date: May 2003
Location: Lake Oswego, Oregon
Posts: 1,028
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Re: Compressor cycles with defrost?
An air conditioning system is mainly used to cool the air that’s going through your vents and defroster. A useful side effect of air conditioning is that it reduces humidity levels. Less humid air being pumped through your defroster equals faster defogging on your windscreen.
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Ken Morgan For fun: 1964 Volvo 122 For slow: 1984 Chevrolet C-10 For everything else: 1997 BMW M3 |
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#4 | |
Registered User
Join Date: Oct 2005
Location: Branchville SC
Posts: 1,647
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Re: Compressor cycles with defrost?
Quote:
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2004 z71, 96 z71 on 38s, 88 Chevy k5 blazer, 4in lift. 84 swb project, 82 SWB project , 84 chevy 4x4 lwb project, 88 Jimmy beater/highschool ride. 79 c30. 99 tahoe 4x4 project. and a bunch of parts trucks.. |
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#5 |
Registered User
Join Date: Oct 2005
Location: Branchville SC
Posts: 1,647
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Re: Compressor cycles with defrost?
It does that on defrost because the a/c drys out the air.. like fog on the windshield for example..
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2004 z71, 96 z71 on 38s, 88 Chevy k5 blazer, 4in lift. 84 swb project, 82 SWB project , 84 chevy 4x4 lwb project, 88 Jimmy beater/highschool ride. 79 c30. 99 tahoe 4x4 project. and a bunch of parts trucks.. |
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#6 |
Robert Olson Transport
![]() Join Date: Oct 2002
Location: recent transplant to NC USA
Posts: 20,288
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Re: Compressor cycles with defrost?
i was gonna say i havent had a truck that hasnt done it in years
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Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!! |
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#7 |
Senior Member
Join Date: Sep 2004
Location: Georgia
Posts: 614
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Re: Compressor cycles with defrost?
Mine cycles on even when I have the "vent" on.
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![]() 2012 Silverado LT 1500, 5.3, 6 speed auto '86 SWB C-10 Silverado |
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#8 |
Registered User
Join Date: Nov 2007
Location: San Antonio, TX
Posts: 28
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Re: Compressor cycles with defrost?
According to the repair manual for my '75 GMC the compressor will always be on in defrost mode. It will cycle off when the evaporator temp sensor (or outside air) reaches 35 degrees.
My original A/C controls were marked in one section as Economy Mode, since the compressor or will not cycle on in those positions (I think it was the positions for Floor only or Vent only). Bruce |
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#9 |
1962 C-10
Join Date: Apr 2005
Location: Las Vegas, New Mexico
Posts: 4,978
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Re: Compressor cycles with defrost?
Sounds like something's wrong.... ![]()
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Joseph Chavez ![]() "See the USA in a Chevrolet!!" ......................_____ .........________//__{\_____ ,,,,,,,/__(O)___//___/__(O)_/ 1962 C10 Shortbed Fleetside 327/th350 GV overdrive 1974 C10 Longbed Fleetside 350/th350 "The Trash Truck" 1999 Chevy 2500 OBS, Longbed 5.7/4L80E 4x4 2015 GMC Sierra SLE 1500 4x4 |
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