Do the defroster and AC work together?

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In my previous vehicles I had separate controls for temp, AC on/off, and vent selection. In my '99 2500 there's a dial that selects either AC or the defroster. This seems to make it very difficult to turn the AC system on while running the defroster which is commonly known to be the best way to remove condensation (fog)from the inside surface of the windshield. Does the defroster position on the dial activate the AC system? If not, is there a way to do this?

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1999 White SLT QC LB 4X4 AUTO CS TP SB-Stainless Nerf. Will Bomb for Adventure!

 

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When it is in the defrost mode the A/C compressor cycles on and off and the temp. control can be set to how cold you want the discharge air temp. to be. Hope this will help you.
Phil Stuart

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`01 2500,QC,LB,4WD,ISB,5SPD,
355 LSD,Tow Pkg. ,Forest green PC,Mopar alum. side steps,Mopar Mud flaps,Mist gray seat covers,Tekonsha brake controller. Bone stock and plenty of power. THE BIG GREEN MACHINE.
Built in St. Louis
Phil Stuart

I`M GLAD TO BE CUMMIN`

 

[Archive]

Originally posted by Barracuda:
When it is in the defrost mode the A/C compressor cycles on and off and the temp.

FWIW, this seems to be the standard MO for most automotive A/C systems (well, all the ones *I've* seen in the past 20 years... ). In my '98, the A/C is on for both defrost and defrost/floor, as well as Max, A/C and A/C/Floor.

Fest3er

 

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Thanks guys! That question had been lingering in my brain for awhile and I didn't think about posting until I saw posts re AC. I'm relieved! Note: My prior experience was with german and japanese autos and trucks . . . . Sorry to have dumped so much money on foreign soil . . . . Thank God I finally came around . . . Except, now I'm hearing that the trucks assembled in Mexico are better than St. Louis trucks . . . Mine's from St. Louis. Hmmmmm.

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1999 White SLT QC LB 4X4 AUTO CS TP SB-Stainless Nerf. Will Bomb for Adventure!

 

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quote: now I'm hearing that the trucks assembled in Mexico are better than St. Louis trucks . . . Mine's from St. Louis. Hmmmmm.

[/B][/QUOTE]

Mine is also from St. Louis. Haven`t had a lick of trouble from it yet #ad
have only 2,200 miles,so far so good. The fit and finish of the truck is very good. I am happy with mine #ad
.

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`01 2500,QC,LB,4WD,ISB,5SPD,
355 LSD,Tow Pkg. ,Forest green PC,Mopar alum. side steps,Mopar Mud flaps,Mist gray seat covers,Tekonsha brake controller. Bone stock and plenty of power. THE BIG GREEN MACHINE.
Built in St. Louis
Phil Stuart

I`M GLAD TO BE CUMMIN`

[This message has been edited by Barracuda (edited 06-15-2000). ]

 

[Archive]

Originally posted by Tiburon:
. . Except, now I'm hearing that the trucks assembled in Mexico are better than St. Louis trucks . . .

I think that's just wishful thinking on the part of the guys who wound up with burritos in their vents #ad


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95 2500 SLT Laramie 3. 54, automatic,Herculiner bed liner, JVC cd out of factory infinity system, southwest grill gaurd (a favorite amongst the deer population), K&N, AFC adjusted, dual straight exhaust out of "gutless" cat, Geno's dual EGT/boost gauge, TST #6 plate slid all the way forward, AFC housing slid all the way forward, silencer ring removed
"Layin' the 'SMOKEDOWN' on their ROOdy Poo CANDY GASSERS!"

 

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Well, mine are made in Canada by a German company!

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95' 25004X4,Driftwood,Banks,Warn fender flairs and running boards(Play truck)95 3500,driftwood,Banks&phscotty,30,000 GVW apple and tractor hauler(work truck)

 

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I too am glad to see someone else ask questions about the Air Conditioning System. The problem with mine is that on the selector dial, the two A/C modes are on the left--but if I select a couple of the other modes for just vent operation, the A/C comes on! Any advice? Also, in a non-related issue, on the SLT package, isn't it standard equipment for the light around the key ignition supposed to light up?

2001 2500 QuadCab 4X4, Long Box, Auto 4:10, ISB

 

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KDRABIK here is a thread on the halo light.
https://www.turbodieselregister.com/ubb//Forum4/HTML/001463.html

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I maintain a 1ton quad cab daully truck driven like a sports car.
2001 3500 qc 6sp Cummins

 

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In my 2500, if I select the bi-level position (third dial position), the A/C comes on. As near as I can tell, this shouldn't happen. Any ideas?

 

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DixieDawge, The bi-level position is to have the a/c come out of the dash vents and the heater ducts also. My 92 didn't have this and I hated it! Just one more reason I got rid of the ole' undervalved truck.

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John W. - Indiana - Black 99 4x4 QC Sport LB 24V AT 4. 10 Gears Loaded Including Leather and cab lights,285 BFG A/Ts , 16x8 American Racing Baja Wheels,Bed cover, Bushwacker flares, Ventvisors, Rancho RS5000 Steering Stabilizer, 12,000lb Winch mounted where the spare tire used to be, Walker #21468 straight thru muffler... and my Halo light still works!! Bomb My truck?? No way!!(Wink Wink) More to come ...

 

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I guess we just chalk it up to inconsistencies in the dash markings (there's no snowflake in the bi-level position).

So I went to the manual... . this cracked me up so much I had to read it aloud to people around me... In describing the system controls, it actually said there were positions where the AC may or may not be on... What??!! does it have a will of it's own?! IF I'm not controlling it, who is?

By the way, did monkeys write that owner's manual? Grammatically it's only a hair better than my Italian-to-English (literally translated) Ducati manual!

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'01 2500 SLT+, QC, LWB, 4X4, 3. 54s, AT, every option but running lights! To come: 19. 5"s (?), lift, Line-X, Exhaust brake, 4" turbo to tail, etc...

'98 DUCATI ST2 "Bombed" 944CC with Ducati Performance Carbon Fiber Exhaust, F. I. M. Chip, K&N and "modified" air box.

 

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Originally posted by Scooby:
... In describing the system controls, it actually said there were positions where the AC may or may not be on... What??!! does it have a will of it's own?! IF I'm not controlling it, who is?

Actually, technically speaking, you *don't* control the A/C compressor. You only indicate your desires to the PCM; *it* controls the compressor.

As near as I can tell, the A/C will never be on in the vent- and floor-only positions (oh, and OFF). The A/C *can* be on in all other positions. Ignoring that the PCM cycles the compressor to maintain pressures in a certain range, the PCM also will not engage the compressor if the ambient temperature is too low. I *think* my A/C will run down to 22F-25F, if not a bit lower. Also, if there's too much or too little refrigerant in the system, the A/C won't run. If your accessory belt has failed, the A/C won't be on. #ad
If the engine isn't running, the A/C won't be on. #ad
#ad


DC may have been referencing these sorts of conditions when they said the A/C may or may not be on.

Like the blonde replied, when asked to tell his wife if the turn signal of her Ram was on, "Yes. No. Yes. No. Yes. No. " The A/C operates in a vaguely similar fashion.

Fest3er